Mice exposed to low doses of arsenic in drinking water to developing lung cancer

Mice exposed to low doses of arsenic in drinking water to developing lung cancer -

Mice exposed to low doses of arsenic in the water, even drinking that could consume some developed lung cancer, the National Institutes of Health researchers have found.

levels of arsenic in public drinking water can not exceed 10 parts per billion (ppb), which is the standard set by the US Agency for Environmental Protection. However, there are no established standards for private wells, from which millions of people get their drinking water.

In this study, the concentrations given to mice in their drinking water was 50 parts per billion (ppb), 500 ppb and 5000 ppb. 50 ppb is the lowest concentration that was tested in an animal study, and the researchers say that because of different metabolism rate, the mice need to be exposed to higher concentrations of arsenic in the drinking water humans to achieve the same biological dose and similar health effects.

The researchers used a model that mimics the way humans are exposed to arsenic during their lifetime. In the study, mice received arsenic three weeks before breeding and during pregnancy and lactation. Arsenic was then given to the offspring after weaning, and while an adult at relevant concentrations to human exposure. The researchers examined tumors in adult offspring.

"This study is the first to show the development of tumors in animals exposed to very low levels of arsenic, similar levels to which humans may be exposed," said Michael Waalkes, Ph. D., lead author on the paper and director of the National Laboratory of Toxicology Program (NTP). "The results are unexpected and certainly cause for concern."

Arsenic is present in the environment as a naturally occurring substance or due to contamination from human activity. Arsenic can be found in many foods including grains, fruits and vegetables, where it is present due to the absorption of soil and water. This study focused on inorganic arsenic, which often occurs in excess in drinking water of millions of people worldwide, and has previously been shown to be carcinogenic to humans.

In the study, more than half of the male offspring mice developed significant increases in benign and malignant lung tumors in the two lower doses (50 ppb and 500 ppb). female offspring also developed benign tumors with lower concentrations. Interestingly, the researchers did not find a significant increase in lung tumors in both sexes at the highest dose (5000 ppb).

"Although this is a single study adds to a growing body of evidence showing adverse health effects of very low exposures to arsenic, raising the possibility that no level arsenic appears to be safe, "said Linda Birnbaum, Ph.D., director of the National Institute of sciences environmental health (NIEHS) and NTP.