While there is compelling evidence of the association between occupational exposure to polycyclic aromatic hydrocarbons (PAHs) and risk of breast cancer (BC), findings on PAH dietary exposure are less consistent. The present study aims to evaluate the association between PAH dietary intake and BC risk. The study included 67,879 women who completed a validated semi-quantitative dietary questionnaire (208 food items) from the E3N-Generations cohort study. PAH dietary intake was estimated by combining E3N food consumption data with food contamination levels obtained from the second French total diet study (TDS2). Cox regression was used to estimate adjusted hazard ratios (HRs) and 95 % confidence intervals (CIs) for the association between PAH dietary intake (sum of four PAHs (PAH₄) namely benzo[a]pyrene (BaP), chrysene (CHR), benzo[a]anthracene (BaA) and benzo[b]fluoranthene (BbF)) and BC risk. Additionally, BaP, a surrogate for total PAHs, was investigated as the second exposure variable. After an average follow-up of 17.6 years, 5,686 incident BC were diagnosed. Overall, the estimated HRs for the associations between each quintile of PAH₄ and BC risk, taking the first quintile as reference, were all greater than 1, but were statistically significant only for the third quintile (HR_{Q3 vs Q1} = 1.10; CI: 1.01-1.20). By estrogen (ER) and progesterone (PR) hormone receptor status, we observed a positive association between PAH₄ dietary intake and ER-PR- BC (HR_{Q4 vs Q1} = 1.34; CI: 1.01-1.76). Moreover, there was a borderline positive association with BaP, for the second (HR_{Q2 vs Q1} = 1.08; CI: 0.99-1.17) and third (HR_{Q3 vs Q1} = 1.07; CI: 0.98-1.16) quintiles. This study supports a relationship between PAH₄ dietary intake and BC risk, notably with a non-linear trend. A positive but marginal association was observed between BaP dietary intake and BC risk.

Diet is a modifiable risk factor for non-communicable diseases which are the major causes of death worldwide. French dietary guidelines, updated in 2017, provide recommendations for a healthier diet. We aimed to study the association between adherence to these dietary guidelines and mortality in the E3N (Etude Epidémiologique auprès de femmes de l'Education Nationale) French cohort. A secondary objective was to investigate the role of dietary exposure to chemical contaminants in this association. We studied 72 585 women of the E3N prospective cohort, which completed a food frequency questionnaire in 1993. We estimated adherence to French dietary guidelines using the simplified “Programme National Nutrition Santé—guidelines score 2” (sPNNS-GS2, range -20.4 to 12.6). We estimated the association between sPNNS-GS2 and all-cause or cause-specific mortality using Cox proportional hazard models. Causes of death were coded and validated by the French Epidemiology Center on Medical Causes of Death (Inserm-CépiDc). During follow-up (1993–2014), we identified 6 441 deaths. The mean sPNNS-GS2 was 3.8 (SD 3.0). In the fully adjusted model, we found a non-linear association between sPNNS-GS2 and all-cause, all-cancer, breast cancer and lung cancer mortality (p-values for the overall association < 0.001), with a diminution of the risk as sPNNS-GS2 increases up to its median or 65th percentile (depending on the outcome), and then a plateau (for all-cause and breast cancer mortality) or an inversion of the trend (for all-cancer and lung cancer mortality). Furthermore, we identified a linear inverse association with cardiovascular diseases mortality (HRoneSTD [95%CI]: 0.86 [0.76; 0.97]), and no association with colorectal cancer mortality. We observed similar results when additionally adjusting on dietary exposure to chemical contaminants. This study conducted in a large prospective cohort following more than 70 000 women for over 20 years suggested that higher adherence to French dietary guidelines was associated with a reduced risk of mortality from all-cause, cardiovascular diseases, all-cancer, breast cancer, and lung cancer, except for high values of adherence for lung cancer mortality. These results contribute to informing on the importance of following the French nutritional recommendations.