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Implications of global climate change for the assessment and management of human health risks of chemicals in the natural environment.
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Global climate change (GCC) is likely to alter the degree of human exposure to pollutants and the response of human populations to these exposures, meaning that risks of pollutants could change in the future. The present study, therefore, explores how GCC might affect the different steps in the pathway from a chemical source in the environment through to impacts on human health and evaluates the implications for existing risk-assessment and management practices. In certain parts of the world, GCC is predicted to increase the level of exposure of many environmental pollutants due to direct and indirect effects on the use patterns and transport and fate of chemicals. Changes in human behavior will also affect how humans come into contact with contaminated air, water, and food. Dietary changes, psychosocial stress, and coexposure to stressors such as high temperatures are likely to increase the vulnerability of humans to chemicals. These changes are likely to have significant implications for current practices for chemical assessment. Assumptions used in current exposure-assessment models may no longer apply, and existing monitoring methods may not be robust enough to detect adverse episodic changes in exposures. Organizations responsible for the assessment and management of health risks of chemicals therefore need to be more proactive and consider the implications of GCC for their procedures and processes. Environ. Toxicol. Chem. © 2012 SETAC.
Authors:
John M Balbus; Alistair B A Boxall; Richard A Fenske; Thomas E McKone; Lauren Zeise
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Type:  JOURNAL ARTICLE     Date:  2012-11-12
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Title:  Environmental toxicology and chemistry / SETAC     Volume:  -     ISSN:  1552-8618     ISO Abbreviation:  Environ. Toxicol. Chem.     Publication Date:  2012 Nov 
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Copyright © 2012 SETAC.
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National Institute of Environmental Health Sciences, Bethesda, Maryland, USA. john.balbus@nih.gov.
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Journal ID (nlm-ta): Environ Toxicol Chem
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ISSN: 1552-8618
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Received Day: 23 Month: 12 Year: 2011
Revision Received Day: 08 Month: 5 Year: 2012
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Volume: 32 Issue: 1
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PubMed Id: 23147420
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DOI: 10.1002/etc.2046

IMPLICATIONS OF GLOBAL CLIMATE CHANGE FOR THE ASSESSMENT AND MANAGEMENT OF HUMAN HEALTH RISKS OF CHEMICALS IN THE NATURAL ENVIRONMENT
John M Balbus*
Alistair BA Boxall
Richard A Fenske§
Thomas E McKone
Lauren Zeise#
National Institute of Environmental Health SciencesBethesda, Maryland, USA
Environment Department, University of YorkHeslington, York, UK
§School of Public Health, University of WashingtonSeattle, Washington, USA
Lawrence Berkeley National LaboratoryBerkeley, California, USA
#Office of Environmental Health Hazard Assessment, California Environmental Protection AgencySacramento, California, USA
Correspondence: * To whom correspondence may be addressed (john.balbus@nih.gov).

INTRODUCTION

Global climate change (GCC) is associated with significant changes in long-term weather characteristics and short-term weather extremes in different regions. The world is becoming warmer overall, with increases in temperature being greatest over land and at high northern latitudes, and least over the Southern Ocean and northern North Atlantic. Snow-cover area is contracting and sea and mountain ice shrinking. Precipitation has increased in many regions at higher latitudes, while decreases have been observed in most subtropical land regions. These trends are expected to continue and intensify into the foreseeable future. While flooding rains are expected to become more common at higher latitudes, many areas that are currently semiarid are projected to experience more prolonged periods of drought. Future tropical cyclones are likely to become more intense, while extratropical storm tracks are projected to move toward the poles, changing wind, precipitation, and temperature patterns 1.

Chemical contaminants in the environment affect human health both directly and indirectly. Direct toxic effects range from acute poisonings and triggering of acute events like cardiac arrhythmias and asthma attacks to chronic effects like cancer and immunosuppression 24. Indirect effects include changes in health risks associated with changes in food supply and water sources as a result of chemical contamination or due to the selection of antibiotic resistance traits in bacteria exposed to veterinary and human antibiotics, metals, and other toxic substances 58. Because the persistence and mobility of toxic chemicals in the environment are affected by weather conditions such as temperature, precipitation, and wind, changes in these processes associated with GCC have implications for human exposures. Also, GCC is predicted to affect human diseases, change behavioral patterns that could influence exposures, and create additional physiologic stress through extreme temperatures. These human impacts of GCC, in addition to affecting health directly, may affect the vulnerability of humans to health risks from chemical exposures 9. Together, these changes in exposure and vulnerability to toxic chemicals may significantly alter human health risks.

To protect health, it is important that policy makers and regulatory organizations consider how GCC may influence chemical risks to humans and develop approaches to adequately assess and manage that risk. At the same time, in addition to GCC, there are other important future drivers of chemical risks, such as urbanization, demographic change, and developments in technology. These nonclimate drivers may also have positive or negative effects on exposure; and in some cases, they may have a bigger impact on human exposure than GCC alone. Future projections of potential chemical risks will thus need to integrate climate and nonclimate drivers.

The present study, one of a series arising from a SETAC-sponsored workshop to explore the potential influence of GCC on the foundation and applications of environmental toxicology and chemistry 1015, presents options for addressing GCC in the assessment and management of the risks of chemicals in the natural environment to human health. Because this topic has not been a focus of the environmental toxicology community, there are few data to support a quantitative analysis of how specific chemical risks may be altered by GCC. Therefore, we begin by exploring the mechanisms by which GCC may alter human exposures and vulnerability to toxic chemicals. Using four specific examples of decision contexts for chemical risks, we then evaluate the robustness of current practices for chemical risk-assessment and management practices in the light of potential changes in human exposure and vulnerability caused by GCC. Where appropriate, we provide recommendations on how existing risk-assessment and chemical management practices could be improved to account for changes in exposure and vulnerability.


ANTICIPATED CHANGES IN THE SOURCE–PATHWAY–RECEPTOR RELATIONSHIP

For humans to be affected directly, chemicals must move through a pathway often called the source-to-receptor pathway. After being released from some source and moving through the environment, often being transformed by physical or biological factors in the process, chemicals must come into contact with and enter the body of a human. Once in the body, chemicals are subject to human toxicokinetic processes, ultimately coming in contact with some target tissue or molecular receptor to initiate an adverse outcome (Fig. 1). This chain of events is often complex, involving transformation of chemicals in the environment and their uptake and accumulation in organisms that play a role in exposing humans to those chemicals (e.g., consumption of contaminated fish). Changes in climate and associated changes in weather patterns, as well as non-climate-related drivers, are anticipated to affect various points in the source-to-receptor pathway, modifying how and to what extent humans are exposed to toxic chemicals and how they respond to harmful effects from those exposures 16.

GCC-related alterations in chemical sources

Adaptation to GCC can influence the use and release of chemicals into the environment. For example, the types of pesticides, pharmaceuticals, and veterinary medicines used and the timing and frequency of their use will likely differ from today in response to changing disease and pest pressures resulting from GCC 17. Biocide use, for example, is likely to increase in response to increases in animal and plant pests and diseases that may arise from increasing temperature and humidity 17, 18. Expected decreases in fossil fuel use resulting from greenhouse gas mitigation policies will likely reduce ground-level air pollution by particulate matter and ozone in urban areas 19, while shifts in the production of some types of biofuels may increase levels of air pollution in rural areas; also, their use may increase their combustion product exposures 20. In addition to changing human patterns of chemical use and other behaviors, GCC may affect the rates of formation of natural toxins (such as fungal and algal toxins) in the environment as well as the geographical distribution of these substances 21, 22.

GCC alterations in chemical fate and transport

It is also likely that GCC will combine with other natural and anthropogenic factors to affect the transport and transformation of toxic chemicals in the natural environment 11, 17, 23, 24. Increases in temperature can result in increased volatilization of persistent organic chemicals (e.g., at contamination sources such as buildings and electrical equipment 25), thereby increasing amounts subject to long-range transport 24, 26. Increases in temperature and changes in moisture content are likely to alter the persistence of chemicals 17, 23. Alterations in soil characteristics (organic carbon, dustiness) and hydrology may change how contaminants are transported around a terrestrial ecosystem as well as the dilution potential of contaminants in rivers and streams. Increases in the occurrence of extreme weather events, such as floods and droughts, will likely alter the mobility of contaminants. For example, flood events have been shown to transport dioxins, metals, and hydrocarbons from contaminated areas to noncontaminated areas 27, 28. In agricultural areas, changes in irrigation practices in response to GCC could also move contaminants from water bodies onto land 18. Changes in the degree and duration of ice cover may affect the degradation of contaminants in some regions 29. For legacy contaminants, such as mercury, that have been released to the environment in the past and reside in soil and sediments, GCC may alter the environment in such a way that the substances are remobilized or released more rapidly.

