When President Biden pledged that “science” and “truth” will guide decision-making, scientists the world over breathed a collective sigh of relief. The world is in a place where science should drive decision making. Ignoring or downplaying the existence of publicly available, science-driven conclusions about certain chemistries is troublesome – especially during a time when chemistry is providing important benefits to society.
One such example are the calls made by some to ban the entire chemical family, phthalates. We ask that people listen to the science, not the noise. It is critical to take into account the significant differences among the many compounds that are part of this chemical family. Rather than using a one-size-fits-all approach, let’s have a science-based discussion about the nature of these chemicals, how they differ from each other, and what they do affect – and what they don’t – in order to determine the risks, if any, to human health and the environment.
There are reports claiming a connection between child exposure to phthalates and increased risk of negative impacts on reproductive health and brain development. We are concerned these reports create hysteria in order to attract readers and gain buy-in to fear tactics, rather than benefiting discussions around chemical safety and human health. Although serious inquiries into chemical safety and human reproductive health are warranted, the alleged links in Dr. Shanna Swan’s work between exposure to DINP and DIDP and reduced sperm count are inconsistent with stronger, more credible studies on the same subject.
The term “phthalate” refers to a family of chemicals that happen to share the same functional group, but which are structurally, functionally and toxicologically distinct from each other. Broadly, there are two distinct categories – low molecular weight (LMW) and high molecular weight (HMW) phthalates. HMW phthalates are among the most thoroughly studied families of compounds in use, and numerous government regulatory agencies, including the European Chemicals Agency (ECHA) (2018), the Australian National Industrial Chemicals Notification and Assessment Scheme (NICNAS) (2012, 2015), and Canada’s Ministry of Environment and Climate Change and Ministry of Health (2020), have found, after rigorous regulatory review, that HMW phthalates like DINP and DIDP are safe as currently used.
With respect to the concern over reproductive effects, the ECHA RAC (2018) found no clear evidence of any association between phthalate exposures and sperm parameters, and concluded that “no classification for DINP for either effects on sexual function and fertility, or for developmental toxicity is warranted.” With respect to DIDP, the US Consumer Product Safety Commission completed a hazard assessment on its ability to impact reproductive fertility and fetal development in humans in 2017. It found no concern with exposure to children, pregnant women or other susceptible individuals with an adequate margin of safety. As a result, the use of DIDP in children’s toys and childcare articles is no longer restricted in the United States. DINP and DIDP are two of the most heavily studied chemicals, and studies continue to confirm no connection between exposure to these compounds and adverse health effects. The data is so abundant that manufacturers have requested an evaluation of the risks and hazards under the Environmental Protection Agency’s Toxic Substances Control Act.
Further, recent systematic reviews from Radke et al. and Zhang et al. pulled together the data available on neurobehavioral and cognition effects and concluded that there was no association between DINP and DIDP and neurobehavioral or cognitive effects. The results of the Zhang et al. systematic review demonstrate that DINP and DIDP are not associated with neurobehavioral or cognitive health effects in children. Since exposure to DINP and DIDP occurred during a sensitive developmental period, it is anticipated that a single exposure during this same time period would also produce no adverse effects.
While we are encouraged by continuous research efforts into the science and health of phthalates, we are concerned about the over-interpretation of studies that have not established a causal link between HMW phthalates and human adverse health effects. These reports fail to consider all phthalates individually and consistently ignore or downplay the existence of science-based, authoritative conclusions regarding the safety of HMW phthalates.