Exposure to volatile hydrocarbons and neurologic function among oil spill workers up to 6 years after the Deepwater Horizon disaster.

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.

Volatile Hydrocarbon Exposures and Incident Coronary Heart Disease Events: Up to Ten Years of Follow-up among Deepwater Horizon Oil Spill Workers.

BACKGROUND: During the 2010 Deepwater Horizon (DWH) disaster, response and cleanup workers were potentially exposed to toxic volatile components of crude oil. However, to our knowledge, no study has examined exposure to individual oil spill-related chemicals in relation to cardiovascular outcomes among oil spill workers. OBJECTIVES: Our aim was to investigate the association of several spill-related chemicals [benzene, toluene, ethylbenzene, xylene, n-hexane (BTEX-H)] and total hydrocarbons (THC) with incident coronary heart disease (CHD) events among workers enrolled in a prospective cohort. METHODS: Cumulative exposures to THC and BTEX-H across the cleanup period were estimated via a job-exposure matrix that linked air measurement data with self-reported DWH spill work histories. We ascertained CHD events following each worker's last day of cleanup work as the first self-reported physician-diagnosed myocardial infarction (MI) or a fatal CHD event. We estimated hazard ratios (HR) and 95% confidence intervals for the associations of exposure quintiles (Q) with risk of CHD. We applied inverse probability weights to account for bias due to confounding and loss to follow-up. We used quantile g-computation to assess the joint effect of the BTEX-H mixture. RESULTS: Among 22,655 workers with no previous MI diagnoses, 509 experienced an incident CHD event through December 2019. Workers in higher quintiles of each exposure agent had increased CHD risks in comparison with the referent group (Q1) of that agent, with the strongest associations observed in Q5 (range of HR=1.14-1.44). However, most associations were nonsignificant, and there was no evidence of exposure-response trends. We observed stronger associations among ever smokers, workers with ≤high school education, and workers with body mass index <30 kg/m2. No apparent positive association was observed for the BTEX-H mixture. CONCLUSIONS: Higher exposures to volatile components of crude oil were associated with modest increases in risk of CHD among oil spill workers, although we did not observe exposure-response trends. https://doi.org/10.1289/EHP11859.

Associations between airborne crude oil chemicals and symptom-based asthma.

RATIONALE: The 2010 Deepwater Horizon (DWH) oil spill response and cleanup (OSRC) workers were exposed to airborne total hydrocarbons (THC), benzene, toluene, ethylbenzene, o-, m-, and p-xylenes and n-hexane (BTEX-H) from crude oil and PM2.5 from burning/flaring oil and natural gas. Little is known about asthma risk among oil spill cleanup workers. OBJECTIVES: We assessed the relationship between asthma and several oil spill-related exposures including job classes, THC, individual BTEX-H chemicals, the BTEX-H mixture, and PM2.5 using data from the Gulf Long-Term Follow-up (GuLF) Study, a prospective cohort of 24,937 cleanup workers and 7,671 nonworkers following the DWH disaster. METHODS: Our analysis largely focused on the 19,018 workers without asthma before the spill who had complete exposure, outcome, and covariate information. We defined incident asthma 1-3 years following exposure using both self-reported wheeze and self-reported physician diagnosis of asthma. THC and BTEX-H were assigned to participants based on measurement data and work histories, while PM2.5 used modeled estimates. We used modified Poisson regression to estimate risk ratios (RR) and 95% confidence intervals (CIs) for associations between spill-related exposures and asthma and a quantile-based g-computation approach to explore the joint effect of the BTEX-H mixture on asthma risk. RESULTS: OSRC workers had greater asthma risk than nonworkers (RR: 1.60, 95% CI: 1.38, 1.85). Higher estimated THC exposure levels were associated with increased risk in an exposure-dependent manner (linear trend test p < 0.0001). Asthma risk also increased with increasing exposure to individual BTEX-H chemicals and the chemical mixture: A simultaneous quartile increase in the BTEX-H mixture was associated with an increased asthma risk of 1.45 (95% CI: 1.35,1.55). With fewer cases, associations were less apparent for physician-diagnosed asthma alone. CONCLUSIONS: THC and BTEX-H were associated with increased asthma risk defined using wheeze symptoms as well as a physician diagnosis.

Estimation of Airborne Vapor Concentrations of Oil Dispersants COREXIT™ EC9527A and EC9500A, Volatile Components Associated with the Deepwater Horizon Oil Spill Response and Clean-up Operations.

