Breast cancer risk from pesticides may be missed if effects on mammary gland are not assessed in toxicology studies required for registration. Using US EPA's registration documents, we identified pesticides that cause mammary tumors or alter development, and evaluated how those findings were considered in risk assessment. Of 28 pesticides that produced mammary tumors, EPA's risk assessment acknowledges those tumors for nine and dismisses the remaining cases. For five pesticides that alter mammary gland development, the implications for lactation and cancer risk are not assessed. Many of the mammary-active pesticides activate pathways related to endocrine disruption: altering steroid synthesis in H295R cells, activating nuclear receptors, or affecting xenobiotic metabolizing enzymes. Clearer guidelines based on breast cancer biology would strengthen assessment of mammary gland effects, including sensitive histology and hormone measures. Potential cancer risks from several common pesticides should be re-evaluated, including: malathion, triclopyr, atrazine, propylene oxide, and 3-iodo-2-propynyl butylcarbamate (IPBC).

如果在注册所需的毒理学研究中未评估对乳腺的影响，则可能会忽略农药对乳腺癌的风险。使用美国环保署的注册文件，我们确定了导致乳腺肿瘤或改变发育的农药，并评估了在风险评估中如何考虑这些发现。在产生乳腺肿瘤的 28 种杀虫剂中，EPA 的风险评估确认了其中 9 种肿瘤，并驳回了其余病例。对于五种改变乳腺发育的杀虫剂，没有评估对哺乳期和癌症风险的影响。许多对乳腺有活性的杀虫剂会激活与内分泌干扰相关的途径：改变 H295R 细胞中的类固醇合成、激活核受体或影响外源性代谢酶。基于乳腺癌生物学的更清晰的指南将加强对乳腺影响的评估，包括敏感的组织学和激素测量。应重新评估几种常见农药的潜在癌症风险，包括：马拉硫磷、绿草定、阿特拉津、环氧丙烷和 3-iodo-2-propynyl butylcarbamate (IPBC)。