What are the health effects of contaminants in drinking water?
EPA has set safety standards for more than 80 contaminants that
may occur in drinking water and pose a risk to human health. We can
put these contaminants into two groups according to the health effects
that they may cause. Acute effects occur within hours or days of
the time that a person consumes a contaminant. Although almost every
contaminant could have an acute effect if consumed at extraordinarily
high levels in drinking water, the contaminants that are most likely
to cause acute effects, if found at high enough levels, are bacteria
and viruses. Most people’s bodies can fight off these microbial contaminants
the way they fight off germs, and these acute contaminants typically
don’t have permanent effects. Nonetheless, they can make people ill,
and can be dangerous or deadly for a person whose immune system is
already weak due to HIV/AIDS, chemotherapy, steroid use, or another
reason.Chronic effects occur after people consume a contaminant at levels
over EPA’s safety standards for many years. The drinking water contaminants
that can have chronic effects are chemicals (such as solvents and
pesticides), radionuclides (such as radium), and minerals (such as
arsenic). Examples of the chronic effects of drinking water contaminants
are cancer, liver or kidney problems, or reproductive difficulties.
What contaminants may be found in drinking water?
There is no such thing as naturally pure water. In nature, all water
contains some impurities. As water flows in streams, sits in lakes,
and filters through layers of soil and rock in the ground, it dissolves
or absorbs the substances that it touches. Some of these substances
are harmless. In fact, some people prefer mineral water precisely
because minerals give it an appealing taste. However, at certain
levels minerals, just like man-made chemicals, are considered contaminants
that can make water unpalatable or even unsafe.Some contaminants come from erosion of natural rock formations.
Other contaminants are substances discharged from factories, applied
to farmlands, or used by consumers in their homes and yards. Sources
of contaminants might be in your neighborhood or might be many miles
away. Your local water quality report tells which contaminants are
in your drinking water, the levels at which they were found, and
the actual or likely source of each contaminant.
Some ground water systems have established wellhead protection programs
to prevent substances from contaminating their wells. Similarly,
some surface water systems protect the watershed around their reservoir
to prevent contamination. Right now, states and water suppliers are
working systematically to assess every source of drinking water and
to identify potential sources of contaminants. This process will
help communities to protect their drinking water supplies from contamination,
and a summary of the results will be in future water quality reports.