Increased temperatures can increase metabolic rates for many organisms, thereby increasing the potential for bioaccumulation and biomagnification of some contaminants 30. Temperature-related increases in the uptake and bioaccumulation of metals have been reported for several marine organisms, including crustaceans, echinoderms, and mollusks 21. In a recent modeling exercise of the uptake of methylmercury, increases in temperature resulted in increased concentrations of the compound in fish and mammals 31; temperature increases would also be expected to accelerate the conversion of mercury to methylmercury 32. In some instances, uptake may decrease. Studies of organochlorine concentrations in fish between 1994 and 2008 showed a decline in concentrations with increasing temperature, a trend that could be explained by declines in lipid content over time 33. The reason for the change in lipid content and a possible association with climate effects are unclear 33.

Effects of GCC on human exposure to chemicals

Changes in the sources, fate, and transport of chemicals will have both positive and negative implications for contamination of food, drinking water supplies, air, and, hence, human exposure 16. However, very few studies have been performed to quantify the likely changes in exposure concentrations. In a U.K. study, Beulke et al. 34 quantified the effects of changes in the use, fate, and transport of pesticides, resulting either directly or indirectly from GCC, on surface water and groundwater concentrations. The study showed that concentrations of pesticides in surface waters and groundwaters are likely to increase under GCC and that, for some pesticides, peak concentrations could increase by orders of magnitude. The indirect effects of GCC (i.e., effects on amount of pesticide applied and application timing) on surface-water exposure were found to be stronger than the impact of changes in the climate alone on chemical fate and transport. Additional studies of this type are needed for other classes of pollutant and other geographical regions.

Global climate change will affect not only the concentrations of toxic chemicals in water, food, and air, but also how humans interact with these media; this will also have implications for the degree of human exposure. For example, reduction in the availability of drinking water for many populations could change exposure to waterborne contaminants as human populations shift toward other sources of drinking water (e.g., water from water-reuse and reclamation systems) 35. Changes in climate may also impact the amounts of time humans spend indoors and outdoors, influencing exposure to both indoor and outdoor contaminants 36.

As very few robust studies into the effects of GCC on human exposure to chemicals are available, the authors have attempted to develop a qualitative assessment of how GCC is likely to affect the sources and distribution of a variety of pollutants with an assessment of the likely impact on human exposures (Table 1). Table 1 illustrates that the effects of GCC are likely to be very situation-, chemical class-, and source-specific, and will vary across different geographies and at different times of the year.

Impacts of GCC on human vulnerability and risk

The analysis in Table 1 indicates that while climate change could have a positive effect on exposure, in most instances an adverse effect is anticipated in certain regions and it is possible that this will result in adverse health outcomes. Table 2 provides examples of various health effects and risks for some of the chemical exposures likely to be impacted by GCC. It shows GCC affecting the incidence and episodic frequency of acute events, such as cardiovascular and respiratory mortality from high–air pollution episodes. In regions of some developing countries, the increase in the extent and magnitude of episodes of algal and fungal infestations is likely to correspond to increasing mycotoxin exposures, with attendant increasing occurrence of target organ toxicity and cancer, especially in areas where fungal infestations are endemic and populations are vulnerable 18, 24, 37. For a number of the persistent organic pollutants, with the increased exposure expected in some regions comes increased risk of cancer and endocrine, neurological, and reproductive toxicities (38, see Table 2).

In addition to increased exposure to individual contaminants influencing the existing disease burden, nonchemical stressors related to GCC may alter the vulnerability of humans to toxic insults. The extreme temperatures 39, 40 and high ozone levels experienced during heat waves are independently associated with increased cardiovascular mortality, but temperature also appears to interact with ozone, increasing short-term mortality beyond that expected for either stressor acting independently 4144. Temperature has also been observed to modulate the impact of cardiovascular mortality due to particulate matter in ambient air 45, 46.

There has been limited study of the effect of temperature on the toxicity of chemicals in animal models. Temperature has been observed to increase neurotoxicity from methamphetamine exposures in mice 47, and in general, increasing temperature exacerbates chemical toxicity in animal models 48. A number of other nonchemical stressors have been reported to modify chemical toxicity, such as certain pre-existing infectious and noninfectious diseases, nutritional status, and exposure to violence and other psychosocial stressors 4951. Changes in food-chain structure will likely lead to alterations in the diet, with attendant changes in nutritional status and vulnerability 52. Psychosocial effects of GCC include social and community effects of heat such as violence 53, which may also heighten overall vulnerability to chemical exposures.


IMPACTS OF GCC FOR CHEMICAL RISK ASSESSMENT AND MANAGEMENT

A number of chemical management processes are used in different regions of the world to protect human health from chemical exposure, including the setting of standards for chemical contaminant concentrations in food, air, and water and associated monitoring practices; the embargo or removal from the market of products posing unacceptable risks and related assessment methodologies; warning labels; the mitigation of site risks and related planning analyses; and the development of long-term national and international chemical strategies. Because the influence of GCC on chemical risk management may vary among these different situations, we explore in more depth the decision contexts associated with these processes. Chemical management typically takes into account both short-term and long-term risks, information on toxicity of specific substances, and behavioral and other population characteristics that influence exposure and vulnerability. For example, in approving a pesticide, regulatory agencies typically consider the consequences of acute occupational exposure in someone applying the pesticide, the longer-term fate and transport of that pesticide in the environment or food crop, and the extent to which susceptible populations, such as infants and children, are exposed. As another example, decisions for positioning and permitting of facilities for generating or storing hazardous substances typically take into account both exposure pathways related to the long-term release of chemicals and the probability of flooding, storms, or other weather extremes that may lead to sudden large releases and exposure. The relative importance of changes related to GCC for each of these decision contexts will vary based on the specific questions asked and decisions to be made, the time scale under consideration, and the characteristics specific to the geographic location and populations being analyzed.

In the following sections, four broad groups of chemical contaminants (natural toxins, pesticides, air pollutants, and legacy contaminants) are used to illustrate the implications of GCC for different chemical-assessment and/or management mechanisms.

Natural toxins

Natural toxins are produced by algae (e.g., microcystins), bacteria (e.g., botulinum), plants (e.g., glycoalkaloids, anisatin), and fungi (e.g., aflatoxins, ochratoxins, zearalenone) and include some highly toxic chemicals. These compounds have been reported to elicit a range of effects on human health, including death, effects on growth, liver cancers, cirrhosis, gastrointestinal disease, neurotoxicity, and severe dermal toxicity 5457. Production of these compounds can be very sensitive to environmental factors such as temperature and humidity 54. Indirect effects of GCC may also be important; for example, changes in the distribution and activity of insect vectors may increase the exposure and vulnerability of plants to mycotoxins 54, and increases of runoff of nutrients from agricultural systems and changes in dilution may increase the occurrence of algal blooms 17. Therefore, GCC is predicted to increase human exposure to phytotoxins and mycotoxins in some areas 58. As some of these substances are particularly potent in terms of toxicity to humans, these increases in exposure could have a significant negative effect on the health of populations in certain regions.

Human exposure to natural toxins is currently controlled in many countries through monitoring of concentrations of these compounds in crops, shellfish, and drinking water, although in some regions monitoring is nonexistent. Therefore, any effect of GCC on the occurrence and toxicity of natural toxins to humans will be of direct interest to regulatory and public-health agencies responsible for monitoring these compounds and to suppliers of food or drinking water. The potential impacts of GCC on the occurrence of natural toxins and subsequent impacts on food security in different regions will also be of interest to policy makers at the national and international levels. An analysis of the implications of GCC on the monitoring of natural toxins for food-safety purposes (Table 3) suggests that, due to the likely increase in occurrence, existing monitoring mechanisms may not be robust enough to protect human health in the future. Increases in the occurrence of natural toxins may also compromise the security of foodstuffs and drinking water in some regions, resulting in negative effects on health and well being. Fundamental research and programmatic questions include whether existing monitoring schemes are adequate to protect humans against exposure to natural toxins in the future and the likelihood and potential consequences of an increased incidence of natural toxins in food and water supplies.

Pesticides

Pesticides are important tools in much of modern agricultural production and are critical for vector control in many parts of the world (Table 4). It is anticipated that pesticide use will increase in many parts of the world in response to greater pest activity associated with increasing temperatures 17.

Many insecticides are acutely toxic, and their use in agriculture has resulted in poisonings among workers 59, 60. The long-term health effects of pesticide exposures are less certain, but reviews have identified significant health outcomes in agrarian populations 61, 62. Efforts to minimize human exposure to pesticides have generally focused on the following three exposure settings: pesticide residues in food and drinking water; exposures in farmers, farmworkers, and applicators; and community exposures.

The case of pesticide residues in food is used to illustrate the decision context for risk assessment in the face of GCC. Table 4 indicates that many factors other than GCC might influence dietary pesticide exposure, and GCC could be of minor consequence in some instances. Also, GCC could result in reduced exposure and risk under certain conditions. However, in nearly all cases it is expected that GCC will add to the complexity of risk assessments. The significant changes in exposure to pesticide residues via food are likely to result from changes in decisions on the selection of particular pesticides for application.

