Early BPA Exposure May Affect Learning Ability

Another study has found a link between bisphenol A—BPA—and adverse health effects. This time, research using fish found that early BPA exposure may affect learning ability in adults.

UW-Milwaukee scientist Daniel Weber conducted tests with BPA and zebrafish and observed results similar to what he had seen when exposing zebrafish to the toxin mercury during early development, said Science Daily. The fish experienced “profound behavioral changes” immediately following hatching and in adulthood, said Weber.

Adult fish exposed to very small amounts of BPA as embryos experienced learning and memory problems when compared to unexposed fish. Weber, a researcher with the NIEHS Children’s Environmental Health Science Core Center at UWM, collaborated with Robert Tanguay at Oregon State University. This pilot study, funded by the Center, was the first to reveal neurobehavioral effects in zebrafish when exposed to BPA, said Science Daily. The zebrafish model was exposed to exposures comparable to what a human might be exposed to in the environment.

“What was amazing is that exposure only happened at the embryonic stage,” says Weber, “but somehow the wiring in the brain had been permanently altered by it. It’s an example of why children are not just little adults when it comes to gauging the effects of contaminants,” wrote Science Daily.

Because zebrafish mature in a few months, they’re a useful model to test toxicity effects over a lifetime, explained Science Daily, which noted that scientists can control chemical exposure conditions and timing with zebrafish because their embryos can live outside the mother.

Low BPA levels did not cause physical malformations or cardiac defects; however, without these, behavioral issues can occur, which the study confirms, said Tanguay, wrote said Science Daly. The test utilized a maze and involved conditioning the fish to chose one or another route. Unexposed fish learned in seven-to-ten trials, while exposed fish took two-to-three times as many trials. Nearly all the fish exposed to the highest levels were unable to learn the first portion of the task, said Science Daily.

For comparative purposes, some zebrafish embryos were exposed to either a natural or a synthetic estrogen at the same level as the BPA. Those fish expressed hyperactivity at the larval stage. Weber said that a number of behavioral outcomes become changed with BPA exposure and those changes—immediate hyperactivity and learning impairment at later stages—could be interconnected. “Being hyperactive—or even hypersensitive to an environmental stimulus—makes it difficult to learn,” said Weber. “We’ve seen that with children.” Tanguay’s lab plans on studying the molecular mechanism linking BPA to neurodevelopment interference; more behavioral research is also needed, said Weber.

BPA, a compound that uses a combination of phenol and acetone, enters food when it leeches from food and beverage containers, and has been approved by the U.S. Food & Drug Administration (FDA) for use in shatter-resistant polycarbonate plastic and durable epoxy resins. BPA leaches into products—hot or cold—and into the skin, from common items such as paper money, toilet paper, and receipts.

We’ve written that, in studies, BPA was linked to future cardiac issues and was found to also mix up the body’s hormones, tricking fat cells into taking in more fat or confusing the pancreas into releasing too much insulin, the hormone responsible to regulate the breakdown of fat and carbohydrates in the body. At least two BPA-breast cancer links and links to increased anxiety and depression in preschoolers exposed to BPA in the womb have been revealed. BPA has also been linked to toxic injury and implications in cardiovascular disease, intestinal problems, brain cell connection interference, increased risks of immune system diseases and disorders, problems with liver function testing, and interruptions in chemotherapy treatment. Increased risks for reproductive system disease, for instance, to uterine health and mammalian reproduction; a deadly uterine infection; premature puberty; Polycystic Ovarian Syndrome (PCOS) and other female fertility and endocrine issues; and erectile dysfunction and male sexual problems in males as young as the developing fetus have been linked to BPA. Very significantly, the National Institutes of Health (NIH) recently said that BPA may affect the development of young and unborn children.

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