Kevin W. Hanley

Physical and chemical characterization of asphalt (bitumen) paving exposures.

The purpose of this research was to characterize the physical and chemical properties of asphalt (bitumen) fume and vapor in hot mix asphalt roadway paving operations. Area and personal air samples were taken using real-time equipment and extractive sampling and analytical methods to determine worker asphalt exposure, as well as to characterize the properties of the particulate and vapor phase components. Analysis of personal inhalation and dermal samples by gas chromatography/mass spectroscopy showed that the polycyclic aromatic hydrocarbon profile is dominated by compounds with molecular weights below 228, and that substituted and heterocyclic polycyclic aromatic hydrocarbons comprised approximately 71% of the detectable mass concentration (vapor and particulate combined). Principal components analysis shows that the polycyclic aromatic hydrocarbons with molecular weights greater than 190 are the driving force behind the polycyclic aromatic compound exposures measured for the dermal and particulate phases; there was no clear trend for the vapor phase Most of the aerosol particles are fine (mass median aerodynamic diameter 1.02 μ m; count median diameter 0.24 μ m).

Increased bladder cancer risk among workers exposed to o-toluidine and aniline: a reanalysis

Introduction In 1991, the US National Institute for Occupational Safety and Health (NIOSH) reported an increased bladder cancer risk in a cohort of 1749 workers potentially exposed to o-toluidine and aniline at a chemical manufacturing plant. As additional information showed that workers in certain departments had been misclassified regarding o-toluidine exposure, we therefore conducted a reanalysis of the data using updated exposure categories. Methods We updated exposure categories based on information ascertained during a plant walkthrough, documents on file at the plant, interviews with current and former employees, and answers provided by company and union officials to specific questions. Bladder cancer incidence was determined through 31 December 1988 and mortality through 31 December 1994. Results Thirteen cases of bladder cancer were observed versus 3.57 expected (New York State rates excluding New York City) (standardised incidence ratio (SIR) 3.64, 95% CI 1.94 to 6.23). Among workers classified as definitely exposed, increasing risks were observed for longer duration of employment (for ≥10 years, standardised rate ratio (SRR) 6.07, 95% CI 0.77 to 48.17) and time since first employment in the exposed departments (for ≥20 years, SRR 3.39, 95% CI 0.40 to 29.03). One bladder cancer death was observed among those definitely exposed. Conclusions These findings are comparable to the results reported earlier by NIOSH, and confirm that workers in this plant have an increased risk of bladder cancer.

Bladder cancer incidence among workers exposed to o-toluidine, aniline and nitrobenzene at a rubber chemical manufacturing plant

Background An earlier investigation found increased bladder cancer incidence among workers at a rubber chemical manufacturing plant that used o-toluidine, aniline and nitrobenzene. The cohort was expanded to include additional workers (n=1875) and updated through 2007 to assess bladder cancer with improved exposure characterisation. Methods Work histories were updated and exposure categories and ranks were developed for o-toluidine, aniline and nitrobenzene combined. Incident cancers were identified by linkage to six state cancer registries. Residency in time-dependent cancer registry catchment areas was determined. SIR and standardised rate ratios for bladder cancer were calculated by exposure category and cumulative rank quartiles for different lag periods. Cox regression was used to model bladder cancer incidence with estimated cumulative rank, adjusting for confounders. Indirect methods were used to control for smoking. Results Excess bladder cancer was observed compared to the New York State population (SIR=2.87, 95% CI 2.02 to 3.96), with higher elevations among workers definitely exposed (moderate/high) (SIR=3.90, 95% CI 2.57 to 5.68), and in the highest cumulative rank quartile (SIR=6.13, 95% CI 2.80 to 11.6, 10-year lag). Bladder cancer rates increased significantly with estimated cumulative rank (10-year lag). Smoking only accounted for an estimated 8% elevation in bladder cancer incidence. Conclusions Bladder cancer incidence remains elevated in this cohort and significantly associated with estimated cumulative exposure. Results are consistent with earlier findings in this and other cohorts. Despite other concurrent chemical exposures, we consider o-toluidine most likely responsible for the bladder cancer incidence elevation and recommend a re-examination of occupational exposure limits.

