Researchers discover correlation between BPA exposure, reproductive dysfunction
UCLA researchers demonstrated that BPA, a chemical used in many plastics, caused fertility defects in worms that could still be observed five generations later. (Daniel Leibowitz/Daily Bruin staff)
By Joseph Ong
July 16, 2018 12:20 am
UCLA researchers discovered that exposure to some chemicals may cause reproductive defects in future generations of humans.
In a study published in May, the researchers in the laboratory of Patrick Allard, an assistant professor in the UCLA Institute for Society and Genetics, demonstrated that bisphenol A, a chemical used to strengthen many plastics, caused fertility defects in worms that could still be observed five generations after the parent worms were exposed to BPA. The research suggests environmental chemicals may have similar effects on human health for many generations.
“(Seeing the effects of BPA over many generations) was surprising and very concerning,” said Lisa Truong, a graduate student working in the Allard Laboratory and an author of the study.
BPA is a chemical found in plastics, such as water bottles, that can leak into the user’s diet, according to the National Institute of Environmental Health Sciences. Previous studies have shown that BPA causes developmental defects in newborn animals and may affect human reproduction and development.
Allard said his lab studies how germ cells, the cells that make sperm and eggs, pass on their memory of environmental conditions, such as diet and chemical exposure. Cells keep track of their memory across generations by tagging their DNA with molecular markers and passing on those DNA marks to the embryo at fertilization, he said.
“We found that (the cellular process of marking DNA) is highly influenced by the environment,” he said.
Throughout development, cells mark their DNA to activate or silence particular genes, allowing the cell to choose carefully which proteins are necessary for that specific stage in development, Truong said.
The researchers found reproductive cells from worms that had parents exposed to BPA had fewer silencing marks. This misregulation of DNA marks led to the inappropriate activation of genes in the reproductive cells and caused fertility defects, according to the study.
Jessica Camacho, a graduate student in the Allard lab and the lead author of the study, said she observed that worms whose parents were exposed to BPA had more cellular damage in their reproductive cells and produced fewer viable offspring.
“We saw a lot of defects in the female germline (of worms whose parents were exposed to BPA),” Camacho said. “To see (infertility) double is very significant.”
Camacho said she saw this effect even five generations after the parents were exposed to BPA, demonstrating that even offspring who had not been exposed to BPA still inherited the effects of BPA exposure.
Allard said his lab is expanding its work to see if other chemicals, like nicotine from cigarettes or THC from marijuana, also have transgenerational effects. Some of these chemicals have already been implicated in reproductive health, but whether or not their effects carry on through multiple generations, as BPA does, is unknown.
Allard said he is hopeful his work will raise awareness about the relationship between environmental chemicals and human health.
“If we know what we’re being exposed to now (affects the health of future generations), then let’s act quickly to determine the safety of those chemicals, because our decisions may impact many more people than we originally thought,” he said.