Associations between airborne crude oil chemicals and symptom-based asthma
Kaitlyn G. Lawrence, Nicole M. Niehoff, Alexander P. Keil, William B. Jackson, Kate Christenbury, Patricia A. Stewart, Mark Stenzel, Tran Huynh, Caroline P. Groth, Gurumurthy Ramachandran, Sudipto Banerjee, Gregory C. Pratt, Matthew D. Curry, Lawrence S. Engel, Dale P. Sandler
Abstract
RATIONALE: from burning/flaring oil and natural gas. Little is known about asthma risk among oil spill cleanup workers. OBJECTIVES: 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: 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.