Exposure to o-Toluidine, Aniline, and Nitrobenzene in a Rubber Chemical Manufacturing Plant: A Retrospective Exposure Assessment Update

The National Institute for Occupational Safety and Health previously conducted a retrospective cancer incidence and mortality study of workers employed at a rubber chemical manufacturing plant. Compared with New York State incidence, the bladder cancer risk was 6.5 times higher for workers considered to have definite exposure to ortho-toluidine and aniline, and 4 times higher for workers with possible exposure. Exposure characterization in the original study utilized a surrogate measure based only on departments in which each worker was ever employed. As part of an update of that study, some departments in the three original exposure groups were reclassified based on a follow-up site visit; interviews with employees, management, and union representatives; and review of records including exposure data. An additional evaluation of department-job combinations, rather than only departments, was used to stratify exposure into four categories. An approximate rank of “relative” exposure level for each department-job-year combination was also assigned using a ranking scale of 0 to 10. The ranks were supported by quantitative exposure levels and by professional judgment. The numerical ranking scale was applied to each worker by multiplying the exposure rank by duration for each job held based on comprehensive individual work histories. The cumulative rank scores for this cohort ranged from 0 to 300 unit-years. The medians of the cumulative rank scores for the exposure categories showed very good agreement with increasing exposure classifications (e.g., 0.72, 4.6, 11, 14 unit-years for the four exposure categories). Workers’ breathing zone air sampling data collected at this plant from 1976–2004 were well below published occupational exposure limits for these chemicals, but additional cases of bladder cancer have been reported. The exposure assessment revisions and rank estimates will be used to analyze the updated bladder cancer incidence data.

Coronary artery disease and cancer mortality in a cohort of workers exposed to vinyl chloride, carbon disulfide, rotating shift work, and o‐toluidine at a chemical manufacturing plant

BACKGROUND We updated through 2007 the mortality experience of 1,874 workers employed at a New York State chemical manufacturing plant between 1946 and 2006. METHODS Reassessed exposures to vinyl chloride, carbon disulfide, and shift work and categories of o-toluidine exposure were based on year, department and job title. Standardized mortality ratios (SMR) compared mortality to that of the US population. Internal comparisons used directly standardized rate ratios. RESULTS Hepatobiliary cancer mortality was elevated among workers ever exposed to vinyl chloride (SMR = 3.80, 95% confidence interval 1.89-6.80); directly standardized rates increased with increasing vinyl chloride exposure duration. No increase in non-Hodgkin lymphoma mortality was observed with vinyl chloride and shift work exposures. Internal comparisons showed increased coronary artery disease mortality among long-term workers exposed to carbon disulfide and shift work for 4 years or more. CONCLUSIONS Excess coronary artery disease mortality confirms earlier results; further investigation is needed to understand risk factors.

Comparison and evaluation of urinary biomarkers for occupational exposure to spray adhesives containing 1-bromopropane

Three metabolites of 1-bromopropane (1-BP) were measured in urine samples collected from 30 workers exposed to 1-BP at two facilities making furniture seat cushions and evaluated for use as biomarkers of exposure. The mercapturic acid metabolite, N-acetyl-S-(n-propyl)-l-cysteine (AcPrCys), 3-bromopropionic acid (3-BPA), and bromide ion levels (Br−) were quantitated for this evaluation. The high exposure group consisted of 13 workers employed as adhesive sprayers who assembled foam cushions using 1-BP containing spray adhesives and the low exposure group consisted of 17 non-sprayers, who worked in various jobs without spraying adhesives. All workers’ urine voids were collected over the same 48 h period at work, and at home before bedtime, and upon awakening. Urinary AcPrCys and Br− levels were elevated in the sprayers compared to that of non-sprayers. Following HPLC-MS/MS analysis of mercapturic acid metabolite levels, 50 urine samples having the highest levels of AcPrCys were analyzed for 3-BPA. No 3-BPA was detected in any of the samples. The data collected from this study demonstrate that AcPrCys and Br− are effective biomarkers of 1-BP exposure, but 3-BPA is not.

Manganese Fractionation Using a Sequential Extraction Method to Evaluate Welders’ Shielded Metal Arc Welding Exposures During Construction Projects in Oil Refineries