Setting of pesticide residue–tolerance levels in foods is a key regulatory activity to protect the safety of the food supply. It requires dose–response data and information on the dietary habits of numerous subpopulations 63. We also foresee worker populations becoming more vulnerable to the effects of pesticides due to enhanced skin absorption from exposure to extreme heat, and we expect dietary habits to change based on food cost and availability. These changes will require more frequent updating of risk assessments. Similarly, monitoring for pesticide residues is needed to ensure a safe food supply and will need to be conducted more often as GCC alters pesticide use. New product registrations are based on regulatory risk assessments, and these are revisited periodically after a new chemical is in use. Table 4 shows how the underlying approaches to monitoring pesticides and assessing their risk may require re-evaluation in the context of GCC. The ability to forecast the safety of the food supply will become more uncertain with more rapid changes in pest-management and dietary behaviors.

Air pollutants

Human activities, especially combustion of fossil fuels for energy, release a wide array of toxic substances into the air (Table 5). Natural processes, ranging from wildfires to biological processes of life and decay, also contribute to harmful air pollution. The two air pollutants associated with the greatest burden of death and disease are fine particulate matter (PM2.5), which comes from a variety of anthropogenic and natural sources, and ozone, which is mostly formed in the atmosphere from a chemical reaction between nitrogen oxides, sunlight, and volatile organic compounds. Health effects associated with both air pollutants include the exacerbation of chronic lung disease, asthma, and myocardial infarction. Particulate matter has also been associated with adverse birth outcomes and neurodevelopmental delays. In the United States, it has been estimated that fine particulate air pollution was responsible for over 130,000 deaths and ozone air pollution for over 4,700 deaths in the year 2005 64.

Concentrations of air pollutants in the atmosphere are strongly influenced by weather conditions. Air stagnation and especially air inversions lead to high concentrations of fine particulate matter, while precipitation and high winds tend to lower concentrations. Ozone concentrations are highest on days with high temperatures and high concentrations of ultraviolet radiation from sunlight. In addition to directly affecting concentrations of PM2.5 and ozone, weather and climate conditions indirectly affect concentrations through influences on natural sources of precursors to these pollutants and on human activities that result in emissions (e.g., increased energy consumption for heating and air conditioning). By altering prevailing patterns of temperature, precipitation, winds, and atmospheric penetration of sunlight, GCC is anticipated to lead to both increases and decreases in air pollutant concentrations 65, 66.

Human health risks from criteria air pollutants are managed by regulatory standards for ambient air concentrations and by emissions-control standards for specific sources, permitting requirements, and other measures. Decisions regarding regulatory measures rely on health risk assessments that in turn use observed concentrations and air-quality models to determine population exposures. Only a few countries around the world have established air-quality monitoring networks to provide accurate data on pollutant concentrations; new techniques, such as satellite observations, may play an important role in the future management of human health risks, especially in developing countries 67. Air-quality models include assumptions about weather conditions to determine critical model parameters that control air pollution–concentration estimates. As GCC progresses, these models will need to be revised to reflect changes in temperature and precipitation and the frequency of unusual weather events.

It is possible that GCC will also contribute to changes in population vulnerability to harmful air pollutants. For example, added cardiovascular stress from high summer temperatures may increase sensitivity to the cardiovascular effects of PM2.5 and ozone 44, 67, 68. Conversely, warmer winter temperatures may both reduce cardiovascular stress and lower emissions of combustion products because of reduced heating needs. Because both human and animal studies of air pollution have devoted few resources to the study of interactions between temperature and air pollution exposures, the extent of change in vulnerability related to higher temperatures is uncertain and comprises a research gap.

Many harmful air pollutants are created by the same processes that produce greenhouse gases, so significant measures to reduce greenhouse gas emissions will in many cases lead to reductions in harmful air pollutants as well. Several studies indicate substantial health cobenefits from these air-pollution reductions resulting from greenhouse gas–reduction measures 6971. Estimates of these health benefits need to account for GCC-related influences on the processes that determine air-pollutant concentrations. Some measures to reduce greenhouse gas emissions, such as the development of alternative fuels and fuel additives, may create novel air pollutants or increase concentrations of existing harmful ones 72, 73. These changes in exposure and the consequent health effects must also be anticipated and assessed in making decisions about greenhouse gas reductions and air pollution.

Legacy pollutants

Legacy pollutants are persistent substances that have accumulated in environmental reservoirs such as surface soils, ice, sediments, and forests 7476. Their slow and continuous emissions from these reservoirs pose a long-term risk to human population and ecosystem health 77. Legacy pollutants include dioxins and dioxin-like compounds, PCBs, mercury released into the environment by mining and combustion processes, radioactive compounds from nuclear weapons testing, DDT, lindane, and others 75. The health effects of these pollutants range from cancer, adverse reproductive outcomes, and impaired neurodevelopment to disruption of the endocrine and immune systems. Unlike the other risks highlighted in the present study, the management of legacy pollutants, at least in developed countries, primarily involves tracking reservoir sources and mitigating exposure rather than controlling or reducing emissions from ongoing economic/industrial activities 78. Developing countries, in addition to often lacking effective monitoring and management of legacy pollutant waste sites, may have populations highly exposed by ongoing recycling and waste-processing activities 79.

Because legacy pollutants persist and bioaccumulate in the environment, longer-term environmental processes related to GCC could influence their fate and transport and alter human and ecosystem exposures 80. The transfer of legacy pollutants among environmental media determines their relative abundance in mobile (water or air) compartments versus reservoir compartments (soil and sediments). Legacy pollutants migrate from one region to another through advection in a mobile phase such as air or water 74. If GCC results in stronger winds and/or stronger river, lake, estuary, and ocean currents, regional and global migration patterns will be altered. The persistence of legacy pollutants depends on chemical transformation processes, some of which are climate-dependent. It will be necessary to understand the potential impacts of GCC on processes such as hydrolysis and biotransformation, which play a key role in removing chemicals from environmental media such as soil, water, and sediments (Table 6).


CONCLUSIONS AND RECOMMENDATIONS

Global climate change may affect multiple steps in the process of human exposure and harm to human health from chemical risks, including emissions from sources, transport and transformation in the environment, and human behaviors and vulnerabilities. For many chemical contaminants, a net increase in exposure is likely in certain regions of the world. While GCC will affect the fate and transport of chemicals in multiple and complex ways, in many cases the main climate-related drivers influencing human exposure will be changes in the types of chemicals used by society, alterations in the amounts and patterns of chemical use, and changes in the rates of formation of natural toxins in natural systems. Also, GCC will affect the way in which human populations interact with the natural environment so as to alter the degree of exposure. Alongside changes in exposure, changes in the sensitivity of humans to chemical exposure are expected due to factors such as increases in the levels of heat stress, psychosocial factors, suppression of the immune system, and alterations in nutritional status due to changes in diet and the quality of foodstuffs.

While each individual impact of GCC on chemical exposure and human sensitivity may not be highly significant and may occur in either a positive or a negative direction, the potential cumulative impacts of multiple influences could significantly alter risks to human health. Despite significant uncertainties, the preponderance of the current evidence suggests that many human health risks from chemicals may be increased in the future if a business-as-usual approach is adopted. Changes in risks are likely to be most significant for chemicals where microbes, plants, and lower animals are involved in the source-to-receptor pathway. Increases in risks are likely to be seen for the natural toxins that are produced by microbes, algae, and plants. The risks of chemicals, such as pesticides, whose use is determined by population responses of fungi, weeds, and lower-order animals, or those, like mercury, whose speciation is altered by the activity of micro-organisms, will also be significantly affected. While the absolute magnitude of changes in average air concentrations related to GCC may be relatively small for a given air pollutant, widespread human exposures, increased peak concentrations in certain geographical areas, and significant health consequences make such impacts of GCC very important from a public-health standpoint.

These alterations in risks have implications for national and international decision makers involved in the regulation and authorization of chemical products and the monitoring and management of chemicals in environmental matrices and foodstuffs. The expected changes reveal that some of the scenarios and models currently used in health risk assessment of chemicals will need updates and revision in order to reflect some of the future changes described earlier. Monitoring methodologies may also need to be adapted in order to cope with increased variability in exposure, sensitivity, and risk, both spatially and temporally. Monitoring and sampling should be done at a frequency sufficient to capture variability, which is likely to increase in many places.

It is also important to recognize that human exposure to chemicals in the environment in the future will be affected by other, non-climate-related drivers such as increased urbanization, future technological developments (such as a move toward more environmentally benign pesticides), ongoing strategies to reduce emissions and other environmental releases (e.g., of persistent organic pollutants), and economic changes. In some cases, these drivers may have a bigger impact on human exposure (either increasing or lowering exposures) and risks than GCC alone.

