Evaluation and comparison of three exposure assessment techniques

This study was conducted to verify the performance of a recently developed subjective rating (SR) exposure assessment technique and to compare estimates made using this and two other techniques (trade mean, or TM, and task-based, or TB, approaches) to measured exposures. Subjects (n = 68) each completed three full-shift noise measurements over 4 months. Individual measured mean exposures were created by averaging each subject's repeated measurements, and TM, TB, and SR estimates were created using noise levels from worksites external to the current study. The bias, precision, accuracy, and absolute agreement of estimates created using the three techniques were evaluated by comparing estimated exposures with measured exposures. Trade mean estimates showed little bias, while neither the TM nor the SR techniques produced unbiased estimates, and the SR estimates showed the greatest bias of the three techniques. Accuracy was essentially equivalent among the three techniques. All three techniques showed poor agreement with measured exposures and were not highly correlated with each other. Estimates from the SR technique generally performed similarly to the TM and TB techniques. Methods to incorporate information from each technique into exposure estimates should be explored.

Noise exposure and hearing loss prevention programmes after 20 years of regulations in the United States

OBJECTIVES

To evaluate noise exposures and hearing loss prevention efforts in industries with relatively high rates of workers' compensation claims for hearing loss.

METHODS

Washington State workers' compensation records were used to identify up to 10 companies in each of eight industries. Each company (n = 76) was evaluated by a management interview, employee personal noise dosimetry (n = 983), and employee interviews (n = 1557).

RESULTS

Full-shift average exposures were > or =85 dBA for 50% of monitored employees, using Occupational Safety and Health Administration (OSHA) parameters with a 5 dB exchange rate (L(ave)), but 74% were > or =85 dBA using a 3 dB exchange rate (L(eq)). Only 14% had L(ave) > or =90 dBA, but 42% had L(eq) > or =90 dBA. Most companies conducted noise measurements, but most kept no records, and consideration of noise controls was low in all industries. Hearing loss prevention programmes were commonly incomplete. Management interview scores (higher score = more complete programme) showed significant associations with percentage of employees having L(ave) > or =85 dBA and presence of a union (multiple linear regression; R2 = 0.24). Overall, 62% of interviewed employees reported always using hearing protection when exposed. Protector use showed significant associations with percentage of employees specifically required to use protection, management score, and average employee time spent > or =95 dBA (R2 = 0.65).

CONCLUSIONS

The findings raise serious concerns about the adequacy of prevention, regulation, and enforcement strategies in the United States. The percentage of workers with excessive exposure was 1.5-3 times higher using a 3 dB exchange rate instead of the OSHA specified 5 dB exchange rate. Most companies gave limited or no attention to noise controls and relied primarily on hearing protection to prevent hearing loss; yet 38% of employees did not use protectors routinely. Protector use was highest when hearing loss prevention programmes were most complete, indicating that under-use of protection was, in some substantial part, attributable to incomplete or inadequate company efforts.

Hospital preparedness for victims of chemical or biological terrorism

OBJECTIVES

This study examined hospital preparedness for incidents involving chemical or biological weapons.

METHODS

By using a questionnaire survey of 224 hospital emergency departments in 4 northwestern states, we examined administrative plans, training, physical resources, and representative medication inventories.

RESULTS

Responses were received from 186 emergency departments (83%). Fewer than 20% of respondent hospitals had plans for biological or chemical weapons incidents. About half (45%) had an indoor or outdoor decontamination unit with isolated ventilation, shower, and water containment systems, but only 12% had 1 or more self-contained breathing apparatuses or supplied air-line respirators. Only 6% had the minimum recommended physical resources for a hypothetical sarin incident. Of the hospitals providing quantitative answers about medication inventories, 64% reported sufficient ciprofloxacin or doxycycline for 50 hypothetical anthrax victims, and only 29% reported sufficient atropine for 50 hypothetical sarin victims (none had enough pralidoxime).

