Exposure to
endocrine-disrupting chemicals, like
Polybrominated diphenyl ethers (
PBDEs), is suspected of playing a role in the occurrence of
breast cancer. Moreover, there is growing evidence that food chemical contaminants, especially lipophilic ones such as
PBDEs, could interact with different components of the diet. The objective of the present study was to assess the association between dietary intake of
PBDEs and
breast cancer risk in the French E3N cohort study, and to investigate the potential modification of this association by
vegetable oil consumption. The study included 67879 women. Intakes of eight
PBDEs were estimated using food consumption data from a validated semi-quantitative food frequency questionnaire, and food contamination levels measured by the French Agency for Food, Environmental and Occupational Health and Safety (ANSES). Cox proportional hazards models were used to estimate Hazard Ratios (HR) and 95% Confidence Intervals (CI) for the association between total
PBDEs dietary intake and
breast cancer risk. Interaction measures for
vegetable oil consumption were estimated on both additive and multiplicative scales. The women were followed for a maximum of 21.4 years, and 5 686 developed an incident
breast cancer. A positive linear trend was highlighted between dietary intake of
PBDEs in quintile groups and
breast cancer risk, borderline with statistical significance (p-trend = 0.06, HRQ5vsQ1 and 95% CI: 1.09 [0.99;1.20]). Interaction measures for
vegetable oil consumption were significant in both additive and multiplicative scales. Higher effect sizes of the association were highlighted in high consumers of
vegetable oil, i.e. ≥4.6 g/day (HRQ5vsQ1 and 95% CI: 1.23 [1.08; 1.40]), and almost no effect were found in low consumers (HRQ5vsQ1 and 95% CI: 0.97 [0.86; 1.10]). Highlighting such interactions between nutrients and chemicals is crucial to develop efficient dietary recommendations to limit the negative health effects associated with exposure to food chemical contaminants.