There are, however, major gaps in our current understanding of how chemical risks will change. A concerted effort is therefore needed at an international level to better characterize the potential impacts of GCC and other future drivers on exposure, sensitivity, and risk. We recommend that work should focus on the following areas. First, the development of future models and scenarios of land use and social, technological, and economic change in order to provide a basis for informing how inputs of chemicals to the environment, in different regions of the world, may change in the future. Second, work should focus on the generation of improved data sets and models for determining future human exposure to chemicals in different environmental matrices. This work should consider the importance of emerging exposure pathways, such as increased inhalation of contaminated dust or exposure consequences of flooding, and consider the implications of human behavioral change on the degree of exposure. Furthermore, there should be focus the development of research programs that aim to fill gaps in our understanding of the interactions between climate and weather parameters and human sensitivity to chemical exposures. Focus should also be given to the refinement of regulatory models and procedures in the light of knowledge gained from work on exposure and human sensitivity to toxicants. Existing risk assessments and chemical management programs should also be updated to determine whether the risks of a current-use product could change in the future. Finally, work should give focus to the development of targeted surveillance schemes for the presence and health effects of select chemicals in different environmental compartments for different regions of the world and at smaller geographical scales to address inequities at the community level.

To address these knowledge gaps, input is required from a wide range of disciplines (including climate science, toxicology, exposure science, public health, environmental modeling, social science, economics, and environmental chemistry) and a range of sectors across the globe. It is essential that future research and assessment programs take a holistic approach and do not just focus on GCC-driven changes alone. Research programs should also include elements of technology transfer and capacity building for developing countries struggling to adapt to GCC impacts, many of which will be most vulnerable to the forecast changes in chemical exposure.


This article is the work of an employee or group of employees of the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), the California Office of Environmental Health Hazard Assessment (OEHHA), and the Lawrence Berkeley National Laboratory, which is operated by the U.S. Department of Energy (DOE) under contract DE-AC02-05CH11231; however, the statements, opinions, or conclusions contained here do not necessarily represent the statements, opinions, or conclusions of the NIEHS, NIH, DOE, U.S. government, OEHHA, California Environmental Protection Agency, or the state of California. The authors acknowledge funding for the Society of Environmental Toxicology and Chemistry international workshop, The Influence of Global Climate Change, on the Scientific Foundations and Applications of Environ Toxicol Chem, which was provided by the American Chemistry Council, Conestoga-Rover and Associates, E.I. du Pont de Nemours & Co., Environ Corp, Exponent, NIEHS Superfund Research Program, National Oceanic and Atmospheric Administration, National Council for Air and Stream Improvement, Norwegian Institute for Water Research, Research Council of Norway, Society of Environ Toxicol Chem, Johnson Foundation at Wingspread, Unilever, U.S. Department of Interior Natural Resource Damage Assessment and Restoration Program, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, and U.S. Geological Survey. The authors would like to thank J. Lee of MDB, Inc. for her outstanding assistance with manuscript preparation and submission.