CONCLUSIONS

Hospital emergency departments generally are not prepared in an organized fashion to treat victims of chemical or biological terrorism. The planned federal efforts to improve domestic preparedness will require substantial additional resources at the local level to be truly effective.

Neuropsychological function in retired workers with previous long-term occupational exposure to solvents

OBJECTIVES

It is plausible that neurodegenerative processes of aging might have a contributing role in the development of chronic effects of exposure to organic solvents. This study evaluated the risk for neuropsychological deficits among retired workers, relative to their histories of exposure to occupational solvents.

METHODS

This cross sectional study evaluated retired male workers, 62-74 years of age, including 89 people with previous long-term occupational exposure to solvents (67 retired painters and 22 retired aerospace manufacturing workers), and 126 retired carpenters with relatively minimal previous exposure to solvents. Subjects completed a standardised neuropsychological evaluation and psychiatric interview, structured interviews for histories of occupational exposure and alcohol consumption, and questionnaires assessing neurological and depressive symptoms.

RESULTS

By comparison with the carpenters, the painters on average reported greater cumulative alcohol consumption and had lower scores on the WAIS-R vocabulary subtest, usually presumed to reflect premorbid intellectual functioning. These findings, however, were not sufficient to account for the other study findings. Controlling for age, education, vocabulary score, and alcohol use, the painters had lower mean scores on test measures of motor, memory, and reasoning ability; and a subgroup of aerospace workers with moderate to high cumulative exposure to solvents (n = 8) had lower mean scores on measures of visuomotor speed, and motor, attention, memory, and reasoning ability. Subjects were more likely to have an increased number of relatively abnormal test scores (three or more outlier scores on 17 test measures) among both the painter group (odds ratio (OR), 3.1; 95% confidence interval (95% CI) 1.5 to 6.2) and the subgroup of aerospace workers with higher cumulative exposure (OR 5.6; 95% CI 1.0 to 38). The painters, but not the aerospace workers, reported significantly more neurological and depressive symptoms.

CONCLUSIONS

The findings are consistent with residual central nervous system dysfunction from long-term exposure to organic solvents, persisting years after the end of exposure.

Longitudinal decline in measured firefighter single-breath diffusing capacity of carbon monoxide values. A respiratory surveillance dilemma

Seattle firefighters participate in a voluntary annual medical surveillance program including measurements of ventilatory capacity (FVC and FEV1) and single-breath diffusing capacity of carbon monoxide (DLCO). From 1989 to 1996, average % predicted DLCO (Crapo) for all participating firefighters declined from 94.4% (95% confidence interval [CI]: 93.4% to 95.5%) to 87.3% (95% CI: 86.2% to 88.3%), with no significant change in average FVC or FEV1. A random-effects regression model based on data from 812 firefighters with at least two annual sets of DLCO measurements showed the expected associations between DLCO and age, height, gender, race, ventilatory capacity, and smoking. In addition, two important temporal changes were observed, including, for an average firefighter, a large mean decline in DLCO of -1.02 ml/min/mm Hg associated with year of measurement, and a relatively smaller decline of -0.006 ml/min/mm Hg associated with number of fires fought. Although the stability of ventilatory capacity over time is reassuring, the marked temporal decline in diffusing capacity among this population of firefighters raises issues of concern. Interpretation of the observed decline poses a dilemma in terms of the reliability and efficacy of diffusing capacity as a screening tool, in whether DLCO is subject to unacceptable technical variability or whether it might provide more sensitive detection of early adverse respiratory effects of smoke inhalation.

