Gradient, Seattle, WA, USA.
Gradient, Boston, MA, USA.
Inhal Toxicol. 2021 Aug-Dec;33(9-14):295-307. doi: 10.1080/08958378.2021.1998258. Epub 2021 Nov 17.
The United States Environmental Protection Agency (US EPA) is currently refining its approach for risk assessments conducted under the amended Toxic Substances Control Act (TSCA), largely based on recommendations from the National Academies of Sciences, Engineering, and Medicine (NASEM). We identified several issues with the current TSCA risk assessment approach that were not addressed by NASEM in its recommendations. Here, we demonstrate these issues with a case study of the 'Risk Evaluation for Asbestos, Part 1: Chrysotile Asbestos,' which US EPA released in December 2020. In this evaluation, US EPA found that occupational and some consumer uses of automotive brakes and clutches that contain asbestos result in unreasonable risks. These risks were calculated from estimated exposures during brake work and an inhalation unit risk (IUR) developed for chrysotile asbestos. We found that US EPA overestimated risk as a result of unrealistic inputs to both the exposure and toxicity components of the risk equation, and because the Agency did not fully consider relevant epidemiology and toxicity evidence in its systematic review. Our evaluation demonstrates areas in which the TSCA risk assessment approach could be improved to result in risk evaluations that are supported by the available scientific evidence.
美国环境保护署（EPA）目前正在根据美国国家科学院、工程院和医学院（NASEM）的建议，改进其在经修正的《有毒物质控制法》（TSCA）下进行的风险评估方法。我们发现当前的 TSCA 风险评估方法存在一些问题，而 NASEM 在其建议中并未涉及这些问题。在这里，我们通过对美国环保署 2020 年 12 月发布的“石棉风险评估，第 1 部分：温石棉石棉”案例研究来说明这些问题。在这项评估中，美国环保署发现含有石棉的汽车刹车和离合器的职业和一些消费者用途会导致不合理的风险。这些风险是根据刹车工作期间的估计暴露量和温石棉开发的吸入单位风险（IUR）计算得出的。我们发现，由于风险方程的暴露和毒性部分的输入不切实际，以及环保署在系统审查中没有充分考虑相关的流行病学和毒性证据，美国环保署高估了风险。我们的评估表明，TSCA 风险评估方法可以在哪些方面得到改进，以产生有可用科学证据支持的风险评估。