REFERENCES
1. Intergovernmental Panel on Climate ChangeIPCC Fourth Assessment Report: Climate Change 2007Year: 2007Geneva, Switzerland
2. Belpomme D,Irigaray P,Hardell L,Clapp R,Montagnier L,Epstein S,Sasco AJ. The multitude and diversity of environmental carcinogensEnviron ResYear: 200710541442917692309
3. Casals-Casas C,Desvergne B. Endocrine disruptors: From endocrine to metabolic disruptionAnnu Rev PhysiolYear: 20117313516221054169
4. D'Amato G,Liccardi G,D'Amato M,Holgate S. Environmental risk factors and allergic bronchial asthmaClin Exp AllergyYear: 2005351113112416164436
5. Baker-Austin C,Wright MS,Stepanauskas R,McArthur JV. Coselection of antibiotic and metal resistanceTrends MicrobiolYear: 20061417618216537105
6. Davis JA,Hetzel F,Oram JJ,McKee LJ. Polychlorinated biphenyls (PCBs) in San Francisco BayEnviron ResYear: 2007105678617451673
7. Brammer H,Ravenscroft P. Arsenic in groundwater: a threat to sustainable agriculture in South and South-east AsiaEnviron IntYear: 20093564765419110310
8. Gaze WH,Zhang L,Abdouslam NA,Hawkey PM,Calvo-Bado L,Royle J,Brown H,Davis S,Kay P,Boxall ABA,Wellington EMH. Impacts of anthropogenic activity on the ecology of class 1 integrons and integron-associated genes in the environmentInt Soc Microb Ecol JYear: 20111212531261
9. Arctic Monitoring and Assessment Programme/United Nations Environment ProgrammeClimate change and POPs: Predicting the impactsYear: 2011Geneva, Switzerland Report of the UNEP/AMAP Expert Group Secretariat of the Stockholm Convention.
10. Stahl RG,Hooper MJ,Balbus JM,Clements WH,Fritz A,Gouin TA,Helm R,Hickey C,Landis WGD,Moe SJ. The influence of global climate change on the scientific foundations and applications of environmental toxicology and chemistry: Introduction to a SETAC international workshopEnviron Toxicol ChemYear: 2012321319 (this issue). 23097130
11. Gouin T,Armitage J,Cousins I,Muir DC,Ng CA,Tao S. Influence of global climate change on chemical fate and bioaccumulation: The role of multimedia modelsEnviron Toxicol ChemYear: 2012322031 (this issue). 23136071
12. Hooper MJ,Ankley G,Cristol D,Maryoung L,Noyes P,Pinkerton K. Interactions between chemical and climate stressors: A role for mechanistic toxicology in assessing climate change risksEnviron Toxicol ChemYear: 2012323248 (this issue). 23136056
13. Moe SJ,de Schamphelaere K,Clements WH,Sorensen M,van den Brink P,Liess M. Combined and interactive effects of global climate change and toxicants on populations and communitiesEnviron Toxicol ChemYear: 2012324961 (this issue). 23147390
14. Landis WG,Durda J,Brooks ML,Chapman PM,Menzie CA,Stahl RG Jr,Stauber JL. Ecological risk assessment in the context of global climate changeEnviron Toxicol ChemYear: 2012327992 (this issue). 23161373
15. Rohr J,Johnson P,Hickey CW,Helm RC,Fritz A,Brasfield S. Implications of global climate change for natural resource damage assessment, restoration, and rehabilitationEnviron Toxicol ChemYear: 20123293101 (this issue). 23097077
16. Noyes PD,McElwee MK,Miller HD,Clark BW,Van Tiem LA,Walcott KC,Erwin KN,Levin ED. The toxicology of climate change: Environmental contaminants in a warming worldEnviron IntYear: 20093597198619375165
17. Boxall ABA,Hardy A,Beulke S,Boucard T,Burgin L,Falloon PD,Haygarth PM,Hutchinson T,Kovats RS,Leonardi G,Levy LS,Nichols G,Parsons SA,Potts L,Stone D,Topp E,Turley DB,Walsh K,Wellington EMH,Williams RJ. Impacts of climate change on indirect human exposure to pathogens and chemicals from agricultureEnviron Health PerspectYear: 200911750851419440487
18. Tirado MC,Clarke R,Jaykus LA,McQuatters-Gollop A,Frank JM. Climate change and food safety: A reviewFood Res IntYear: 20104317451765
19. Bell ML,Davis DL,Cifuentes LA,Krupnick AJ,Morgenstern RD,Thurston GD. Ancillary human health benefits of improved air quality resulting from climate change mitigationEnviron HealthYear: 200874118671873
20. Hill J,Polaskya S,Nelson E,Tilmanb D,Huod H,Ludwige L,Neumanne J,Zhenga H,Bontaa D. Climate change and health costs of air emissions from biofuels and gasolineProc Natl Acad Sci USAYear: 20091062077208219188587
21. Marques A,Nunes ML,Moore SK,Strom MS. Climate change and seafood safety: Human health implicationsFood Res IntYear: 20104317661779
22. Cotty PJ,Jaime-Garcia R. Influences of climate on aflatoxin producing fungi and aflatoxin contaminationInt J Food MicrobiolYear: 200711910911517881074
23. Bloomfield JP,Williams RJ,Gooddy DC,Cape JN,Guha P. Impacts of climate change on the fate and behaviour of pesticides in surface and groundwater—A UK perspectiveSci Total EnvironYear: 200636916317716914182
24. Armitage JM,Quinn CL,Wania F. Global climate change and contaminants—An overview of opportunities and priorities for modelling the potential implications for long-term human exposure to organic compounds in the ArcticJ Environ MonitYear: 2011131532154621509380
25. Bogdal C,Scheringer M. Release of POPs to the environment. UNEP/AMAP Expert Group Report—Climate Change and POPs: Predicting the ImpactsYear: 2011Geneva, SwitzerlandUnited Nations Environment Programme/Arctic Monitoring and Assessment Programme
26. Lamon L,VonWaldow H,Macleod M,Scheringer M,Marcomini A,Hungerbuhler K. Modeling the global levels and distribution of polychlorinated biphenyls in air under a climate change scenarioEnviron Sci TechnolYear: 2009435818582419731682
27. Lake IR,Foxall CD,Lovett AA,Fernandes A,Dowding A,White S,Rose M. Effects of river flooding on PCDD/F and PCB levels in cows' milk, soil, and grassEnviron Sci TechnolYear: 2005399033903816382922
28. Manuel M. In Katrina's wakeEnviron Health PerspectYear: 2006114A32A3916393645
29. Point D,Sonke JE,Day RD,Roseneau DG,Hobson KA,Vander Poll SS,Moors AJ,Pugh RS,Donard OFX,Becker PR. Methylmercury photodegradation influenced by sea-ice cover in Arctic marine ecosystemsNat GeosciYear: 20114188194
30. Moore MV,Pace ML,Mather JR,Murdoch PS,Howarth RW,Folt CL,Chen CY,Hemond HF,Flebbe PA,Driscoll CT. Potential effects of climate change on freshwater ecosystems of the New England/mid-Atlantic regionHydrol ProcessYear: 199711925947
31. Booth S,Zeller D. Mercury, food webs, and marine mammals: Implications of diet and climate change for human healthEnviron Health PerspectYear: 200511352152615866757
32. Downs SG,MacLeod CL,Lester JN. Mercury in precipitation and its relation to bioaccumulation in fish: A literature reviewWater Air Soil PollutYear: 1998108149187
33. Riget F,Vorkamp K,Muir D. Temporal trends of contaminants in Arctic (char Salvelinus alpinus) from a small lake, southwest Greenland during a warming climateJ Environ MonitYear: 2010122252225820941435
34. Beulke S,Boxall A,Brown C,Thomas M. Year: 2007 Assessing and managing the impacts of climate change on the environmental risks of agricultural pathogens and contaminants: Pathways for transport of contaminants in agricultural systems and potential effects of climate change. Final report to Defra for project SD0441. Fera, Sand Hutton, York, UK.
35. Bower H. Integrated water management for the 21st century: Problems and solutionsJ Irrig Drain EngYear: 2002128193202
36. Cecchi L,D'Amato G,Ayres JG,Galan C,Forastiere F,Forsberg B,Gerritsen J,Nunes C,Behrendt H,Akdis C,Dahl R,Annesi-Maesano I. Projections of the effects of climate change on allergic asthma: The contribution of aerobiologyAllergyYear: 2010651073108120560904
37. Magan N,Medina A,Aldred D. Possible climate-change effects on mycotoxin contamination of food crops pre- and postharvestPlant PatholYear: 201160150163
38. Food and Agriculture Organization of the United NationsClimate change: Implications for food safetyYear: 2008Rome, ItalyFAO Food Quality and Standards Service, Nutrition and Consumer Protection Division
39. Curriero FC,Heiner KS,Samet JM,Zeger SL,Strug L,Patz JA. Temperature and mortality in 11 cities of the eastern United StatesAm J EpidemiolYear: 2002155808711772788
40. Keatinge WR,Donaldson GC,Cordioli E,Martinelli M,Kunst AE,Mackenbach JP,Nayha S,Vuori I. Heat related mortality in warm and cold regions of Europe: Observational studyBMJYear: 200032167067310987770
41. Dear K,Ranmuthugala G,Kjellstrom T,Skinner C,Hanigan I. Effects of temperature and ozone on daily mortality during the August 2003 heat wave in FranceInt Arch Occup Environ HealthYear: 200560205212
42. Filleul L,Cassadou S,Medina S,Fabres P,Lefranc A,Eilstein D,Le Tertre A,Pascal L,Chardon B,Blanchard M,Declercq C,Jusot JF,Prouvost H,Ledrans M. The relation between temperature, ozone, and mortality in nine French cities during the heat wave of 2003Environ Health PerspectYear: 20061141344134716966086
43. Ren C,Williams GM,Morawska L,Mengersen K,Tong S. Ozone modifies associations between temperature and cardiovascular mortality: Analysis of the NMMAPS dataJ Occup Environ MedYear: 200865255260
44. Ren C,Williams GM,Mengersen K,Morawska L,Tong S. Does temperature modify short-term effects of ozone on total mortality in 60 large eastern US communities? An assessment using the NMMAPS dataEnviron IntYear: 20083445145817997483
45. Staffogia M,Schwartz J,Forastiere F,Perucci CA. SISTI GroupDoes temperature modify the association between air pollution and mortality? A multicity case-crossover analysis in ItalyAm J EpidemiolYear: 20081671476148518408228
46. Ren C,Tong S. Temperature modifies the health effects of particulate matter in Brisbane, AustraliaInt J BiometeorolYear: 200651879616967305
47. Miller DB,O'Callaghan JP. Elevated environmental temperature and methamphetamine neurotoxicityEnviron ResYear: 200392485312706754
48. Gordon CJ. Role of environmental stress in the physiological response to chemical toxicantsEnviron ResYear: 2003921712706749
49. Krewski D,Burnett RT,Goldberg M,Hoover K,Siemiatycki J,Abrahamowicz M,White WH. Reanalysis of the Harvard Six Cities Study, Part II: Sensitivity analysisInhal ToxicolYear: 20051734335316020033
50. Clougherty JE,Levy JI,Kubzansky LD,Ryan PB,Suglia SF,Canner MJ,Wright RJ. Synergistic effects of traffic related air pollution and exposure to violence on urban asthma etiologyEnviron Health PerspectYear: 20071151140114617687439
51. Shankardass K,McConnell RS,Milam J,Berhane K,Tatalovich Z,Wilson JP,Jerrett M. The association between contextual socioeconomic factors and prevalent asthma in a cohort of southern California school childrenSoc Sci MedYear: 2007651792180617658674
52. Lake IR,Hooper L,Abdelhamid A,Bentham G,Boxall ABA,Draper A,Fairweather-Tait S,Hulme M,Hunter PR,Nichols G,Waldron KW. Climate change and food security: Health impacts in developed countriesEnviron Health PerspectYear: 20121201520152623124134
