Associations between serum levels of DDT compounds and cardiovascular disease death

Increasing evidence suggests persistent organic pollutants (POPs) are associated with cardiovascular disease (CVD). Studies have specifically examined the relationship between CVD risk factors and p,p'-DDE(1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene) the primary metabolite of the pesticide p,p'-DDT(1,1,1-trichloro-2,2-bis(pchlorophenyl)ethane) a once ubiquitous POP. Exposure possibly increases atherogenic serum lipid levels with resulting increased risk of CVD. Often DDE is used as a proxy for DDT because it is currently measurable. In the Child Health and Development Studies, a prospective pregnancy cohort, DDT is directly measurable from archived pregnancy serum taken during active use to allow examination of DDT exposure and subsequent risk of CVD.

Subjects were mothers with existing assays (N=1,740). Serum was drawn at mean age of 26 from 1959-1967 before DDT was banned. Measurable post-partum serum levels of DDT compounds (p,p'-DDT, p,p'-DDE and o,p-DDT(1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl)-ethane)) have been documented in this cohort. Forty-five cases of CVD death were identified by linkage to the California Vital Status files through 2008.

High DDT and low DDE levels were associated with more than a 3-fold increased risk of CVD death (Hazard Ratio (HR)=3.2; 95% Confidence Interval (CI)=1.01,10.06 for top DDT decile and HR= 4.9; CI=1.6,15.1 for lowest DDE decile). op-DDT was not associated. Effects were not explained by known CVD risk factors.

Findings support a possible role for DDT early in the disease process. DDE findings in this actively exposed cohort are consistent with slower metabolic conversion in women who died of CVD. Associations were only observable when all compounds were modeled together possibly explaining negative findings for previous studies.