In an article published on October 29, 2018, by U.S. news provider Cable News Network (CNN), reporter Naomi Thomas informed about an epidemiological study that found a link between prenatal exposure to phthalates and delays in language development in children. The original study, conducted by researchers from Sweden and the U.S., was published in the peer-reviewed journal JAMA Pediatrics on the same day.
The study subjects included “963 [pairs of] children and mothers from Sweden, who participated in the Swedish Environmental Longitudinal Mother and Child, Asthma and Allergy Study (SELMA) and 370 [pairs of] mothers and children from the United States, who participated in the Infant Development and the Environment Study (TIDES).” The findings in the two cohorts were evaluated independently but published together to reinforce the common message.
Phthalate levels were measured in the mothers’ urine in the first trimester of pregnancy, and language development in the children was assessed by parent questionnaires either at two and a half years old (in the Swedish cohort) or at three years old (in the U.S. cohort). Children that had a vocabulary of less than 50 words were considered to have a language delay. Such children constituted around 10% in both Swedish and U.S. populations. The confounding factors controlled for in the study included the gender and “the age of the child, the age of the mother and the educational level of the mother.”
Shanna Swan from the Icahn School of Medicine at Mount Sinai, New York, U.S., senior author of the study, summarized that “the risk of language delay in mothers with high exposure versus low exposure . . . was double.” She further commented that the results from the U.S. and Swedish cohorts were “very consistent” and “supported each other.”
The two phthalates specifically highlighted for the strength of their associations with language delays were dibutyl phthalate (DBP, CAS 84-74-2) and benzyl butyl phthalate (BBP, CAS 85-68-7). The metabolite levels of these two substances in the mothers’ urine were “statistically significantly associated with language delay in both cohorts,” the authors said in the abstract of the peer-reviewed article. They concluded that their “findings, along with the prevalence of prenatal exposure to phthalates, the importance of language development, and the inconsistent results from a 2017 Danish study, suggest that the association of phthalates with language delay may warrant further examination.”
The “Danish study” was conducted with the Odense Child Cohort in Denmark. It found that “increased prenatal phthalate exposure was associated with lower scores in language development” of boys, but “no associations” were observed for girls.
Naomi Thomas (October 29, 2018). “Prenatal exposure to phthalates linked to language delays in children, study says.” CNN
Bornehag, C.-G., et al. (2018). “Association of prenatal phthalate exposure with language development in early childhood.” JAMA Pediatrics (published October 29, 2018).
Olesen, T. S., et al. (2018). “Prenatal phthalate exposure and language development in toddlers from the Odense Child Cohort.” Neurotoxicology and Teratology 65:34-41.