53. Doherty TJ,Clayton S. The psychological impacts of global climate changeAm PsycholYear: 20116626527621553952
54. Paterson RR,Lima N. Toxicology of mycotoxinsEXSYear: 2010100316320358681
55. van Egmond HP. Natural toxins: Risks, regulations, and the analytical situation in EuropeAnal Bioanal ChemYear: 20043781152116014673562
56. Fawell J,Nieuwenhuijsen MJ. Contaminants in drinking waterBr Med BullYear: 20036819920814757718
57. Hawkes C,Ruel M. The links between agriculture and health: An intersectoral opportunity to improve the health and livelihoods of the poorBull WHOYear: 20068498499017242835
58. Miraglia M,Marvin HJ,Kleter GA,Battilani P,Brera C,Coni E,Cubadda F,Croci L,De Santis B,Dekkers S,Filippi L,Hutjes RW,Noordam MY,Pisante M,Piva G,Prandini A,Toti L,van den Born GJ,Vespermann A. Climate change and food safety: An emerging issue with special focus on EuropeFood Chem ToxicolYear: 2009471009102119353812
59. Litchfield MH. Estimates of acute pesticide poisoning in agricultural workers in less developed countriesToxicol RevYear: 20052427127816499408
60. Calvert GM,Karnik J,Mehler L,Beckman J,Morrissey B,Sievert J,Barrett R,Lackovic M,Mabee L,Schwartz A,Mitchell Y,Moraga-McHaley S. Acute pesticide poisoning among agricultural workers in the United States, 1998-2005Am J Indust MedYear: 200851883898
61. Kesavachandran CN,Fareed M,Pathak MK,Bihari V,Mathur N,Srivastava AK. Adverse health effects of pesticides in agrarian populations of developing countriesRev Environ Contam ToxicolYear: 2009200335219680610
62. Koutros S,Alavanja MC,Lubin JH,Sandler DP,Hoppin JA,Lynch CF,Knott C,Blair A,Freeman LE. An update of cancer incidence in the Agricultural Health StudyJ Occup Environ MedYear: 2010521098110521063187
63. International Programme on Chemical Safety (IPCS)Principles and methods for the risk assessment of chemicals in foodYear: 2009Geneva, SwitzerlandJoint publication of the Food and Agriculture Organization and the World Health Organization Environmental Health Criteria 240.
64. Fann N,Lamson AD,Anenberg SC,Wesson K,Risley D,Hubbell BJ. Estimating the national public health burden associated with exposure to ambient PM(2.5) and ozoneRisk AnalysisYear: 201232819521627672
65. Ebi KL,McGregor G. Climate change, tropospheric ozone and particulate matter, and health impactsEnviron Health PerspectYear: 20081161449145519057695
66. Tang X,Wilson SR,Solomon KR,Shao M,Madronich S. Changes in air quality and tropospheric composition due to depletion of stratospheric ozone and interactions with climatePhotochem Photobiol SciYear: 20111028029121253665
67. van Donkelaar A,Martin RV,Brauer M,Kahn R,Levy R,Verduzco C,Villeneuve PJ. Global estimates of ambient fine particulate matter concentrations from satellite-based aerosol optical depth: Development and applicationEnviron Health PerspectYear: 201011884785520519161
68. Qian Z,He Q,Lin HM,Kong L,Zhou D,Liang S,Zhu Z,Liao D,Liu W,Bentley CM,Dan J,Wang B,Yang N,Xu S,Gong J,Wei H,Sun H,Qin Z. HEI Health Review Committee. Part 2. Association of daily mortality with ambient air pollution, and effect modification by extremely high temperature in Wuhan, ChinaResearch Report/Health Effects InstituteYear: 201015491217
69. Anenberg SC,Schwartz J,Shindell D,Amann M,Faluvegi G,Klimont Z,Janssens-Maenhout G,Pozzoli L,Van Dingenen R,Vignati E,Emberson L,Muller NZ,West JJ,Williams M,Demkine V,Hicks WK,Kuylenstierna J,Raes F,Ramanathan V. Global air quality and health co-benefits of mitigating near-term climate change through methane and black carbon emission controlsEnviron Health PerspectYear: 201212083183922418651
70. Markandya A,Armstrong BG,Hales S,Chiabai A,Criqui P,Mima S,Tonne C,Wilkinson P. Public health benefits of strategies to reduce greenhouse-gas emissions: Low-carbon electricity generationLancetYear: 20093742006201519942282
71. Wilkinson P,Smith KR,Davies M,Adair H,Armstrong BG,Barrett M,Bruce N,Haines A,Hamilton I,Oreszczyn T,Ridley I,Tonne C,Chalabi Z. Public health benefits of strategies to reduce greenhouse-gas emissions: Household energyLancetYear: 20093741917192919942273
72. McCormick R. The impact of biodiesel on pollutant emissions and public healthInhalation ToxicolYear: 20081910331039
73. Tsao C-C,Campbell JE,Mena-Carrasco M,Spak SN,Chen Y. Increased estimates of air-pollution emissions from Brazilian sugar-cane ethanolNat Clim ChangeYear: 201225337
74. Scheringer M. Characterization of the environmental distribution behavior of organic chemicals by means of persistence and spatial rangeEnviron Sci TechnolYear: 19973128912897
75. McKone TE,MacLeod M. Tracking multiple pathways of human exposure to persistent multimedia pollutants: Regional, continental, and global scale modelsAnnu Rev Environ ResourYear: 200428463492
76. Conner MS,Davis JA,Leatherbarrow J,Greenfield BK,Gunther A,Hardin D,Mumley T,Oram JJ,Werne C. The slow recovery of San Francisco Bay from the legacy of organochlorine pesticidesEnviron ResYear: 20071058710016930588
77. Cowan-Ellsberry C,McLachlan M,Arnot J,MacLeod M,McKone TE,Wania F. Modeling exposure to persistent chemicals in hazard and risk assessmentIntegr Environ Assess ManagYear: 2009566267919552503
78. Gouin T,Wania F. Time trends of Arctic contamination in relation to emission history and chemical persistence and partitioning propertiesEnviron Sci TechnolYear: 2007415986599217937271
79. Linderholm L,Jakobsson K,Lundh T,Zamir R,Shoeb M,Nahar N,Bergman Å. Environmental exposure to POPs and heavy metals in urban children from Dhaka, BangladeshJ Environ MonitYear: 2011132728273421869984
80. MacLeod MJ,Riley WJ,McKone TE. Assessing the influence of climate variability on atmospheric concentrations of persistent organic pollutants using a global-scale mass balance model (BETR-Global)Environ Sci TechnolYear: 2005396749675616190235
81. Royal SocietyYear: 2008 Ground-level ozone in the 21st century: Future trends, impacts, and policy implications. RS Policy document 15/08, London, UK.
82. National Research CouncilArsenic in Drinking WaterYear: 1999Washington, DC, USANational Academy Press
83. Dittmar J,Voegelin A,Roberts LC,Hug SJ,Saha GC,Ali MA,Badruzzaman AB,Kretzschmar R. Spatial distribution and temporal variability of arsenic in irrigated rice fields in Bangladesh paddy soilEnviron Sci TechnolYear: 2007415967597217937268
84. Cousins I,Kong D,Vestergre R. Year: 2011 Impacts of climate change on exposure to POPs for wildlife and humans. UNEP/AMAP Expert Group Report—Climate change and POPs: Predicting the impacts. United Nations Environment Programme/Arctic Monitoring and Assessment Programme, Geneva, Switzerland.
85. Dalla Valle M,Codato E,Marcomini A. Climate change influence on POPs distribution and fate: A case studyChemosphereYear: 2007671287129517258268
86. Schiedek D,Sundelin B,Readman JW,Macdonald RW. Interactions between climate change and contaminantsMar Pollut BullYear: 2007541845185617963794
87. Najjar RG,Pyke CR,Adams MB,Breitburg D,Hershner C,Kempf M,Howarth R,Mulholland MR,Paolisso M,Secor D,Sellner K,Wardrop D,Wood R. Potential climate-change impacts on the Chesapeake BayEstuar Coast Shelf SciYear: 201086120
88. Amato GD,Cecchi L. Effects of climate change on environmental factors in respiratory allergic diseasesClin Exp AllergyYear: 2008381264127418537982
89. International Agency for Research on CancerA Review of Human Carcinogens: Chemical Agents and Related OccupationsYear: 2012Lyon, FranceIARC Monographs on the Evaluation of Carcinogenic Risks to Humans 100F
90. World Health OrganizationImpacts of aflatoxins on health and nutrition. Report of an Expert Group MeetingYear: 2006WHO Regional Office for Africa
91. International Agency for Research on CancerSome Traditional Herbal Medicines, Some Mycotoxins, Naphthalene And StyreneYear: 2002Lyon, FranceIARC Monographs on the Evaluation of Carcinogenic Risks to Humans 82
92. International Agency for Research on CancerSome Naturally Occurring Substances: Food Items And Constituents, Heterocyclic Aromatic Amines And MycotoxinsYear: 1993Lyon, FranceIARC Monographs on the Evaluation of Carcinogenic Risks to Humans 56
93. Mally A,Pepe G,Ravoori S,Fiore M,Gupta RC,Dekant W,Mosesso P. Ochratoxin a causes DNA damage and cytogenetic effects but no DNA adducts in ratsChem Res ToxicolYear: 2005181253126116097798
94. International Agency for Research on CancerIngested Nitrate And Nitrite, And Cyanobacterial Peptide ToxinsYear: 2010Lyon, FranceIARC Monographs on the Evaluation of Carcinogenic Risks to Humans 94. IARC
95. Dietrich D,Hoeger S. Guidance values for microcystins in water and cyanobacterial supplement products (blue-green algal supplements): A reasonable or misguided approachToxicol Appl PharmacolYear: 200520327328915737681
96. Office of Environmental Health Hazard AssessmentToxicological summaries and suggested action levels to reduce potential adverse effects of six cyanotoxinsYear: 2012Sacramento, CA, USA
97. U.S. Environmental Protection AgencyYear: 2006 Air quality criteria for ozone and related photochemical oxidants. U.S. EPA National Center for Environmental Assessment, Research Triangle Park, NC.
98. Office of Environmental Health Hazard AssessmentRecommendation for an air quality standard for ozoneYear: 2004Sacramento, CA, USA
99. U.S. Environmental Protection AgencyMercury study report to congressYear: 1997Washington, DCOffice of Air Quality and Standards and Office of Research and Development
100. National Toxicology Program12th report on carcinogensYear: 2011NC, USADepartment of Health and Humans Services, Research Triangle Park
101. Agency for Toxic Substances and Disease RegistryToxicological profile for polychlorinated biphenyls (PCBs)Year: 2000Atlanta, GA, USACenters for Disease Control and Prevention, Department of Health and Human Services
102. Ziska L,Knowlton K,Rogers C,Dalan D,Tierney N,Elder MA,Filley W,Shropshire J,Ford LB,Hedberg C,Fleetwood P,Hovanky KT,Kavanaugh T,Fulford G,Vrtis RF,Patz JA,Portnoy J,Coates F,Bielory L,Frenz D. Recent warming by latitude associated with increased length of ragweed pollen season in central North AmericaProc Natl Acad Sci USAYear: 20111084248425121368130
103. Sheffield PE,Weinberger KR,Kinney PL. Climate change, aeroallergens, and pediatric allergic diseaseMt Sinai J MedYear: 201178788421259264
104. Beggs PJ. Adaptation to impacts of climate change on aeroallergens and allergic respiratory diseasesInt J Environ Res Public HealthYear: 201073006302120948943
105. D'Amato G,Cecchi L,D'Amato M,Liccardi G. Urban air pollution and climate change as environmental risk factors of respiratory allergy: An updateJ Invest Allerg ClinYear: 20102095102