The National Institute for Occupational Safety and Health has conducted an occupational exposure assessment study of manganese (Mn) in welding fume of construction workers rebuilding tanks, piping, and process equipment at two oil refineries. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. Seventy-two worker-days were monitored for either total or respirable Mn during stick welding and associated activities both within and outside of confined spaces. The samples were analyzed using an experimental method to separate different Mn fractions by valence states based on selective chemical solubility. The full-shift total particulate Mn time-weighted average (TWA) breathing zone concentrations ranged from 0.013–29 for soluble Mn in a mild ammonium acetate solution; from 0.26–250 for Mn0,2+ in acetic acid; from non-detectable (ND) – 350 for Mn3+,4+ in hydroxylamine-hydrochloride; and from ND – 39 micrograms per cubic meter (μg/m3) for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all Mn fractions in total particulate TWA ranged from 0.52–470 μg/m3. The range of respirable particulate Mn TWA concentrations were from 0.20–28 for soluble Mn; from 1.4–270 for Mn0,2+; from 0.49–150 for Mn3+,4+; from ND – 100 for insoluble Mn; and from 2.0–490 μg/m3 for Mn (sum of fractions). For all jobs combined, total particulate TWA GM concentrations of the Mn(sum) were 99 (GSD = 3.35) and 8.7 (GSD = 3.54) μg/m3 for workers inside and outside of confined spaces; respirable Mn also showed much higher levels for welders within confined spaces. Regardless of particle size and confined space work status, Mn0,2+ fraction was the most abundant followed by Mn3+,4+ fraction, typically >50% and ∼30–40% of Mn(sum), respectively. Eighteen welders’ exposures exceeded the ACGIH Threshold Limit Values for total Mn (100 μg/m3) and 25 exceeded the recently adopted respirable Mn TLV (20 μg/m3). This study shows that a welding fume exposure control and management program is warranted, especially for welding jobs in confined spaces.

Manganese speciation of laboratory-generated welding fumes

The objective of this laboratory study was to identify and measure manganese (Mn) fractions in chamber-generated welding fumes (WF) and to evaluate and compare the results from a sequential extraction procedure for Mn fractions with that of an acid digestion procedure for measurement of total, elemental Mn. To prepare Mn-containing particulate matter from representative welding processes, a welding system was operated in short circuit gas metal arc welding (GMAW) mode using both stainless steel (SS) and mild carbon steel (MCS) and also with flux cored arc welding (FCAW) and shielded metal arc welding (SMAW) using MCS. Generated WF samples were collected onto polycarbonate filters before homogenization, weighing and storage in scintillation vials. The extraction procedure consisted of four sequential steps to measure various Mn fractions based upon selective solubility: (1) soluble Mn dissolved in 0.01 M ammonium acetate; (2) Mn (0,II) dissolved in 25 % (v/v) acetic acid; (3) Mn (III,IV) dissolved in 0.5% (w/v) hydroxylamine hydrochloride in 25% (v/v) acetic acid; and (4) insoluble Mn extracted with concentrated hydrochloric and nitric acids. After sample treatment, the four fractions were analyzed for Mn by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). WF from GMAW and FCAW showed similar distributions of Mn species, with the largest concentrations of Mn detected in the Mn (0,II) and insoluble Mn fractions. On the other hand, the majority of the Mn content of SMAW fume was detected as Mn (III,IV). Although the concentration of Mn measured from summation of the four sequential steps was statistically significantly different from that measured from the hot block dissolution method for total Mn, the difference is small enough to be of no practical importance for industrial hygiene air samples, and either method may be used for Mn measurement. The sequential extraction method provides valuable information about the oxidation state of Mn in samples and allows for comparison to results from previous work and from total Mn dissolution methods.

0422 Coronary artery disease mortality among workers exposed to carbon disulfide and shift work at a chemical manufacturing plant

Objectives Previous studies at a New York State chemical manufacturing plant reported elevated risks of cardiovascular disease among workers. We updated the mortality experience of 1874 workers employed between 1949 and 2006 through December 31, 2007. We investigated exposures to carbon disulfide and shift work and their association with coronary artery disease. Method Jobs with carbon disulfide and shift work exposure (≥1 day) were identified among departments and job titles in specific years. Standardised mortality ratios (SMR) compared mortality to the US population, adjusted for gender, race, age, and calendar year. Internal comparisons used directly standardised rate ratios (SRR). Results Overall, excess deaths were observed for coroanary artery disease (SMR=1.24, 95% CI 1.04–1.48). Most workers exposed to carbon disulfide perfortmed shift work; we evaluated coronary artery disease mortality in groups defined by duration of exposure to these agents. Compared to the US population, statistically significant increases in mortality were observed among workers with both exposures for 90 days or more (SMR=1.36, 95% CI 1.03–1.76), and among workers with fewer than 90 days of both exposures (SMR=1.31, 95% CI 0.65–2.34). Using cutpoints of 4 years (median exposure duration among long-term cases), the results were no longer statistically significant. In internal comparisons, long-term workers exposed to carbon disulfide and shift work for 4 years or more had a near 3-fold increase in coronary artery disease mortality, compared to workers exposed less than 4 years. Conclusions Excess coronary artery disease mortality confirms earlier results, but further investigation is needed to understand risk factors.