Linking dietary-derived arsenic exposure to blood serum arsenic burden, potential food sources, and breast cancer risk in the EPIC-Heidelberg cohort

Abstract Purpose Breast cancer is the most common cancer among women worldwide, yet the role of environmental toxicants remains unclear. Arsenic is an International Agency for Research on Cancer classified carcinogen linked to skin, lung, and bladder cancers. The relationship between dietary arsenic intake levels and blood arsenic concentrations, particularly across sexes, and the association between dietary arsenic intake and breast cancer remain understudied. This study aimed to address these gaps. Methods Measurements of arsenic in foods collected from 1995 to 2022 in the German monitoring programme were used to estimate long-term dietary intake. Serum arsenic levels were measured using inductively coupled plasma mass spectrometry. Participants were aged 35–65 years; 2,674 non-cases were included in the arsenic intake-serum arsenic analysis, and 631 incident cases and 1,708 non-cases in the breast cancer analysis. Partial spearman’s rank correlation and logistic regression models assessed the association between dietary arsenic intake and serum arsenic levels. Prentice-weighted Cox proportional hazards models with age as underlying time scale were used to assess associations between dietary arsenic intake and breast cancer risk. Results No association was observed between total or estimated inorganic arsenic intake and breast cancer risk (HR 1.1, 95% CI: 0.93–1.31; HR 0.9, 95% CI: 0.76–1.07), including in subgroup analyses by menopausal status (pre- and post-menopausal), estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status. Weak positive correlations were observed between total and estimated inorganic arsenic intake and serum arsenic concentrations (ρ = 0.20 and ρ = 0.07). However, regression analyses showed that total arsenic intake was associated with serum arsenic in both sexes (men: OR 3.48, 95% CI 2.33–5.22; women: OR 2.60, 95% CI 1.84–3.68), whereas estimated inorganic arsenic intake were associated only among women in the second and fourth quintiles (OR 1.53 [95% CI 1.10–2.14] and 1.90 [1.33–2.73], respectively). Conclusion Dietary arsenic intake was not significantly associated with serum arsenic levels or incident breast cancer.