The Deepwater Horizon (DWH) drilling unit explosion above the Macondo oil well on 20 April 2010 caused the release of approximately 4.9 million barrels (779 million L) of oil into the Gulf of Mexico. As part of a larger spill response and clean-up effort, approximately 1.84 million gallons (6.81 million L) of chemical dispersants COREXIT™ EC9500A and COREXIT™ EC9527A were applied to the resultant oil slicks through spraying on the water surface by plane and by vessel and through injection at the release source near the seabed. The GuLF STUDY is investigating the health effects of workers involved in the oil spill response and clean-up after the DWH explosion, and estimates of possible exposure to chemical dispersants were needed. Exposures were estimated to the volatile components of COREXIT™ EC9500A [petroleum distillates, hydrotreated light, and propylene glycol (PG)] and of COREXIT™ EC9527A [2-butoxyethanol (2-BE) and PG] using two of AIHA IHMOD2.0© mathematical modeling tools along with the dispersants' chemical and physical properties. Monte Carlo simulations were used to reflect uncertainty in input parameters with both the two-box, constant emission model and the near and mid field plume model for indoor and outdoor activities, respectively. Possible exposure scenarios considered various evaporation rates, sizes of the dispersant pool, wind speeds, and ventilation rates. For the two-box model, mean near field exposure estimates to 2-BE ranged from 0.9 to 5.7 ppm, while mean far field estimated exposures ranged from 0.3 to 3.5 ppm. Estimates of mean near field plume model exposures ranged from 0.01 to 3.7 ppm at 2.5 ft from the source, and <0.01 to 0.3 ppm at 10 ft from the source. Estimated exposures to PG were approximately 10% of the calculated 2-BE exposures and exposures to petroleum distillates about 40% higher than the 2-BE estimates. Results indicate that compared with current occupational exposure guidelines, overexposure to petroleum distillates and PG probably did not occur in our study, but under some conditions, for short periods, exposure to 2-BE may have exceeded the limits for peak exposures. These estimates were developed for use in job-exposure matrices to estimate exposures of workers having contact with dispersant vapors for the GuLF STUDY.

Lung function in oil spill responders 4-6 years after the Deepwater Horizon disaster.

Oil spill response and clean-up (OSRC) workers were exposed to hazardous airborne chemicals following the 2010 Deepwater Horizon disaster. The aim of this study was to evaluate lung function in workers 4-6 years following the disaster using a prospective cohort. Participants who completed two spirometry test sessions 1-3 years, and 4-6 years after the spill (N = 1,838) were included and forced expiratory volume in 1 s (FEV1; ml), forced vital capacity (FVC; ml), and ratio (FEV1/FVC; %) determined. Linear mixed models were utilized to estimate relationships between OSRC exposures and lung function 4-6 years after the spill and changes since the prior measurement. Despite suggestive reduced lung function at 1-3 years, at the  4-6-year exam workers with total hydrocarbon (THC) exposure 1-2.99 ppm and ≥3 ppm compared to those with ≤0.29 ppm exhibited higher FEV1 (ß: 108 ml, 95% CI: 17, 198) and (ß: 118 ml, 95% CI: 5, 232), respectively. Compared with support workers, those in higher exposed jobs displayed greater improvement in FEV1 between visits: cleanup on water (ß: 143 ml, 95% CI: 35, 250), operations (ß: 132 ml, 95% CI: 30, 234) and response (ß: 149 ml, 95% CI: 43, 256). Greater FEV1 improvement was also associated with higher versus the lowest level THC exposure: 1-2.99 ppm (ß: 134 ml, 95% CI: 57, 210) and ≥3 ppm (ß: 205 ml, 95% CI: 109, 301). Lung function decrements seen shortly after the spill were no longer apparent 4-6 years later, with the greatest improvement among those with the highest exposures.

Dietary Supplementation in Children with Autism Spectrum Disorders: Common, Insufficient, and Excessive.

BACKGROUND: Little is known about the effect on dietary adequacy of supplements given to children with autism spectrum disorder (ASD). OBJECTIVE: This cross-sectional study examines dietary supplement use and micronutrient intake in children with ASD. DESIGN: Three-day diet/supplement records and use of a gluten/casein-free diet (GFCF) were documented. Estimates of usual intake of micronutrients from food and supplements were compared with the Dietary Reference Intakes. PARTICIPANTS: Children aged 2 to 11 years (N=288) with ASD from five Autism Treatment Network sites from 2009-2011. MAIN OUTCOME MEASURES: Percentage of children meeting or exceeding upper limits of micronutrient intake with or without supplements and relative to GFCF diet status. STATISTICAL ANALYSIS: Micronutrient intake from food and supplements was compared by Spearman rank correlation. Usual intake was estimated by the National Cancer Institute method adjusted for age, sex, supplement use, and GFCF diet. Adequacy of intake was compared between supplement use status and between food and total intake in supplement users relative to Dietary Reference Intakes limits. RESULTS: Dietary supplements, especially multivitamin/minerals, were used by 56% of children with ASD. The most common micronutrient deficits were not corrected (vitamin D, calcium, potassium, pantothenic acid, and choline) by supplements. Almost one-third of children remained deficient for vitamin D and up to 54% for calcium. Children receiving GFCF diets had similar micronutrient intake but were more likely to use supplements (78% vs 56%; P=0.01). Supplementation led to excess vitamin A, folate, and zinc intake across the sample, vitamin C, and copper among children aged 2 to 3 years, and manganese and copper for children aged 4 to 8 years. CONCLUSIONS: Few children with ASD need most of the micronutrients they are commonly given as supplements, which often leads to excess intake. Even when supplements are used, careful attention should be given to adequacy of vitamin D and calcium intake.