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Occupational Exposure Limit (occupational + exposure_limit)
Selected AbstractsUrinary 1-hydroxypyrene concentrations in Chinese coke oven workers relative to job category, respirator usage, and cigarette smokingAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 9 2007Bo Chen PhD Abstract Background 1-Hydroxypyrene (1-OHP) is a biomarker of recent exposure to polycyclic aromatic hydrocarbons (PAHs). We investigated whether urinary 1-OHP concentrations in Chinese coke oven workers (COWs) are modulated by job category, respirator usage, and cigarette smoking. Methods The present cross-sectional study measured urinary 1-OHP concentrations in 197 COWs from Coking plant I and 250 COWs from Coking plant II, as well as 220 unexposed referents from Control plant I and 56 referents from Control plant II. Results Urinary 1-OHP concentrations (geometric mean, µmol/mol creatinine) were 5.18 and 4.21 in workers from Coking plants I and II, respectively. The highest 1-OHP levels in urine were found among topside workers including lidmen, tar chasers, and whistlers. Benchmen had higher 1-OHP levels than other workers at the sideoven. Above 75% of the COWs exceeded the recommended occupational exposure limit of 2.3 µmol/mol creatinine. Respirator usage and increased body mass index (BMI) slightly reduced 1-OHP levels in COWs (P,<,0.1). Cigarette smoking significantly increased urinary 1-OHP levels in unexposed referents (P,<,0.005), but had no effect in COWs (P,>,0.1). Conclusions Chinese COWs, especially topside workers and benchmen, are exposed to high levels of PAHs. Urinary 1-OHP concentrations appear to be modulated by respirator usage and BMI in COWs, as well as by smoking in unexposed referents. Am. J. Ind. Med. 50:657,663, 2007. © 2007 Wiley-Liss, Inc. [source] A Note on Comparing Exposure Data to a Regulatory Limit in the Presence of Unexposed and a Limit of DetectionBIOMETRICAL JOURNAL, Issue 6 2005Haitao Chu Abstract In some occupational health studies, observations occur in both exposed and unexposed individuals. If the levels of all exposed individuals have been detected, a two-part zero-inflated log-normal model is usually recommended, which assumes that the data has a probability mass at zero for unexposed individuals and a continuous response for values greater than zero for exposed individuals. However, many quantitative exposure measurements are subject to left censoring due to values falling below assay detection limits. A zero-inflated log-normal mixture model is suggested in this situation since unexposed zeros are not distinguishable from those exposed with values below detection limits. In the context of this mixture distribution, the information contributed by values falling below a fixed detection limit is used only to estimate the probability of unexposed. We consider sample size and statistical power calculation when comparing the median of exposed measurements to a regulatory limit. We calculate the required sample size for the data presented in a recent paper comparing the benzene TWA exposure data to a regulatory occupational exposure limit. A simulation study is conducted to investigate the performance of the proposed sample size calculation methods. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Mixture Model for Occupational Exposure Mean Testing with a Limit of DetectionBIOMETRICS, Issue 3 2001Douglas J. Taylor Summary. Information from detectable exposure measurements randomly sampled from a left-truncated log-normal distribution may be used to evaluate the distribution of nondetectable values that fall below an analytic limit of detection. If the proportion of nondetects is larger than expected under log normality, alternative models to account for these unobserved data should be considered. We discuss one such model that incorporates a mixture of true zero exposures and a log-normal distribution with possible left censoring, previously considered in a different context by Moulton and Halsey (1995, Biometrics51, 1570,1578). A particular relationship is demonstrated between maximum likelihood parameter estimates based on this mixture model and those assuming either left-truncated or left-censored data. These results emphasize the need for caution when choosing a model to fit data involving nondetectable values. A one-sided likelihood ratio test for comparing mean exposure under the mixture model to an occupational exposure limit is then developed and evaluated via simulations. An example demonstrates the potential impact of specifying an incorrect model for the nondetectable values. [source] Personnel breathing zone sevoflurane concentration adherence to occupational exposure limits in conjunction with filling of vaporisersACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 9 2010H. HEIJBEL Background: Work place pollution during filling of anaesthetic vaporisers has been a matter of concern. We studied personnel breathing zone ambient air sevoflurane concentrations during filling of sevoflurane with three different filling systems: Quik-FilÔ for Abbott and Dräger FillÔ resp. Easy-FilÔ adapters for Baxter sevoflurane bottles, referred to as ,Abbott and Baxter filling systems'. Method: Sequential filling of three vaporisers was performed for a 15-min period, once with each of Abbott and Baxter filling systems, by four nurses. Ambient-air sevoflurane p.p.m. concentration in the breathing zone was continuously measured using a Miran 1a device during filling, and the mean 15 min sevoflurane concentration was calculated. Results: All eight measured (4 × 2 sequences) 15-min mean breathing zone sevoflurane concentrations covering filling of three vaporisers were well below the recommended short-term value (STV) provided by the Swedish Work Environment Authority (STV 20 p.p.m.). Conclusion: The breathing zone sevoflurane concentration during filling of sevoflurane with Baxter or Abbott filling systems, in an ordinary operating theatre, was found to be reassuringly below the Swedish recommended STV (20 p.p.m. average for a 15-min period). [source] Reassessment of occupational exposure limitsAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 6 2008Hans Stouten MSc Abstract Background Although the Netherlands currently has its own procedure for evaluating chemical compounds and setting occupational exposure limits (OELs), most of these limits were originally adopted in the 1970s from threshold limit values (TLVs) set by the American Conference of Governmental Industrial Hygienists (ACGIH). However, beginning in the late 1980s, criticism about non-scientific considerations being used to set TLV's suggested that TLVs might not offer sufficient health protection to workers. This situation prompted the Dutch Ministry of Social Affairs and Employment to request that the Health Council of the Netherlands reassess the health protection of MAC values that were contained in the 1994 Dutch MAC list. Methods Criteria documents were prepared for 161 compounds. They were evaluated by a committee of the Health Council of the Netherlands consisting of international experts who reassessed the toxicological hazards of these substances and recommended, whenever possible, health-based OELs. The results of the reassessment by the Health Council were compared with the MAC values of the 1994 Dutch MAC list, ACGIH TLVs, and existing German OELs. Results The toxicological database met the committee's criteria for a health-based OEL for only about 40% of the compounds. Conclusions Many older MAC values were either too high or not scientifically supported and therefore not health-based. Am. J. Ind. Med. 51:407,418, 2008. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||