Document Detail


Assessing isocyanate exposures in polyurethane industry sectors using biological and air monitoring methods.
MedLine Citation:
PMID:  16731584     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Isocyanates, as a chemical group, are considered to be the biggest cause of occupational asthma in the UK. Monitoring of airborne exposures to total isocyanate is costly, requiring considerable expertise, both in terms of sample collection and chemical analysis and cannot be used to assess the effectiveness of protection from wearing respiratory protective equipment (RPE). Biological monitoring by analysis of metabolites in urine can be a relatively simple and inexpensive way to assess exposure to isocyanates. It may also be a useful way to evaluate the effectiveness of control measures in place. In this study biological and inhalation monitoring were undertaken to assess exposure in a variety of workplaces in the non-motor vehicle repair sector. Companies selected to participate in the survey included only those judged to be using good working practices when using isocyanate formulations. This included companies that used isocyanates to produce moulded polyurethane products, insulation material and those involved in industrial painting. Air samples were collected by personal monitoring and were analysed for total isocyanate content. Urine samples were collected soon after exposure and analysed for the metabolites of different isocyanate species, allowing calculation of the total metabolite concentration. Details of the control measures used and observed contamination of exposed skin were also recorded. A total of 21 companies agreed to participate in the study, with exposure measurements being collected from 22 sites. The airborne isocyanate concentrations were generally very low (range 0.0005-0.066 mg m(-3)). A total of 50 of the 70 samples were <0.001 mg m(-3), the limit of quantification (LOQ), therefore samples below the LOQ were assigned a value of 1/2 LOQ (0.0005 mg m(-3)). Of the 70 samples, 67 were below the current workplace exposure limit of 0.02 mg m(-3). The highest inhalation exposures occurred during spray painting activities in a truck manufacturing company (0.066 mg m(-3)) and also during spray application of polyurethane foam insulation (0.023 mg m(-3)). The most commonly detected isocyanate in the urine was hexamethylene diisocyanate, which was detected in 21 instances. The geometric mean total isocyanate metabolite concentration for the dataset was 0.29 micromol mol(-1) creatinine (range 0.05-12.64 micromol mol(-1) creatinine). A total of 23 samples collected were above the agreed biological monitoring guidance value of 1.0 micromol mol(-1) creatinine. Activities that resulted in the highest biological monitoring results of the dataset included mixing and casting of polyurethane products (12.64 micromol mol(-1) creatinine), semi-automatic moulding (4.80 micromol mol(-1) creatinine) and resin application (3.91 micromol mol(-1) creatinine). The biological monitoring results show that despite low airborne isocyanate concentrations, it was possible to demonstrate biological uptake. This tends to suggest high sensitivity of the biological monitoring method and/or that in some instances the RPE being used by operators was not effective or that absorption may have occurred via dermal or other routes of exposure. This study demonstrates that biological monitoring is a useful tool when assessing worker exposure to isocyanates, providing a more complete picture on the efficacy of control measures in place than is possible by air monitoring alone. The results also demonstrated that where control measures were judged to be adequate, most biological samples were close to or < 1 micromol mol(-1) creatinine, the agreed biological monitoring benchmark.
Authors:
K S Creely; G W Hughson; J Cocker; K Jones
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-05-26
Journal Detail:
Title:  The Annals of occupational hygiene     Volume:  50     ISSN:  0003-4878     ISO Abbreviation:  Ann Occup Hyg     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-08-18     Completed Date:  2007-10-12     Revised Date:  2008-04-16    
Medline Journal Info:
Nlm Unique ID:  0203526     Medline TA:  Ann Occup Hyg     Country:  England    
Other Details:
Languages:  eng     Pagination:  609-21     Citation Subset:  IM    
Affiliation:
Institute of Occupational Medicine, Research Avenue North, Riccarton, Edinburgh, UK. karen.creely@iom-world.org
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MeSH Terms
Descriptor/Qualifier:
Air Pollutants, Occupational / analysis*
Biological Markers / urine
Environmental Monitoring / methods*
Humans
Inhalation Exposure / analysis
Isocyanates / administration & dosage*,  analysis
Occupational Exposure / analysis*
Polyurethanes
Chemical
Reg. No./Substance:
0/Air Pollutants, Occupational; 0/Biological Markers; 0/Isocyanates; 0/Polyurethanes; 9009-54-5/polyurethane foam
Comments/Corrections
Comment In:
Ann Occup Hyg. 2007 Oct;51(7):645-6; author reply 646-9   [PMID:  17905735 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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