Phthalates, synthetic chemicals widely used in various packaging products, contributed to over 56,000 preterm births in 2018, according to New York University (NYU) researchers. The lost economic productivity and additional medical care costs due to phthalate-induced preterm birth in 2018 ranged between US$1.63 billion – US$8.14 billion.

The researchers identified associations of phthalate exposure, commonly found in food containers, with decreased gestational age in a large and diverse sample representative of the US.

The patterns of association suggest that replacements of di-2-ethylhexyl phthalate (DEHP), an organic plasticizer, are driving the increase in preterm birth.

This finding is of “great concern,” say the researchers, because more harmful compounds like diisodecyl phthalate (DiNP), diisodecyl phthalate (DiDP) and 1,2-cyclohexane dicarboxylic acid diisononyl ester are commonly replacing DEHP in food packaging.

A “substantial” contribution
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The scientists controlled for confounding factors such as the mothers’ age, tobacco use, race and education, and estimated phthalate exposure contributed to more than 56,000 preterm births in the US in 2018.

Preterm is defined as babies born alive before 37 weeks of pregnancy are completed, according to the World Health Organization.

“In a large, diverse US sample, DEHP, DiDP, DiNP and phthalic acid exposures were associated with decreases in gestational age and increased preterm birth risk, suggesting opportunities for prevention,” stress the researchers.

“The contribution is substantial, with 56,595 preventable preterm birth cases. The adverse consequences of chemically similar phthalates to DEHP suggest a need to regulate chemicals with similar properties as a class.”

Filling research gaps
The researchers used extant data from the US National Institutes of Health Environmental Influences on Child Health Outcomes (ECHO) Program from 1998 to 2022 to study associations of 20 phthalate metabolites with gestational age at birth, birthweight, birth length and birthweight for gestational age z-scores.

The ECHO consortium combines data from many cohorts representing diverse populations and exposures over time, which allowed for evaluating the effect of replacement phthalates on birth outcomes.

Existing studies have methodological limitations, and potential effects of DEHP replacements are “poorly characterized,” find the researchers.

“Attributable fractions and costs have not been quantified, limiting the ability to weigh trade-offs involved in ongoing use. We aimed to leverage a large, diverse US cohort to study associations of phthalate metabolites with birthweight and gestational age, and estimate attributable adverse birth outcomes and associated costs.”

Strengths of the analysis include the large sample size, high quality of laboratory analyses, harmonization approach, multiple robustness checks and the specificity of the effect to gestational age.