Figures

[Figure ID: fig01]
Fig. 1 

Source–pathway–receptor relationship, showing interactions with both climate and nonclimate stressors. GCC = global climate change. [Color figure can be seen in the online version of this article, available at http://wileyonlinelibrary.com]



Tables
[TableWrap ID: tbl1] Table 1 

Potential effects of global climate change (GCC) on human exposures from major chemical contaminant sources


Contaminant of concern Relative importance of environmental exposure pathways compared to other pathways (e.g., direct use, occupational) Major sources Direct and indirect effects of GCC on contaminant source Direct and indirect effects of GCC on fate and transport Overall effect of GCC on human environmental exposure Evidence base for climate impact
Criteria air pollutants SO2, NOx, PMx High Automobiles, chemical production sites, power stations, incinerators, residences Emissions of many air pollutants harmful to human health may be lower if society mitigates against greenhouse gas emissions by moving toward biofuels 72. Emissions may increase at biofuel production sites 20. Limited Adverse/positive High
Ground-level O3 High Precursor gases NOx, VOCs, and CO If global carbon emission controls are implemented, a reduction in ozone is predicted in developed areas, but an increase is expected in developing countries. If controls are not implemented, exposure will increase globally. An increase expected in number of pollution days is also expected 81. Limited Adverse/positive High
Arsenic High Natural contamination Altered climates that impact the microbial communities and water chemistry of freshwater systems can affect the distribution of arsenic species in surface water 82. Increased irrigation results in greater contamination of food crops 83. Adverse High
Mercury High Contaminated soils and sediments Altered climates may affect microbial biotransformation of mercury from the divalent to the more biologically available organic species 33. Increases in temperature may increase Hg mobility as a result of increased conversion of Hg species to vapor Hg and to methyl mercury 80. Uptake into fish expected to increase 33. Adverse High
Dioxins, PCBs, DDT High Waste sites, combustion, electrical equipment, forest fires Increasing temperatures will increase the release of POPs from sources such as buildings and electrical equipment 27. Use of DDT may increase due to increased need for malaria control 27. Thawing of ice caps will release persistent organic compounds. Increases in flooding events will remobilize soil- and sediment-associated POPs and transport them to uncontaminated areas 18. Uptake into fish may increase or decrease 84. Degradation of some POPs will increase in some areas 85 Adverse High
Pesticides Medium Agriculture Outbreaks of a wider variety of insects and pathogens is expected, resulting in increased pesticide use and changes in application timings 58. Geographical shifts in agriculture will mean that cropping patterns change and types of pesticide use change 86. Increased volatilization of pesticides expected following application 1. Degradation in soils may increase due to increased temperatures and changes in soil moisture 25. Adverse—bystander exposure anticipated to increase Medium
Pharmaceuticals Low Health care Increases in human diseases (e.g., malaria, depression) may result in increasing pharmaceutical use. Increased recycling of water and use of treated wastewater for irrigation may result in entry into food items. Adverse Low
Veterinary drugs Low Agriculture The proliferation of animal diseases due to climate-related changes may result in an increased use of veterinary drugs that could lead to increased releases to the environment 18. Degradation in soils may increase due to increased temperatures and changes in soil moisture 25. Adverse Medium
Industrial process chemicals Low Industrial facilities Increased catastrophic weather events (floods, wildfires) may result in increased catastrophic accidental releases. Limited Adverse Low
Algal toxins High Algal blooms Warmer conditions are generally linked to increased frequency, duration, and geographic scope of HABs, due to changes in water temperatures and stratification and increased nutrient inputs, so GCC is predicted to increase the incidence of HABs in the future 18, 23, 86, 87 Limited Adverse High
Mycotoxins High Fungi-infected crops Mycotoxin contamination of crops is anticipated to increase due to drought stress, temperature stress, stress induced by pest attack, increases in arthropod vectors, poor nutrient status 54, 86. Changes in the geographical range of crops produced could provide opportunity for new fungus–plant associations to arise, so mycotoxins currently not considered a threat to public health (e.g., sterigmatocystin, cyclopiazonic acid, moniliformin) may become important 18. Limited Adverse High
Pollen High Plants GCC is predicted to lengthen the pollen season as well as increase pollen and spore rupture; increase in pollen allergenicity 22, 88 Increase in long-distance transport Adverse High

SO2 = sulfur dioxide; NOx = nitrogen oxide; PMx= particulate matter; O3 = ozone; VOC = volatile organic compound; CO = carbon monoxide; Hg = mercury; POP = persistent organic pollutant; PCB = polychlorinated biphenyl; DDT = dichlorodiphenyltrichloroethane; HAB = harmful algal blooms


[TableWrap ID: tbl2] Table 2 

Health effects and vulnerable populations for selected environmental exposures potentially affected by climate change


Stressors Health effects Possible most heavily impacted populations or regions Confidence in or evidence for effects
Mycotoxin residues in foods (effects indicated are for aflatoxins) Carcinogenicity, hepatotoxicity, immunosuppression, developmental toxicity 89, 90, and possible male fertility deficits Developing areas of Africa, Asia, and South America with high concentrations of relatively uncontrolled mycotoxin exposure Sufficient evidence for carcinogenicity in humans for aflatoxins 89 and in animals for fumonisins 91 and ochratoxin 92, 93. Suggestive evidence of reproductive toxicity in humans.
Algal toxins (entries in table are for the blue-green algae toxin microcystin-LR) Severe gastroenteritis, liver toxicity, blistering of mucous membranes, possible immunotoxicity, possibly carcinogenic 9496 Those recreating in eutrophic water that harbor algal cyanobacterial populations; people on water supplies from sources that harbor the bacteria but are not adequately treated (disinfection can be insufficient); greater consumption of contaminated fish, shellfish, and crayfish by those with lower income. Because they are stable to heat and acid, food preparation does not protect consumers of contaminated fish or shellfish. Carcinogenicity conclusion of systematic IARC review 94; noncancer evidence from documented episodes of human poisoning as well as from animal experiments
Ozone Asthma exacerbation, chronic pulmonary obstructive disorder, cardiovascular and pulmonary disease 97, 98 People with preexisting health conditions such as asthma; people in communities and developing countries with existent high concentrations of ozone; in US, urban centers in the mid-Atlantic and northeast. Clear evidence from studies in humans
Methylmercury Neurotoxicity 99 Fetus and young more impacted at same dose than adults; subsistence fishers Clear evidence in humans of neurotoxicity in adults and the young
Polyhalogenated biphenyls, dioxins, furans, and other halogenated POPs Carcinogenicity, endocrine toxicity, neurotoxicity, reproductive toxicity 89, 100, 101 Fetus and young more impacted by thyroid hormone–related toxicity pathways; susceptibility of native populations (e.g., Arctic) Dioxin is a known human carcinogen 89. There is sufficient animal evidence supporting the potential carcinogenicity of many POPs 100. There is a large volume of evidence supporting endocrine toxicity for many POPs, such as PCBs 101.
Pollens Asthma, allergic rhinitis 102105 Children and older adults Increase in temperature associated with increased pollen and increased percentages of patients sensitized to pollens have been observed, but good epidemiologic evidence is lacking 22.

GCC = global climate change; IARC = International Agency for Research on Cancer; POP = persistent organic pollutant; PCB = polychlorinated biphenyl; PMx = particulate matter; SO2 = sulfur dioxide; VOC = volatile organic compound.


[TableWrap ID: tbl3] Table 3 

Impacts of global climate change (GCC) on different assessment or management processes for natural toxins


Decision question being asked Who? How is the decision made now? What will be the implications of GCC on the decision-making process? Probability and magnitude of GCC impact What other changes might take place? Recommendation
Monitoring
Is the level of a natural toxin (e.g., mycotoxin or algal toxin) safe? Regulatory and public-health agencies, food industry Occurrence of some natural toxins is measured in food samples and concentrations are compared to a standard or advisory guideline. Outbreaks of fungal infections and algal blooms will occur more frequently under GCC. More rigorous monitoring may be required to pick up exceedances. High probability in some regions, high magnitude None anticipated Modeling studies to explore likely prevalence of natural toxin food contamination incidents in different regions and evaluation of existing monitoring regimes against these predictions.
Strategic forecasting
Do natural toxins pose a threat to food security? Regulatory and public-health agencies, public-health researchers Analysis of monitoring data on the occurrence of natural toxins in food Outbreaks of fungal infections and algal blooms will occur more frequently under GCC, resulting in reduction in the availability of safe food in some regions. High probability, magnitude of changes uncertain None anticipated Apply plant infection models that account for climatic effects for different regions under GCC.
Apply modeling to explore likely increases in algal blooms under GCC in different regions.

