Low-level Arsenic Exposure Before Birth Associated with Early Puberty in Female Mice
News Sep 01, 2015
Female mice exposed in utero, or in the womb, to low levels of arsenic through drinking water displayed signs of early puberty and became obese as adults, according to scientists from the National Institutes of Health.
The finding is significant because the exposure level of 10 parts per billion used in the study is the current U.S. Environmental Protection Agency standard, or maximum allowable amount, for arsenic in drinking water.
The study, which appeared online August 21 in the journal Environmental Health Perspectives, serves as a good starting point for examining whether low-dose arsenic exposure could have similar health outcomes in humans.
Scientists from the National Institute of Environmental Health Sciences (NIEHS), part of NIH, divided pregnant mice into three groups. The control group received no arsenic in its drinking water, while the two experimental groups received either the EPA standard of 10 parts per billion of arsenic or 42.5 parts per million of arsenic, a level known to have detrimental effects in mice.
One part per billion is a thousand times smaller than one part per million. The mice were exposed during gestation, between 10 days after fertilization and birth, which corresponds to the middle of the first trimester and birth in humans.
"We unexpectedly found that exposure to arsenic before birth had a profound effect on onset of puberty and incidence of obesity later in life," said NIEHS reproductive biologist and co-author Humphrey Yao, Ph.D. "Although these mice were exposed to arsenic only during fetal life, the impacts lingered through adulthood."
The impacts Yao is referring to are obesity and early onset puberty, particularly in female mice. The researchers did not examine in this study whether males also experienced early onset puberty, but they did confirm that male mice exposed to arsenic in utero also displayed weight gain as they aged. Both the low and high doses of arsenic resulted in weight gain.
According to lead author NIEHS biologist Karina Rodriguez, Ph.D., the research team performed the experiment in three separate batches of mice, each containing a control and two experimental groups, and achieved similar results.
She said although the biological process responsible for these effects remains unknown, the study highlights the need to continue researching long-term impacts of what mothers eat, drink, and breathe during pregnancy on the welfare of the offspring.
"It's very important to study both high doses and low doses," said Linda Birnbaum, Ph.D., director of NIEHS and the National Toxicology Program. "Although the health effects from low doses were not as great as with the extremely high doses, the low-dose effects may have been missed if only high doses were studied."
Sanchi Oil Spill Contamination Could Take Three Months to Reach MainlandNews
Water contaminated by the oil currently leaking into the ocean from the Sanchi tanker collision is likely to take at least three months to reach land, and if it does the Korean coast is the most likely location. However, the oil’s fate is highly uncertain, as it may burn, evaporate, or mix into the surface ocean and contaminate the environment for an extended duration.READ MORE
Understanding How Conditions Affect Environmental DNA AnalysisNews
Environmental DNA analysis makes it possible to detect water organisms without having to capture them first. For the first time, a team systematically investigated the effect of various environmental factors on environmental DNA analyses. By doing so, the researchers have made an important step towards the standardized application of this method for the monitoring of water bodies.READ MORE
Surfers Three Times More Likely to Have Antibiotic-Resistant Bacteria in GutsNews
Regular surfers and bodyboarders are three times more likely to have antibiotic resistant E. coli in their guts than non-surfers, new research has revealed. The Beach Bums study asked 300 people, half of whom regularly surf the UK's coastline, to take rectal swabs. Surfers swallow ten times more sea water than sea swimmers, and scientists wanted to find out if that made them more vulnerable to bacteria that pollute seawater, and whether those bacteria are resistant to an antibiotic.READ MORE