BACKGROUND The prevalence of toxic chemicals in US commerce has prompted some states to adopt laws to reduce exposure. One with broad reach is California's Proposition 65 (Prop 65), which established a list of chemicals that cause cancer, developmental harm, or reproductive toxicity. The law is intended to discourage businesses from using these chemicals and to minimize consumer exposure. However, a key question remains unanswered: Has Prop 65 reduced population-level exposure to the listed chemicals? OBJECTIVE We used national biomonitoring data from the Centers for Disease Control and Prevention (CDC) to evaluate the impact of Prop 65 on population-level exposures. METHODS We evaluated changes in blood and urine concentrations of 37 chemicals (including phthalates, phenols, VOCs, metals, PAHs, and PFAS), among US National Health and Nutrition Examination Survey (NHANES) participants in relation to the time of chemicals' Prop 65 listing. Of these, 11 were listed prior to, 11 during, and 4 after the biomonitoring period. The remaining 11 were not listed but were closely related to a Prop 65-listed chemical. Where biomonitoring data were available from before and after the date of Prop 65 listing, we estimated the change in concentrations over time for Californians compared with non-Californians, using a difference-in-differences model. We used quantile regression to estimate changes in exposure over time, as well as differences between Californians and non-Californians at the 25th, 75th, and 95th percentiles. RESULTS We found that concentrations of biomonitored chemicals generally declined nationwide over time irrespective of their inclusion on the Prop 65 list. Median bisphenol A (BPA) concentrations decreased 15% after BPA's listing on Prop 65, whereas concentrations of the nonlisted but closely related bisphenol S (BPS) increased 20% over this same period, suggesting chemical substitution. Californians generally had lower levels of biomonitored chemicals than the rest of the US population. DISCUSSION Our findings suggest that increased scientific and regulatory attention, as well as public awareness of the harms of Prop 65-listed chemicals, prompted changes in product formulations that reduced exposure to those chemicals nationwide. Trends in bisphenols and several phthalates suggest that manufacturers replaced some listed chemicals with closely related but unlisted chemicals, increasing exposure to the substitutes. Our findings have implications for the design of policies to reduce toxic exposures, biomonitoring programs to inform policy interventions, and future research into the regulatory and market forces that affect chemical exposure. https://doi.org/10.1289/EHP13956.

中文翻译：

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加州 65 号提案颁布后加州和美国 NHANES 生物监测暴露的趋势。


背景 有毒化学品在美国商业中的普遍存在促使一些州通过法律来减少接触。其中一项影响广泛的是加利福尼亚州的 65 号提案 （Prop 65），该提案建立了导致癌症、发育危害或生殖毒性的化学物质清单。该法律旨在阻止企业使用这些化学品，并最大限度地减少消费者接触。然而，一个关键问题仍未得到解答：加州 65 号提案是否减少了人群对所列化学品的暴露？目的 我们使用了美国疾病控制和预防中心 （CDC） 的国家生物监测数据来评估 Prop 65 对人群暴露的影响。方法 我们评估了美国国家健康和营养检查调查 （NHANES） 参与者中 37 种化学物质（包括邻苯二甲酸盐、酚类、VOCs、金属、PAH 和 PFAS）的血液和尿液浓度相对于化学品 Prop 65 列名时间的变化。其中，11 例在生物监测期之前、11 例在生物监测期期间和 4 例在生物监测期之后列出。其余 11 种未列入名单，但与 Prop 65 列出的化学品密切相关。在 Prop 65 列出日期之前和之后的生物监测数据可用的情况下，我们使用双重差分模型估计了加州人与非加州人相比浓度随时间的变化。我们使用分位数回归来估计暴露随时间的变化，以及加州人和非加州人在第 25 个、第 75 个和第 95 个百分位数的差异。结果我们发现，无论它们是否被列入 Prop 65 清单，全国生物监测化学品的浓度通常随着时间的推移而下降。 双酚 A （BPA） 浓度中位数在 BPA 列入 Prop 65 后下降了 15%，而未列入名单但密切相关的双酚 S （BPS） 的浓度在同一时期增加了 20%，表明存在化学替代。加利福尼亚人的生物监测化学品水平通常低于美国其他人口。讨论我们的研究结果表明，科学和监管关注的提高，以及公众对 Prop 65 所列化学品危害的认识，促使产品配方发生变化，从而减少了全国范围内对这些化学品的接触。双酚和几种邻苯二甲酸酯的趋势表明，制造商用密切相关但未列出的化学品取代了一些列出的化学品，从而增加了对替代品的接触。我们的研究结果对减少有毒物质暴露的政策设计、为政策干预提供信息的生物监测计划以及未来对影响化学品暴露的监管和市场力量的研究具有重要意义。https://doi.org/10.1289/EHP13956。