Occupational hearing loss in Washington state, 1984-1991: I. Statewide and industry-specific incidence

This study examined non-federal workers' compensation claims accepted for hearing-related conditions in Washington state during 1984-1991. Seventy percent of 6,539 filed claims were accepted (n = 4,547); most accepted claims resulted in disability compensation (n = 3,660; 80%). A transient 50-fold increase in claims from one worksite accounted for one-third of all hearing-related claims in the state for 2 years. The number and incidence of accepted claims from all other worksites increased significantly across the study period. The incidence was 0.3 per 10(3) workers per year, overall, but was at least five-fold higher in industries that accounted for half of accepted claims, and reached 38- to 71-fold higher in some industries. This study indicates: 1) workers' compensation claims under-estimate the true frequency of occupational illness, representing only the "tip of the iceberg;" 2) hearing loss is a growing problem in occupational health; and 3) workers' compensation data are potentially useful to identify specific high-incidence industries for possible interventions.

Occupational hearing loss in Washington state, 1984-1991: II. Morbidity and associated costs

This study examined 4,547 workers' compensation claims accepted for hearing-related conditions in Washington state between 1984 and 1991; 80% resulted in disability compensation (n = 3,660). Acute hearing-related conditions comprised 11% of accepted conditions (95% confidence interval [CI], 2-15%); most claims were for chronic noise-related hearing loss. Tinnitus was reported in 64% of accepted claims (95% CI, 54-75%). The median binaural-equivalent hearing loss in compensated claims was 12.5% (inter-quartile interval, 5-22%; 90th percentile, 34%), although it declined by 30% during the study period. The number of claims and associated impairment increased with claimant age, but the number of claims dropped dramatically after age 65. Annual total disability settlements almost tripled in 8 years, totaling $22.8 million. This study indicates that occupational hearing-related conditions: 1) are manifested by mild to moderate hearing loss, accompanied by tinnitus in a majority of cases; 2) may be under-recognized in older, formerly noise-exposed individuals; and 3) were associated with substantial increases in compensation and medical costs over time, through 1991.

Environmental chemical exposures and disturbances of heme synthesis

Porphyrias are relatively uncommon inherited or acquired disorders in which clinical manifestations are attributable to a disturbance of heme synthesis (porphyrin metabolism), usually in association with endogenous or exogenous stressors. Porphyrias are characterized by elevations of heme precursors in blood, urine, and/or stool. A number of chemicals, particularly metals and halogenated hydrocarbons, induce disturbances of heme synthesis in experimental animals. Certain chemicals have also been linked to porphyria or porphyrinuria in humans, generally involving chronic industrial exposures or environmental exposures much higher than those usually encountered. A noteworthy example is the Turkish epidemic of porphyria cutanea tarda produced by accidental ingestion of wheat treated with the fungicide hexachlorobenzene. Measurements of excreted heme precursors have the potential to serve as biological markers for harmful but preclinical effects of certain chemical exposures; this potential warrants further research and applied field studies. It has been hypothesized that several otherwise unexplained chemical-associated illnesses, such as multiple chemical sensitivity syndrome, may represent mild chronic cases of porphyria or other acquired abnormalities in heme synthesis. This review concludes that, although it is reasonable to consider such hypotheses, there is currently no convincing evidence that these illnesses are mediated by a disturbance of heme synthesis; it is premature or unfounded to base clinical management on such explanations unless laboratory data are diagnostic for porphyria. This review discusses the limitations of laboratory measures of heme synthesis, and diagnostic guidelines are provided to assist in evaluating the symptomatic individual suspected of having a porphyria.

Organophosphate pesticide exposure in a group of Washington State orchard applicators

As part of a study to investigate the potential for organophosphates to cause chronic neurologic sequelae, we assessed the pesticide exposure experience of a group of Washington State apple orchard applicators. Seasonal monitoring of cholinesterase activity for 48 regular organophosphate applicators and a control group of 40 slaughterhouse workers was performed. A subset of the pesticide applicators participated in an in-depth exposure assessment. This involved observation of spraying activities during 1 spray day, as well as cholinesterase monitoring and dermal exposure assessment using a fluorescent tracer in the pesticide formulation. Comparison of seasonal red blood cell cholinesterase change in pesticide workers according to exposure level, characterized by frequency of pesticide spraying and protective equipment use, showed lower cholinesterase levels among higher exposed groups compared to lesser exposed groups. In-depth exposure assessment revealed exposure primarily on the head and hand regions. Subclinical changes (less than 15% inhibition) in red cell cholinesterase correlated well with dermal exposure calculations. This study suggests that cholinesterase monitoring may be a useful biological marker for even subclinical organophosphate pesticide effects.

