BACKGROUND:During the 2010 Deepwater Horizon (DWH) disaster, oil spill response and cleanup (OSRC) workers were exposed to toxic volatile components of crude oil. Few studies have examined exposure to individual volatile hydrocarbon chemicals below occupational exposure limits in relation to neurologic function among OSRC workers. OBJECTIVES:To investigate the association of several spill-related chemicals (benzene, toluene, ethylbenzene, xylene, n-hexane, i.e., BTEX-H) and total petroleum hydrocarbons (THC) with neurologic function among DWH spill workers enrolled in the Gulf Long-term Follow-up Study. METHODS:Cumulative exposure to THC and BTEX-H across the oil spill cleanup period were estimated using a job-exposure matrix that linked air measurement data to detailed self-reported DWH OSRC work histories. We ascertained quantitative neurologic function data via a comprehensive test battery at a clinical examination that occurred 4-6 years after the DWH disaster. We used multivariable linear regression and modified Poisson regression to evaluate relationships of exposures (quartiles (Q)) with 4 neurologic function measures. We examined modification of the associations by age at enrollment (<50 vs. ≥50 years). RESULTS:We did not find evidence of adverse neurologic effects from crude oil exposures among the overall study population. However, among workers ≥50 years of age, several individual chemical exposures were associated with poorer vibrotactile acuity of the great toe, with statistically significant effects observed in Q3 or Q4 of exposures (range of log mean difference in Q4 across exposures: 0.13-0.26 μm). We also observed suggestive adverse associations among those ≥ age 50 years for tests of postural stability and single-leg stance, although most effect estimates did not reach thresholds of statistical significance (p < 0.05). CONCLUSIONS:Higher exposures to volatile components of crude oil were associated with modest deficits in neurologic function among OSRC workers who were age 50 years or older at study enrollment.

Background Burning/flaring of oil/gas during the Deepwater Horizon oil spill response and cleanup (OSRC) generated high concentrations of fine particulate matter (PM 2.5 ). Personnel working on the water during these activities may have inhaled combustion products. Neurologic effects of PM 2.5 have been reported previously but few studies have examined lasting effects following disaster exposures. The association of brief, high exposures and adverse effects on sensory and motor nerve function in the years following exposure have not been examined for OSRC workers. Objectives We assessed the relationship between exposure to burning/flaring-related PM 2.5 and measures of sensory and motor nerve function among OSRC workers. Methods PM 2.5 concentrations were estimated from Gaussian plume dispersion models and linked to self-reported work histories. Quantitative measures of sensory and motor nerve function were obtained 4–6 years after the disaster during a clinical exam restricted to those living close to two clinics in Mobile, AL or New Orleans, LA ( n = 3401). We obtained covariate data from a baseline enrollment survey and a home visit, both in 2011–2013. The analytic sample included 1186 participants. Results We did not find strong evidence of associations between exposure to PM 2.5 and sensory or motor nerve function, although there was a suggestion of impairment based on single leg stance among individuals with high exposure to PM 2.5 . Results were generally consistent whether we examined average or cumulative maximum exposures or removed individuals with the highest crude oil exposures to account for co-pollutant confounding. There was no evidence of exposure-response trends. Impact statement Remediating environmental disasters is essential for long-term human and environmental health. During the Deepwater Horizon oil spill disaster, burning and flaring of oil and gas were used to remove these pollutants from the environment, but led to potentially high fine particulate matter exposures for spill response workers working on the water. We investigate the potential adverse effects of these exposures on peripheral nerve function; understanding the potential health harm of remediation tactics is necessary to inform future clean up approaches and protect human health.

This chapter introduces the medical specialty called occupational and environmental medicine, its goals and methods. This chapter presents information that: defines, categorizes, and quantifies occupational and environmental diseases; describes the professions that work in occupational health care; describes the activities of occupational health care, including diagnosis and treatment, screening and surveillance, evaluation for attribution, and training and education; describes the settings in which occupational and environmental medicine is practiced; and introduces ethical issues that arise in delivering occupational and environmental health care.

Teichman, Ron MD, MPH; Cassidy, Susan O. MD, JD; Brandt-Rauf, Paul MD; Cannella, Joseph MD; Gresch, Elizabeth MD; Goldberg, Robert MD; McCunney, Robert MD; Rischitelli, D Gary MD; Wester, Mary Sue MD; Zanick, David C. MD Author Information

This case report describes behavioral and neuropsychological function in a young man who experienced chronic exposure to elemental mercury at home from age 4 through 9 years. Data are presented on school history, behavior, and performance on standardized tests during the developmental period, and from a full neuropsychological evaluation at age 19 years, several years after environmental exposure had ended. These data specify the course of a decline in function as development proceeds. The patient's progress appeared normal in the preschool period but pronounced academic difficulties and persistent emotional irritability emerged during the elementary school years. At age 19 years, neurophysiological testing revealed diminished executive function, difficulties with language, problems with visuospatial orientation, deficiencies in fine motor control. and manual tremor. Tension, irritability, and depressive affect were evident as well as marked problems with academic performance. These findings suggest widespread cerebral dysfunction, both cortical and subcortical, and are consistent with the diffuse pattern of brain damage seen in children with exposure to heavy metals.

Because of its favorable side effects profile, the oral chelating agent dimercaptosuccinic acid is often used for treatment of lead intoxication. We report a case of a 45-year-old black male with glucose-6-phosphate dehydrogenase deficiency and a 17 year history of occupational lead exposure who developed hemolysis during treatment with dimercaptosuccinic acid for symptomatic lead intoxication.

Six specific issues affecting the progressive modification of neurobehavioral test batteries used in field studies of populations exposed to neurotoxicants are discussed and test review recommendations are provided addressing each issue. The issues include: (a) general test review standards, (b) comprehensive assessment, (c) tailored batteries, (d) incorporation of new tests and techniques, (e) personnel and mechanisms for review, and (f) development of a battery assessing peripheral nervous system function.

Measurement of vibrotactile threshold (VT) has been proposed as a rapid, nonaversive method of assessing the functional integrity of large myelinated peripheral nerve fibers. Current methods of assessing peripheral nerve function include physical examination and electrophysiologic evaluation. Physical examination is of unknown reliability and results in categorical outcomes. Electrodiagnostic procedures are sensitive and yield quantitative results, however, their aversive nature may discourage voluntary participation in epidemiologic studies. In order to justify the substitution of VT measurement for nerve conduction study in field investigations of neurologic dysfunction, we have initialed a comprehensive evaluation of methods suitable for such applications. The elements of this program include (1) comparison of psychophysical procedures, (2) determination of threshold reliability, (3) comparison of VT with electrophysiologic evaluation and physical examination, (4) development of age- and height-standardized nonnative values, and (5) measurement of VTs in groups at risk of peripheral nerve dysfunction. Group studies include workers exposed to mercury, solvents, industrial chemicals, and hand-arm vibration. The utility of VT measurement in occupational neuroepidemiology will be discussed.