Over the past 3 decades, in a series of studies on some of the most extensively studied toxic chemicals and pollutants, scientists have found that the amount of toxic chemical linked with the development of a disease or death—which is central to determining "safe" or "hazardous" levels—is proportionately greater at the lowest dose or levels of exposure. These results, which are contrary to the way the United States Environmental Protection Agency (EPA) and other regulatory agencies assess the risk of chemicals, indicate that we have underestimated the impact of toxic chemicals on death and disease. If widely disseminated chemicals and pollutants—like radon, lead, airborne particles, asbestos, tobacco, and benzene—do not exhibit a threshold and are proportionately more toxic at the lowest levels of exposure, we will need to achieve near-zero exposures to protect public health.

在过去的30年中，在对一些最广泛研究的有毒化学物质和污染物进行的一系列研究中，科学家们发现，有毒化学物质的量与疾病或死亡的发展有关，这对于确定“安全”至关重要或“危险”水平-在最低剂量或最低暴露水平下成比例增加。这些结果与美国环境保护局（EPA）和其他监管机构评估化学品风险的方式相反，表明我们低估了有毒化学品对死亡和疾病的影响。如果广泛传播的化学物质和污染物（例如ra，铅，空气中的微粒，石棉，烟草和苯）没有表现出阈值，并且在最低暴露水平下具有更大的毒性，