Peripheral markers of neurochemical function among workers exposed to styrene

A cross sectional study of biological markers of neurochemical function in peripheral blood cells, and self reported nervous system symptoms, was conducted among 60 workers exposed to styrene in three reinforced plastics plants and 18 reference workers not exposed to styrene or other solvents. Concentrations of styrene in the air at the plants ranged from less than 1 to 160 ppm. Biomarkers of neurochemical function measured were: sigma receptor binding in lymphocytes, monoamine oxidase type B (MAO-B) activity in platelets, and serotonin uptake by platelets. Blood styrene concentration was used as the exposure index to take account of the use of protective equipment and dermal uptake. Four blood styrene exposure groups were defined as: non-exposed (reference) and exposed to less than 0.05, 0.05-0.19, and greater than or equal to 0.20 micrograms/ml. The prevalences of headache, dizziness, light headedness, fatigue, irritability, memory loss, and feeling "drunk" at work increased with increasing blood styrene concentration. No effect on sigma receptor binding was seen. A slight positive correlation was found for uptake of serotonin, which has been used as an exposure related effect indicator in previous studies of workers exposed to solvents. The MAO-B activity decreased with increasing blood styrene concentration; the mean (SE) MAO-B values for the four groups were 34.2 (3.0), 28.1 (5.3), 20.1 (4.8), and 16.9 (7.7) pmol/10(7) cells/min. The MAO-B activity also correlated negatively with the number of reported nervous system symptoms, whereas no associations were seen between prevalence of symptoms and either serotonin uptake or sigma receptor binding. The findings for MAO-B activity are consistent with previously reported experimental data, and suggest that MAO-B may be a useful marker of styrene neurotoxicity.

Cobalt exposure in a carbide tip grinding process

Reports relating hard metal disease or nonspecific respiratory symptoms to tungsten or cobalt exposure have been published in the past 20 yr. This report discusses a work site investigation of a small company, employing approximately 50 workers, producing carbide tip saw blades for the woodworking industry. Cobalt exposure was characterized by ambient air monitoring (area and personnel), particle size determination, and biological monitoring. Area sampling for cadmium, cobalt, and tungsten indicated low ambient air levels in all manufacturing areas except the grinding department, which had cobalt air levels approaching the threshold limit value of 0.05 mg/m3. Area airborne cobalt exposure levels measured over six shifts in the grinding department ranged from 0.017 to 0.12 mg/m3 for the total collection method and 0.002 to 0.028 mg/m3 for the method collecting respirable particles. Cobalt content in the total and respirable fractions was similar. Urine monitoring indicated production workers have elevated cobalt levels, and the grinders' levels were higher than other production workers. The grinding coolant was found to have elevated cobalt concentrations. A survey of coolants from nine carbide grinding shops indicated the elevated cobalt concentrations may be common.

Chronic central nervous system effects of acute organophosphate pesticide intoxication. The Pesticide Health Effects Study Group

Acute organophosphate pesticide poisonings cause substantial morbidity and mortality world wide; however, whether organophosphates cause chronic neurological sequelae has not been established. To see whether single episodes of acute unintentional organophosphate intoxication lead to chronic neuropsychological dysfunction, we carried out a retrospective study of agricultural workers in Nicaragua who had been admitted to hospital between July 1, 1986, and July 31, 1988, for occupationally related organophosphate intoxication. This "poisoned" group (36 men) was tested on average about two years after the episode of pesticide poisoning and compared with a matched control group. The poisoned group did much worse than the control group on all neuropsychological subtests, with significantly worse performance on five of six subtests of a World Health Organisation neuropsychological test battery and on 3 of 6 additional tests that assessed verbal and visual attention, visual memory, visuomotor speed, sequencing and problem solving, and motor steadiness and dexterity. Differences in neuropsychological performance could not be explained by other factors. The findings of a persistent decrease in neuropsychological performance among individuals with previous intoxication emphasise the importance of prevention of even single episodes of organophosphate poisoning.

