Sensationalized headlines, misinterpreted results, correlation mistaken for causation, and results that are yet to be replicated... these are just a few of the problems one science writer says to watch out for in his guide for spotting bad science. As he says, “being able to evaluate the evidence behind a scientific claim is important. Being able to recognize bad science reporting, or faults in scientific studies, is equally important.”
Recently, a CNN article cited a study claiming that phthalate exposures are linked to 107,000 premature deaths, costing the United States economy between $40 and $47 billion dollars a year in lost economic productivity.
The researchers behind this claim acknowledge that their study provides nothing more than a tenuous association,[1] stating “more research would be needed to provide conclusive proof that the chemicals cause early death, as well as the mechanism for how this happens.” Yet, in the absence of such corroborating evidence, the researchers go on to advocate for sweeping regulations that would almost completely remove phthalates and plastics from commerce.
"However, I'm never going to tell you this is a definitive study," Trasande told CNN. "It is a snapshot in time and can only show an association."
Even more disappointing is that the the CNN article ignored a key point - that the research demonstrated that not all phthalates are the same. The researchers found that “mono-(carboxyoctyl) phthalate [DINP] and mono-(carboxynonyl) phthalate [DIDP] were not associated with mortality.” The researchers dismiss this lack of association by claiming that “due to the lag between measurement and mortality, we were unable to evaluate replacements of DEHP that have emerged over the past decade, including diisononyl (DINP) and diisodecylphthalate (DIDP).”
Let’s be clear on the facts. Publicly available data confirm that DINP and DIDP have been in commerce for more than 50 years. The EU Risk Assessment Report on DINP reports the commercial availability of DINP as early as 1973.[2] Plasticizer consumption data in the United States reported nearly equal use of DINP and DEHP as far back as 1995, and as DEHP consumption has decreased in the US DINP consumption in the US has increased since then.[3] Yet, per CDC data, exposures remain extremely low.
In other words, the lack of association for DINP and DIDP isn’t because exposures have only “emerged over the past decade.” Rather, the study affirms the conclusions that other regulatory agencies have reached, that DINP and DIDP are safe as used in existing applications.
The term “phthalates” simply refers to a family of chemicals that happen to be structurally similar, but which are functionally and toxicologically distinct from each other. This distinction is critical yet often missed in news outlets that cover these complex and extensive chemical families. It is critical to take into account the significant differences among compounds that are part of a chemical family. Rather than a one-size-fits-all approach, we need a fact-based discussion about how these compounds differ from each other, what they do affect — and what they don’t — in terms of human and environmental health.
Studies such as these fail to consider all phthalates individually and consistently ignore or downplay the existence of science-based, authoritative conclusions regarding the safety of high molecular weight phthalates. Not making this distinction and only broadly using the term “phthalate,” misleads readers to believe all phthalates are harmful to human health. In the past six years, numerous government regulatory agencies, including the European Chemicals Agency (ECHA), the Australian National Industrial Chemicals Notification and Assessment Scheme (NICNAS), and Canada’s Ministry of Environment and Climate Change and Ministry of Health, have found, after rigorous regulatory review, that DINP and DIDP are safe as currently used.
We support the use of robust, and reproducible science in protecting public health. Unfortunately, this latest study is neither.
[1] "However, I'm never going to tell you this is a definitive study," Trasande told CNN. "It is a snapshot in time and can only show an association." Culled from Phthalates: Synthetic chemical in consumer products linked to early death, study finds - CNN.
[2]EU Risk Assessment Report (europa.eu)
[3] IHS Markit Plasticizers Chemical Economics Handbook. 2018, 2021.
