Silent Spring Institute, Newton, Massachusetts, USA.
School of Public Health, University of California, Berkeley, California, USA.
Environ Health Perspect. 2024 Oct;132(10):107007. doi: 10.1289/EHP13956. Epub 2024 Oct 21.
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?
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.
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.
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.
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.
美国商业领域有毒化学物质的流行促使一些州通过法律来减少接触。其中一个影响广泛的法律是加州的第 65 号提案（Prop 65），该提案列出了一些会导致癌症、发育损害或生殖毒性的化学物质。该法律旨在阻止企业使用这些化学物质，并尽量减少消费者的接触。然而，一个关键问题仍未得到解答：Prop 65 是否降低了列出化学物质的人群暴露水平？
我们使用美国疾病控制与预防中心（CDC）的全国生物监测数据来评估 Prop 65 对人群暴露水平的影响。
我们评估了 37 种化学物质（包括邻苯二甲酸酯、酚类、挥发性有机化合物、金属、多环芳烃和全氟和多氟烷基物质）在与化学物质列入 Prop 65 时间相关的美国国家健康和营养检查调查（NHANES）参与者的血液和尿液浓度中的变化。其中，11 种在生物监测期之前列入，11 种在生物监测期期间列入，4 种在生物监测期之后列入。其余 11 种未列入，但与列入 Prop 65 的化学物质密切相关。对于有列入 Prop 65 之前和之后的生物监测数据的化学物质，我们使用差异中的差异模型估计加利福尼亚州与非加利福尼亚州之间随时间变化的浓度变化。我们使用分位数回归来估计随时间的暴露变化，以及加利福尼亚州和非加利福尼亚州在第 25、75 和 95 百分位数的差异。
我们发现，无论这些化学物质是否列入 Prop 65，其生物监测浓度总体上随时间呈下降趋势。在双酚 A（BPA）列入 Prop 65 之后，BPA 的浓度下降了 15%，而与其密切相关但未列入的双酚 S（BPS）的浓度在此期间上升了 20%，表明存在化学物质替代。加利福尼亚州的参与者通常比美国其他地区的参与者具有更低的生物监测化学物质水平。
我们的研究结果表明，科学和监管关注度的增加，以及公众对列入 Prop 65 的化学物质危害的认识提高，促使产品配方发生了变化，从而降低了全国范围内对这些化学物质的暴露。双酚和几种邻苯二甲酸酯的趋势表明，制造商用与其密切相关但未列入的化学物质替代了一些列入的化学物质，增加了替代品的暴露。我们的研究结果对制定减少有毒暴露的政策、为政策干预提供信息的生物监测计划以及未来研究影响化学物质暴露的监管和市场力量具有重要意义。https://doi.org/10.1289/EHP13956.
