We did the math. EPA’s calculations of male reproductive harm from DCHP are off by 50,000x.

Despite decades of scientific research and evaluation linking phthalates to male reproductive harm and infertility, these chemicals remain largely unregulated in the United States. There is little indication this will change based on EPA’s recent draft risk evaluation of dicyclohexyl phthalate (DCHP), which relies on flawed scientific methods that significantly underestimate health risks. So, PRHE scientists recalculated the risk assessments using scientifically valid methods developed by the World Health Organization. The findings are alarming.

The toxic effects of DCHP are well-documented in both animal and human studies. Like other phthalates, which are widely used as plasticizers and found in everyday products from adhesives, food packaging, and fragrances to vinyl flooring and automotive parts, exposure to DCHP during critical windows of development — especially in utero — has been shown to disrupt the formation of the male reproductive tract. These effects include undescended testes, malformed genitals, reduced testosterone synthesis, and decreased sperm production. Collectively, these effects are known in the scientific literature as “phthalate syndrome.” Notably, these outcomes have been observed as a result of very low levels of exposure.

While EPA did consider male reproductive toxicity in its DCHP risk evaluation, the Agency relied on outdated risk assessment methodologies that assume a “safe” threshold below which no adverse effects occur. This threshold-based approach fails to account for the range of susceptibilities in the population, including genetics, age, pre-existing conditions, or how even low exposures to DCHP can lead to adverse health effects.

Using methods developed by the World Health Organization, which better quantitates risks for all levels of exposures, we reanalyzed EPA’s estimated exposure data to calculate risks of noncancer health effects. Our findings show that the exposure level EPA deemed “safe” for the general population corresponds to an estimated risk level of 1-in-20 for male reproductive harm — 50,000x higher than EPA’s own risk benchmark for cancer risk (1-in-1,000,000). This gross underestimation undermines public health protection.

EPA also failed to address cumulative exposures to other phthalates and non-chemical stressors in its DCHP risk evaluation. Americans are exposed to multiple hazardous phthalates at once, many of which can increase the risk of male reproductive harm. When combined, their effects can amplify serious health effects. EPA failed to consider these real-world exposures or consider exposures to non-chemical stressors, like pre-existing disease, poverty, food insecurity, healthcare inequity, and racism, which can increase susceptibility to harm from chemical exposures.

To adequately evaluate these real-world exposures, EPA must employ cumulative risk assessment (CRA) tools. Although EPA recently proposed to conduct a CRA for several phthalates, including DCHP, its current methods fail to fully capture real-world risks.

EPA’s latest draft risk evaluation for DCHP follows the same egregious pattern as EPA’s assessments for two other phthalates, DIDP and DINP — both of which were initiated at the request of chemical manufacturers and released last year — continuing further down a dangerous road in the Agency’s implementation of the Toxic Substances Control Act (TSCA). This pattern of failure to adequately regulate phthalates directly contradicts the current Administration’s “Make America Healthy Again” campaign, which promises to address rising infertility and toxic chemical exposure.

 We submitted detailed scientific comments on behalf of scientists, academics, and public health professionals urging EPA to adopt the best available scientific methods in its draft risk evaluation for DCHP, including:

1. abandoning the risk threshold approach and adopting a probabilistic approach to risk quantification that accounts for low-dose effects and
2. conducting a CRA that reflects real-world exposures to multiple phthalates and non-chemical stressors.

Without stronger regulation, phthalates — a hazardous class of chemicals — will continue to be manufactured, used, and disposed of with minimal oversight, and undermine public health.

About the author

Abena BakenRa, MPH is a Science Associate for the Science, Policy & Engagement team at PRHE. Through her research, Abena aims to address health effects in underserved and vulnerable communities, especially among historically oppressed groups. She received her MPH from University of California, Berkeley, specializing in Epidemiology and Biostatistics.