Daniel Drolet

Creatinine and Specific Gravity Normalization in Biological Monitoring of Occupational Exposures

Reference values for the biological monitoring of occupational exposures are generally normalized on the basis of creatinine (CR) concentration or specific gravity (SG) to account for fluctuations in urine dilution. For instance, the American Conference of Governmental Industrial Hygienists (ACGIH®) uses a reference value of 1g/L for CR. The comparison of urinary concentrations of biomarkers between studies requires the adjustment of results based on a reference CR and/or SG value, although studies have suggested that age, sex, muscle mass, and time of the day can exert non-negligible influences on CR excretion, while SG appears to be less affected. The objective of this study was to propose reference values for urinary CR and SG based on the results of samples sent for analysis by occupational health practitioners to the laboratory of the Occupational Health and Safety Research Institute of Québec (IRSST). We analyzed a database containing 20,395 urinary sample results collected between 1985 and 2010. Linear mixed-effects models with worker as a random effect were used to estimate the influence of sex and collection period on urinary CR and SG. Median CR concentrations were 25–30% higher in men (1.6 g/L or 14.4 mmol/L) than in women (1.2 g/L or 10.2 mmol/L). Four percent of the samples for men and 12% for women were below the acceptable threshold for CR (4.4 mmol/L). For SG, 5% of samples for men and 12% for women were below the threshold of 1.010. The difference in SG levels between sexes was lower than for CR, with a median of 1.024 for men compared to 1.020 for women. Our results suggest that the normalization of reference values based on a standard CR value of 1 g/L as proposed by the ACGIH is a conservative approach. According to the literature, CR excretion is more influenced by physiological parameters than SG. We therefore suggest that correction based on SG should be favored in future studies involving the proposal of reference values for the biological monitoring of occupational exposures.

A Web Tool for the Identification of Potential Interactive Effects of Chemical Mixtures

This project was undertaken to develop a toxicological database allowing the identification of possible additive or other interactive effects of mixtures present in the work environment. In the first phase of the project, whose findings have already been published, critical toxicological data were compiled for each of the 695 chemical substances in the Quebec Occupational Health Regulation, allowing the prediction of potential additivity among components of a mixture. In the second phase of this project, the types of interactions for mixtures most likely to be found in workplaces and for which primary literature data are available were specified. The toxicological data were evaluated only for realistic exposure concentrations up to the short-term exposure limit or ceiling value or five times the 8-hr time-weighted average (TWA) permissible exposure limit (PEL) for human data and up to 100 times the 8-hr TWA PEL or ceiling value for animal studies. In total, 675 studies were evaluated covering 209 binary mixtures of substances. For the majority of cases where potential additivity was identified in Phase 1, there is a lack of toxicological data in the primary literature. In these cases, the results of the first phase will be useful as the default hypothesis. The resulting database integrates the results from both phases of the project. A web-based computer tool allows the user to determine whether there is potential additivity or interaction among components of a mixture.

Database for the toxicological evaluation of mixtures in occupational atmospheres.

Workers are regularly simultaneously exposed to multiple chemical substances. As in the ACGIH (American Conference of Governmental Industrial Hygienists) approach, the Québec Regulation prescribes that when two or more hazardous substances are present in workplaces and have similar effects on the same organs of the human body, their effects should be considered additive, unless established otherwise. This project was undertaken to develop a user-friendly toxicological database aid in identification of possible interactive effects of mixtures present in the work environment. In the first phase of the project, standard general literature references were used to compile critical data, such as target organs, effects on the target organs, mechanisms of action, and toxicokinetic characteristics of each of the 668 chemical substances appearing in the regulation. Each substance was assigned to one or more of 32 classes of biological effects retained by a group of toxicologists. The resulting database allows the user to find if there is potential additivity among components of a mixture.

A study on the substitution of trichloroethylene as a spot remover in the textile industry.