[TableWrap ID: tbl4] Table 4 

Impacts of global climate change (GCC) on different assessment or management processes for pesticides


Decision question being asked Who? How is the question answered now? What are the implications of GCC on the assessment or decision process? Probability and magnitude of GCC impact What other changes might take place? Recommendation
Standard setting
What is a safe concentration of a pesticide on food? Regulatory and public-health agencies Acceptable dose is determined from dose–response studies. Increased vulnerability of population may require lower standard or guideline. Medium, may be high for particular subpopulations New research may change toxicological risk estimates Toxicologic studies with climate costressors and adaptation of methods for estimating acceptable doses.
Dietary consumption patterns are used with dose data to establish acceptable concentration standard or guideline. GCC may impact food production and, hence, availability of certain food types, changing dietary patterns. High probability, high magnitude for some regions; low/medium for others Diets may change due to cost or nutritional needs; world economic crisis could occur, resulting in higher food prices; transportation of food may become more costly because of energy costs and carbon taxes. Dietary consumption should be recalculated more frequently and for vulnerable regions and subpopulations.
Monitoring
Is the concentration of pesticide in the food supply safe? Regulatory and public-health agencies, food industry Pesticide residues are measured in food samples, and concentrations are compared to tolerance standard or guideline Pesticide applications may occur more frequently under GCC. More rigorous monitoring may be required to pick up exceedances. Medium probability, medium magnitude Safer product may be substituted for current pesticide; new pest-management techniques may be adopted; organic farming may become more widespread. Modeling studies to explore likely changes in occurrence of pesticides in food under GCC in different regions and evaluation of existing monitoring regimes against these predictions.
Product risk assessment
What will be the risk of a new pesticide to humans via food? Regulatory and public-health agencies, pesticide registrants Predict pesticide concentrations in food based on expected uses. New pathways of exposure (e.g., dust) may occur that are not currently modeled; Low; registrants may anticipate major GCC impacts through market demand studies. Changes in market demand may result in dietary exposures that are different from those predicted. Test food samples for residues on a regular basis.
existing model algorithms may fall down under GCC extremes.
Predict exposure based on dietary information. Diets may change under GCC. High for some regions, low/medium for others Economic factors may alter dietary choices. Conduct periodic food-consumption surveys.
Compare predicted exposures to toxicologic data. Increased vulnerability may mean current assumptions in risk assessment are no longer valid. Low/medium, high uncertainty New scientific studies may alter risk-assessment inputs Regularly review scientific literature on vulnerability under GCC
Strategic forecasting
Will we be able to access food that is safe from pesticides in the future? Regulatory and public-health agencies, public-health researchers Periodic updates of risk assessments Increased pesticide use and irrigation practices may increase residues in food. Increased UV may decrease residues. High probability, magnitude of changes uncertain. Economic factors may limit the ability to collect sufficient data for risk assessments. Provide support for data collection, conduct reregistration reviews more frequently.
Safe concentrations may change (see above).

UV = ultraviolet.


[TableWrap ID: tbl5] Table 5 

Impacts of global climate change (GCC) on different assessment or management processes for air pollutants


Decision question being asked Who? How is the decision question answered now? What will be the implications of GCC on the decision-making process? Probability and magnitude of GCC impact What other changes might take place? Recommendation
Standard setting
What is a reasonably safe concentration of a criteria air pollutant with respect to human health? Regulatory and public-health agencies and scientific advisory entities, affected industries Acceptable concentration is determined from meta-analysis of epidemiologic studies GCC will have mixed impacts on primary and secondary pollutant levels; may affect population vulnerability through costressors (heat) or secondary effects (nutrition, stress); will affect validity of models used for regulatory justification. High probability; magnitude of impact uncertain; small magnitude could have large public-health consequences for PM2.5 and ozone. Changing technologies for energy generation and transportation; changing land-use and agricultural practices; GCC mitigation measures in general likely to reduce emissions of criteria air pollutants. This may be offset to a certain extent by population growth. Research needs: (1) laboratory simulations to determine effects of temperature and other atmospheric parameters on secondary pollutants, especially particulates; (2) studies of interactions of weather parameters and pollutant exposures in humans; (3) controlled human clinical studies of temperature impact on pollutant toxicity.
Practice needs: updating of weather models in regulatory justifications, ensuring that weather models reflect current and future trends in variability, extreme events, air stagnation, events, etc.
What is a reasonably safe concentration for criteria air pollutants with respect to human welfare? Regulatory and public-health agencies Acceptable concentration is based on consideration of a wide array of scientific literature on the effects of criteria air pollutants on ecosystems, crops, and other receptors linked to human economic well-being and indirectly to health GCC is likely to alter the vulnerability of many ecosystems and plant species to criteria air pollutants (e.g., ozone) due to costressors, including pests and diseases. High probability, likely high impact Technological advances in genetically engineered crops to resist heat, drought, and pests. Changes in agricultural practices and recreational patterns. Maintain and strengthen programs that evaluate ecosystem health; document changes due to climate, agricultural, and recreational patterns.
Monitoring
What are the concentrations of air pollutants in critical geographical areas? Regulatory, health, and resource-management agencies Monitoring conducted primarily for regulatory compliance purposes, frequency and location determined by statutes or regulations, and guidance developed by stakeholder processes; monitoring for research conducted on an ad hoc basis. Changing distribution of air pollutants may shift most important places for monitoring; GCC will require more frequent monitoring. High probability, low to moderate impact For developing countries, unclear to what extent satellite-based monitoring will be developed Research needs: (1) for developing countries, improved satellite monitoring methods; improved, cheaper surface-based monitoring devices.
Practice needs: expanded air-quality monitoring in developing countries
Product risk assessment
What are the human health risks associated with fuel additives, biofuels, and other new technologies intended to reduce greenhouse gas emissions? Regulatory agencies, producers Laboratory testing of product and characterization of by-products of combustion; standard toxicological risk assessment based on modeled exposures and toxicity tests. Primarily related as a technological intervention to address the problems of GCC; future GCC may affect use patterns as well as dispersion models used to estimate human exposures. High probability, low impact Technological developments not driven by GCC Use realistic ranges for future use scenarios, avoiding historical errors of underestimates of market penetration and use; ensure dispersion and exposure models are robust for future climate parameters.
Strategic forecasting
What policy options for reducing greenhouse gas emissions offer the greatest human health cobenefits through reduction of toxic criteria air pollutants? Regulatory and public-health agencies, academic researchers, expert consultants, industry Process involves individual policy analysis, primarily through NEPA; use of linked risk-assessment models like BenMAP or integrated assessment models Feedback loops of GCC on factors in integrated assessments such as economic vitality, patterns of energy consumption and transportation use; impacts of altered climate on current dispersion and exposure models High probability, uncertain impact Concurrent changes in many factors, including economic, social, underlying health status, demographics, technologies Research needs: improved integrated assessment models with improved modules for human health risk assessment

NEPA = National Environmental Policy Act; PMx, = particulate matter.


[TableWrap ID: tbl6] Table 6 

Impacts of global climate change (GCC) on different assessment or management processes for legacy pollutants


Decision question being asked Who? How is the decision question now answered? What will be the implications of GCC on the decision-making process? Probability and magnitude of GCC impact What other changes might take place? Recommendation
Monitoring
What are the concentrations of legacy pollutants in the environment and food supply? Regional, national, and international regulatory and public-health agencies Legacy pollutants such as mercury and legacy POPs are tracked in air, water, soil, food, and biota. There is also a strong reliance on fate modeling to interpret future trends and provide more spatial resolution. Legacy pollutants can be more easily mobilized by climate disruption and can have altered phase distributions in warmer climates. High probability of change in higher latitudes and at higher elevations. Moderate probability of change in other regions. Higher-resolution environmental and biospecimen monitoring capacity Expanded modeling studies combined with strategic environmental sampling to track the magnitude and variation of altered transport patterns for legacy pollutants, particularly in higher latitudes. Careful attention to food-web contamination is needed.
Strategic forecasting
How safe are the levels of legacy pollutants in the food supply and breast milk? Regional, national, and international regulatory and public-health agencies Analysis of food concentrations compared to guideline levels established using data from toxicological tests and predicted food concentrations Food commodities in some regions, particularly for subsistence populations, may need to be replaced or consumption curtailed; fish advisories and other public information programs likely will also be affected. High probability of increased exposure, but significant geographic and population variability are likely. Availability of seafood could be more substantially impacted by GCC or overfishing than anticipated. Decision makers should exercise adaptive management to address changes, based on effective use of expanded models and limited observations. Models used to support selection of chemicals of concern for the Stockholm Convention on POPs should be reevaluated.

POP = persistent organic pollutant.



Article Categories:
  • Global Climate Change

Keywords: Toxicology, Exposure pathway, Risk assessment, Vulnerability.

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