Exposure to persistent organic pollutants further increases risk of myocardial infarction in hypertensive populations

Purpose: Environmental exposure to persistent organic pollutants (POP) is an emerging risk factor for atherosclerosis-related cardiovascular diseases, including myocardial infarction (MI). Some studies also suggest that POP exposure increases the risk of hypertension, a well-established MI risk factor. A study of environmental exposure to POP and MI in hypertensive populations would clarify whether this exposure increases MI risk per se or if this effect is hypertension-dependent. Hypothesis: MI hospitalization rates would be higher in POP-exposed hypertensive populations than in unexposed hypertensive populations. Methods: We conducted an ecologic study of MI in POP-exposed and unexposed hypertensive populations. To examine the effect of POP exposure on MI hospitalization rates, we used the New York Statewide Planning and Research Cooperative System data on 92,772 hospital discharges for MI in 25-74 year-old hypertensive patients for a 12-year period (1993-2004). Residents of zip codes containing or abutting POP-contaminated sites were considered environmentally exposed. Relative risks were estimated by Poisson regression, adjusting for potential confounders. Results: MI hospitalization risk was 20.2% higher for POP-exposed hypertensive females compared to unexposed females (p<0.05); for males, a 5.8% increase was observed (p>0.05). Also, MI hospitalization risks were 64.8% higher for African Americans (p<0.05) and older age groups (compared to 25-34 year-olds, p<0.05); these findings, consistent with current knowledge of MI, prove the quality of our model. Conclusions: Environmental exposure to POP, per se, increases the risk of MI in hypertensive populations. Atherogenic effect of POP can be gender-modified due to gender differences in POP metabolism.