Arsenic In Drinking Water

‘Safe’ Levels Of Arsenic In Drinking Water Bad for Pregnant,
Lactating Mice And Offspring

This is just one reason to get a Water Purifier

News Posted: June 04, 2012

Exposure to arsenic in drinking water at the level the U.S.
Environmental Protection Agency (EPA) currently deems as safe in the
United States (10 parts per billion) induces adverse health outcomes in
pregnant and lactating mice and their offspring, concludes a study led
by Joshua Hamilton of the Marine Biological Laboratory (MBL) and
Courtney Kozul-Horvath at Geisel School of Medicine at Dartmouth. The
team is part of the Dartmouth Superfund Research Program on Toxic

Pregnant and breastfeeding mothers who consumed low levels (10 ppb)
of arsenic in their drinking water, the scientists found, exhibited
significant disruption in their lipid metabolism, leading to diminished
nutrients in their blood and in their breast milk. As a result, their
offspring showed significant growth and development deficits during the
postnatal period before weaning. Birth outcomes such as litter size and
length of gestation were unaffected.

“The pups were essentially malnourished; they were small and
underdeveloped,” Hamilton says. Once the pups were switched to milk from
a mother who had not consumed arsenic, their growth deficits reversed,
although only the males fully caught up with the pups that had had no
arsenic exposure.

The U.S. EPA recently lowered the Maximum Contaminant Level for
arsenic to 10 ppb in public water supplies — a regulated level that is
considered “safe” for a lifetime of exposure — yet concentrations of 100
ppb and higher are commonly found in private, unregulated well water in
regions where arsenic is geologically abundant, including upper New
England (Massachusetts, New Hampshire, Maine), Florida, and large parts
of the Upper Midwest, the Southwest, and the Rocky Mountains.

“This study raises a couple of issues. First, we have to think again
about whether 10 ppb arsenic as a U.S. drinking water standard is safe
and protective of human health,” says Hamilton, who is the MBL’s chief
academic and scientific officer and a senior scientist in the MBL Bay
Paul Center.

“Second, this study reiterates an emerging idea in toxicology that
pregnant women and their offspring are uniquely sensitive to chemicals
in their environment,” Hamilton says. “There is a special window of
vulnerability for both of them.” Third, says Hamilton, “If you are on a
private water system, particularly in a region with high arsenic, have
your water tested so that you know what you are drinking.”

The levels of arsenic and other regulated chemicals in public
drinking water are published by water systems and readily available to
consumers. In most states, the Department of Environmental Protection or
its equivalent will also test an individual’s sample of private well
water for arsenic and other chemicals. If the concentration of arsenic
is of concern, Hamilton says, the best options for private well owners
are drinking bottled water or buying a remediation system, such as
reverse osmosis, that will remove arsenic. Additional information and
resources can be found on the Dartmouth Toxic Metals web site .

Based on this and prior studies (Environ. Hlth. Perspect. 2009),
Hamilton and colleagues posit that exposure to low levels of arsenic may
act as a predisposing factor, in which a second stress is needed to
induce adverse health affects. In this study, pregnancy and lactation
acted as that secondary stress. In the prior study, Hamilton’s group
demonstrated that arsenic suppressed immune function, leading to
dramatically greater effects of a flu infection in mice.

Offspring are also uniquely sensitive to environmental chemicals
because “they are developing rapidly. It’s not hard for very low doses
of a chemical to have big effects on a developing animal,” Hamilton

In the current study, the mothers who were exposed to arsenic had
significantly lower triglyceride concentrations in their serum and
breast milk than normal, indicating the process of fat metabolism and
storage in their bodies was compromised.

“Normally, the body is very good at storing fat and glucose for later
use,” Hamilton says. “Up to a certain point, if a mother is malnourished
during and after pregnancy, the offspring will not be compromised,
because her body uses nutrients it has stored to nourish the baby. Her
body will basically ‘eat itself’ to provide for the baby.” However,
because this protective mechanism was disrupted in the arsenic-exposed
mothers, they could provide less nutrients to their pups via breast

The arsenic-exposed mothers also displayed a condition known as
hepatic steatosis or “fatty liver,” in which fat accumulates abnormally
in the liver.

As early as day 10 after birth, the pups of arsenic-exposed mothers
showed significant deficits in growth, as evidenced by body weight. At
the typical time of weaning (21 days after birth), many of the
arsenic-exposed offspring were so small that it was not feasible to
separate them from their mothers.

“The message here is, ‘Pay attention to your total arsenic exposure,
both in drinking water and also in food.’” Hamilton says. “Pregnant
women, especially, need to be very careful and protective of their
health. Environmental chemicals such as arsenic, along with tobacco,
alcohol, drugs — all of these chemicals are potential stressors to
pregnant women and their offspring.”

“The research conducted by Dr. Hamilton and Dr. Kozul-Horvath is an
important component of our Superfund Research Program (SRP) at
Dartmouth,” says Bruce Stanton, Dartmouth SRP Director.  “These
significant results add to the body of knowledge we are developing
pertaining to the sources of arsenic, its effects at the cellular level,
the ways in which it affects the health of mammals like mice and
ultimately, how it causes disease and harmful health outcomes for


The Marine Biological Laboratory



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