Psychosis following styrene exposure: a case report of neuropsychological sequelae

A patient with a significant history of substance abuse was exposed to styrene and other solvents in the workplace. He became acutely psychotic, experiencing visual hallucinations. The psychosis was controlled with neuroleptic medications and avoidance of solvent exposure, but he continued to show significant deficits in visual-spatial and memory abilities. These deficits cleared with time away from the workplace. The case is of interest in terms of neuropsychological sequelae of solvent exposure and potential interaction of solvents with alcohol and recreational drugs.

Pregnancy outcomes among female flight attendants

Flight attendants have been reported to be at increased risk for menstrual abnormalities and for spontaneous fetal loss. This study examined Washington State birth certificates for associations between adverse pregnancy outcomes and maternal employment as a flight attendant. Current pregnancy outcomes (low birthweight, prematurity, low Apgar scores, and abnormal sex ratio) were not significantly related to occupation. Flight attendants reported their preceding pregnancy resulted in a spontaneous fetal loss nearly twice as often as other women (relative risk = 1.9, 95% confidence interval = 1.3-2.7). However, when comparison was restricted to other employed women, the risk was lower (RR = 1.3, 95% CI = 0.9-1.9). A clinically significant pregnancy risk among flight attendants cannot be excluded on the basis of this study, but the apparent excess risk of spontaneous fetal loss in this and particularly in a previous study could be explained at least in part by methodologic limitations.

Occupational solvent exposure and glomerulonephritis. A case report and review of the literature

We describe a patient who presented with renal failure after a one-year period of unprotected heavy occupational exposure to organic solvents. Renal biopsy results and serological findings were diagnostic of anti-glomerular basement membrane antibody-mediated glomerulonephritis. An analytic review of the literature revealed substantial evidence linking solvent exposure to the development of glomerulonephritis (GN), with seven of nine case-control studies demonstrating a statistically significant association. Odds ratios were reported by or could be calculated for six of these studies, and the five positive studies detected a 2.8- to 8.9-fold increased risk for GN among solvent-exposed individuals. The findings in several of these studies of dose-response relationships, the reports of variations in disease severity in relation to exposure intensity, and the absence of alternative explanations for the association provide additional supportive evidence for a solvent effect. In the majority of cases of anti-glomerular basement membrane antibody-mediated GN and other types of GN, there is no remarkable preceding exposure to organic solvents. However, we conclude that in the case presented herein and in cases of GN with similar exposure histories, solvent exposure may play a significant contributing role in the development of GN.

Paternal employment in solvent related occupations and adverse pregnancy outcomes

Washington State birth certificates were examined for associations between adverse pregnancy outcomes and paternal employment in solvent exposed occupations. Four cohorts defined by live, singleton births to fathers usually employed as auto body shop workers, painters (construction and maintenance), printers, or fibreglass workers were compared retrospectively with both a systematically selected control cohort and a low solvent exposed, occupationally defined control cohort (paternal electricians). The effects of maternal race and medical illness were controlled by sample restriction; maternal age and gravidity by stratified analysis. There was evidence of increased risk of low birth weight for infants born to fathers employed as body shop workers (relative risk = 1.6; 95% confidence interval = 1.1-2.4) or painters (RR = 1.4; CI = 0.9-2.1) when compared with the systematically selected controls but not with the electrician controls. The excess risk appeared stronger when only term infants were analysed suggesting a mechanism of growth retardation rather than prematurity. There was no evidence of increased risk among the other exposed cohorts or for other adverse pregnancy outcomes. Several design features limit the interpretation of the findings and confirmation by other studies is needed.