Since the ban on 1,1,1-trichloroethane, the textile industry has been using trichloroethylene (TCE) as a spot remover to clean oil and grease stains from fabrics at inspection stations. TCE is a toxic substance recently classified as a probable human carcinogen. The purpose of this study was to use a systematic substitution procedure to replace TCE with a less hazardous option for spot removing in a textile company. After documenting the problem and understanding the processes involved, numerous sources of information were searched to identify the greatest number of plausible solutions. Then criteria were established to help consider only the options that seemed technically acceptable. Five options were retained: 1-bromopropane, a petroleum-based solvent, a hydrochlorofluorocarbon-based solvent, an appliance that uses hot steam, and the elimination of the oil and grease spots at the source. The latter option, which had been partially implemented by the textile company, was not considered in this study. After being tested in the workplace and evaluated on their technical plausibility and impact on health, safety, and environment, the remaining four options were not considered as suitable replacements for TCE. Thus, local ventilation with the implementation of further measures for the reduction/elimination of stains at the source were recommended to lower TCE exposure for workers.

Determination of N-Nitroso Compounds in the Environment of a Metal Factory Using Metalworking Fluids

Abstract By use of GLC-ECD and HPLC-TEA techniques for N-nitroso compounds, N-nitroso-diethanolamine (NDELA) has been found in concentrations of 1.4–6.0 μg/m3 and 1.3–5.0μg/m3 respectively in all four air samples collected in the environment of a metalworking plant during metallurgical operations. NDELA was quantitated in air samples by GLC-ECD after converting it to its trifluoroacetyl derivative by reaction with the appropriate anhydride. NDELA was analyzed without derivatization in air samples using HPLC-TEA method. N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were also identified and later determined in two out of four air samples in concentrations of 0.08μg/m3 (for NDMA in both samples) and 0.14–0.16μg/m3 (for NDEA) using GLC-TEA procedure. The described method did not cause artifactual formation of N-nitrosomethyl-N-butylamine (NMBA) when methyl-N-butylamine was used as an internal marker of nitrosation during collection of NDELA in impinger traps.

Using checklists and algorithms to improve qualitative exposure judgment accuracy

ABSTRACT Most exposure assessments are conducted without the aid of robust personal exposure data and are based instead on qualitative inputs such as education and experience, training, documentation on the process chemicals, tasks and equipment, and other information. Qualitative assessments determine whether there is any follow-up, and influence the type that occurs, such as quantitative sampling, worker training, and implementing exposure and risk management measures. Accurate qualitative exposure judgments ensure appropriate follow-up that in turn ensures appropriate exposure management. Studies suggest that qualitative judgment accuracy is low. A qualitative exposure assessment Checklist tool was developed to guide the application of a set of heuristics to aid decision making. Practicing hygienists (n = 39) and novice industrial hygienists (n = 8) were recruited for a study evaluating the influence of the Checklist on exposure judgment accuracy. Participants generated 85 pre-training judgments and 195 Checklist-guided judgments. Pre-training judgment accuracy was low (33%) and not statistically significantly different from random chance. A tendency for IHs to underestimate the true exposure was observed. Exposure judgment accuracy improved significantly (p <0.001) to 63% when aided by the Checklist. Qualitative judgments guided by the Checklist tool were categorically accurate or over-estimated the true exposure by one category 70% of the time. The overall magnitude of exposure judgment precision also improved following training. Fleiss’ κ, evaluating inter-rater agreement between novice assessors was fair to moderate (κ = 0.39). Cohens weighted and unweighted κ were good to excellent for novice (0.77 and 0.80) and practicing IHs (0.73 and 0.89), respectively. Checklist judgment accuracy was similar to quantitative exposure judgment accuracy observed in studies of similar design using personal exposure measurements, suggesting that the tool could be useful in developing informed priors and further demonstrating its usefulness in producing accurate qualitative exposure judgments.

