Mice exposed to Bisphenol-A (BPA) and other endocrine-disrupting chemicals give less care to their offspring. University of Missouri researchers who conducted the study say the finding could apply to human parenting as well.

“Endocrine-disrupting chemicals like BPA mimic the steroid hormones that establish the ‘circuitry’ for the adult female brain during early development, but little was known about how this chemical might affect the father’s behavior,” says Cheryl Rosenfeld, associate professor of biomedical sciences at University of Missouri.

The Food and Drug Administration banned the production of baby bottles and sippy cups containing BPA in 2012.

“Our study set out to address this critical void by exposing both males and females to the endocrine-disrupting chemicals BPA and Ethinyl estardiol (EE), the main active component of birth control pills, and examine the repercussions of rearing offspring.”

It is only in a minority of species that both male and female partners contribute to child-rearing. Among them are humans, and a species of California mouse (Peromyscus californicus) used by the researchers for the study.

Male mice partners show cooperative care of the pups from birth to weaning through cleaning, grooming, and giving warmth by huddling over their young when females leave the nest. Poor care could lead to negative consequences for the young.

Diets Compared

In the study, researchers raised female California mice on one of three diets. One contained BPA, the second contained concentrations of EE, and the third was free of endocrine disruptors. Males were developmentally exposed to the same three diets.

The male and female mice were them paired randomly. Because California mice are monogamous, one male was paired with a single female for the length of the study.

After being paired, parents and offspring were watched for a range of behaviors, for example, duration the females spent nursing the pups, male and female grooming of the pups, and time spent in and out of the nest by both parents. Throughout the study, development of the pups, including body weight gain and temperature, was monitored.

Rosenfeld says:

“We found that females who were exposed early on to BPA spent less time nursing, so the pups likely did not receive the normal health benefits ascribed to nursing.

Likewise, we found that developmental exposure of males and females to these endocrine-disrupting chemicals resulted in their spending more time out of the nest and away from their pups, further suggesting that biparental care was reduced.”

Surprisingly, it also appears that females can detect whether or not the male is compromised by BPA and adjusts her parental care accordingly.

Williams SA, Jasarevic E, Vandas GM, Warzak DA, Geary DC, Ellersieck MR, et al. (2013) Effects of Developmental Bisphenol A Exposure on Reproductive-Related Behaviors in California Mice (Peromyscus californicus): A Monogamous Animal Model. PLoS ONE 8(2): e55698. doi:10.1371/journal.pone.0055698

Photo: Wellcome Library, London, Creative Commons by-nc-nd 4.0

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