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Observed versus predicted carboxyhemoglobin levels in cellulose triacetate workers exposed to methylene chloride
Author(s) -
Amsel Jon,
Soden Kevin J.,
Sielken Robert L.,
ValdezFlora Ciriaco
Publication year - 2001
Publication title -
american journal of industrial medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.7
H-Index - 104
eISSN - 1097-0274
pISSN - 0271-3586
DOI - 10.1002/ajim.1086
Subject(s) - carboxyhemoglobin , cellulose triacetate , medicine , methylene , chloride , threshold limit value , pharmacokinetics , toxicology , physiology , carbon monoxide , anesthesia , pharmacology , chemistry , environmental health , organic chemistry , cellulose , biology , catalysis
Background Occupational exposure to methylene chloride, together with carboxyhemoglobin concentrations, has not been studied previously. Methods Carboxyhemoglobin levels were measured in non‐smoking employees exposed to varying concentrations of methylene chloride during the manufacture of cellulose triacetate fibers. The observed carboxyhemoglobin levels were compared to predicted concentrations using a pharmacokinetic model. Results The presence of carboxyhemoglobin in non‐smokers exposed to methylene chloride results primarily from the metabolism of methylene chloride in the liver and exhibits a linear dose‐response relationship. The observed levels of carboxyhemoglobin in non‐smokers at the end of an 8‐hour shift depend upon exposures to methylene chloride that day but are independent of occupational exposures on previous days. The observed daily concentrations of carboxyhemoglobin are consistent with predicted concentrations using a pharmacokinetic model. While varying exposure patterns were shown to change the rate of metabolite formation at the end of shift, these same exposure patterns had almost no effect on the total amount of carbon monoxide in the blood. Conclusion While the present study addresses the relationship between methylene chloride, carbon monoxide, carboxyhemoglobin and ischemic heart disease, it does not address the issue of tumorigenicity, which is also the basis for the current U.S. Occupational Health and Safety workplace exposure limit of 25 ppm. This study provides support for the conclusion that the current American Conference of Governmental Industrial Hygienists 8‐hour Threshold Limit Value of 50 ppm adequately protects human health with regard to ischemic heart disease and carboxyhemoglobin formation among non‐smokers. Am. J. Ind. Med. 40:180–191, 2001. © 2001 Wiley‐Liss, Inc.