Urinary Excretion of Thioethers Related to Styrene Exposure

Urinary Excretion of Thioethers Related to Styrene Exposure: Ginette Truchon et al. Institut de recherche en santé et en sécurité du travail, Montréal, Québec, Canada—The objective of this study was to test the suitability of styrene‐specific mercapturic acids as urinary bioindicators of occupational styrene exposure. The excretion of mandelic acid (MA), global thioethers and styrene‐specific mercapturic acids was measured in urine samples from 64 workers employed in three companies fabricating glass fiber‐reinforced polyester products. Global thioethers were measured by a spectrophotometric method while MA and specific mercapturic acids, N‐acetyl‐S‐(1‐phenyl‐2‐hydroxyethyl)‐L‐cysteine (M1) and N‐acetyl‐S‐(2‐phenyl‐2‐hydroxyethyl)‐L‐cysteine (M2), were measured by high pressure liquid chromatography with UV detection. Excretion of M1 and M2 was qualitatively verified by gas chromatography‐mass spectrometry. The environmental measurements were carried out with passive dosimeters. Workers had 8‐h TWA exposure levels ranging from 0 to 667 mg/m3. End‐of‐shift MA excretion ranged from 0 to 2.08 mmol/mmol creatinine and was well correlated with environmental styrene exposure (r=0.91, p<0.001). M1 and M2 were detected (i.e. above ca. 1 μmol/mmol creatinine) in urine samples of only three workers who were exposed to various concentrations of styrene. End‐of‐shift excretion of global thioethers was found to be significantly correlated to cigarette consumption as well as to styrene exposure, as measured by end‐of‐shift MA excretion. In opposition to data from rats, our results indicate that humans exposed to styrene excrete little styrene‐specific thioethers. The apparent inter‐individual variability in excretion of M1 and M2 suggests that they may not constitute suitable indicators of occupational styrene exposure.

The effect of the number of counted traverses on the estimation of the total spore count sampled on a non-cultivable slit impactor

Various counting rules are used for spore trap analysis. Partial count can lead to concentration errors. This paper demonstrates that the number of traverses counted affects the final results.

Systematic evaluation of the adsorption of organic vapors onto a miniaturized cartridge device using breakthrough tests in parallel experiment with a full size respirator cartridge

Breakthrough experiments are essential for the characterization of the adsorption capacity and micropore volume of activated carbon respiratory cartridges and for the validation and determination of cartridge service life models. In an effort to gain better control over environmental conditions in breakthrough tests and to obtain reliable data, a novel experimental approach using a miniaturized (Mini) cartridge was designed to replicate a small section of a respiratory cartridge. The Mini device and the organic vapor respiratory cartridge were tested in single and parallel experiments where in the former, one filter was tested one at a time and in the latter both devices were exposed simultaneously to the same conditions. The Mini device gave comparable results to the 10% breakthrough times and adsorption capacities of the organic vapor cartridges. The reproducibility of the packed carbon bed of the Mini provided strong support for using the Mini in breakthrough experiments for the characterization of the activated carbon adsorption capacity and estimation of cartridge service life.

Transesterification of Alkyl Acetates in Head Space Sampler

Abstract Environmental exposure of workers to organic solvents are routinely evaluated. Field samples are adsorbed on charcoal tubes and analysed by conventional GC or headspace (HS) GC. In the validation process of analytical protocols by HS-GC, it was observed that analysis of alkyl acetates yielded non-reproducible results when benzyl alcohol was used as desorbing solvent. Further studies by HS-GC with capillary column and GC-MS demonstrated a transesterification process of alkyl acetates. Reaction rate is dependent on steric hindrance of the acetate and on volatility of the newly formed alcohol. The presentation will describe some ways to obtain accurate and reproducible results. Data on environmental exposures of workers has been cumulated over two years in various industries involved in painting operations. Average worker exposure to aliphatic acetates will be discussed as well as other organic contaminants.