Plastic additive meant to replace toxic phthalates linked to lower birth weights, study finds
Prenatal exposure to a plasticizer introduced to replace harmful plastic additives is linked to lower birth weights, according to a new study led by NYU Langone Health researchers.
The study, published on Oct. 4 in Environment International, adds to growing evidence that replacement chemicals themselves can pose their own health risks.
Di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH) was originally introduced by plastic manufacturers to replace phthalates, a group of synthetic chemicals used primarily to make plastic more flexible and durable. Phthalates are linked to a variety of health impacts, including preterm births, low birth weights, hormone disruption, decreased fertility, heart and behavioral problems, and other issues.
Researchers at NYU analyzed 6,617 pregnancies and found that higher levels of DINCH were linked to lighter and smaller newborns.
For every 10-fold increase in exposure to DINCH, there was a 27-gram reduction in newborn birth weight.
Babies born to mothers with higher urinary DINCH levels had a higher chance of being classified as “small for gestational age”—meaning their birth weight ranked below the 10th percentile compared to other babies born at the same stage of pregnancy.
“Even small differences in birth size can matter because fetal growth problems can raise the risk for heart disease, learning difficulties, obesity, and other issues that can echo into adolescence and adulthood,” lead author Leonardo Trasande, Professor of Pediatrics at NYU Grossman School of Medicine, said in a press release.
These results raise questions on whether swapping out phthalates for new plasticizers like DINCH create a new set of health concerns—a phenomenon scientists refer to as a “regrettable substitution.”
Shelley Liu, associate professor at the Icahn School of Medicine at Mount Sinai, said that regrettable substitution is unfortunately common when certain chemicals are phased out of use due to adverse effects.
“Because those chemicals are useful in some way, like ortho-phthalates help make plastics more flexible, industry then looks to replace those chemicals with something else that has a similar function,” Liu said.
The study also found that Hispanic mothers or those that had lower levels of education were more likely to have children affected by DINCH.
Liu said that while the study itself doesn’t interrogate potential exposure sources that these participants had, “food packaging and household products may be important exposure sources, and the study findings suggest that we could do better at regulating and monitoring these chemicals to make sure we can minimize our exposure as a society.”
Researchers say the study makes the case for stronger oversight of chemicals used in food packaging and other household products, by requiring they be “tested before they are introduced to the market, instead of after they are connected to health concerns,” said Trasande.
In 2017, the Consumer Product Safety Commission (CPSC) finalized a rule adding five specific phthalates to a list of restricted chemicals in children’s toys and childcare products. The list did not include products used during pregnancy.
However, researchers at Stanford University and the University of North Carolina at Chapel Hill published a study in June analyzing plasticizers that were recently introduced to replace toxic chemicals like phthalates, and found that the newer substances had similar health effects to the chemicals they replaced.
“The issue is that the replacements may not be well studied in terms of their health impacts before they’re put into use, and they may themselves have negative health impacts,” Liu said.
Featured image: Kateryna Hliznitsova for Unsplash+
