What are Some Naturally Occurring Sources of Pollution?
Microorganisms: Bacteria, viruses, parasites and other
microorganisms are sometimes found in water. Shallow wells — those with
water close to ground level — are at most risk. Runoff, or water flowing
over the land surface, may pick up these pollutants from wildlife and
soils. This is often the case after flooding. Some of these organisms
can cause a variety of illnesses. Symptoms include nausea and diarrhea.
These can occur shortly after drinking contaminated water. The effects
could be short-term yet severe (similar to food poisoning) or might recur
frequently or develop slowly over a long time.
Radionuclides: Radionuclides are radioactive elements
such as uranium and radium. They may be present in underlying rock and
ground water. Radon — a gas that is a natural product of the breakdown
of uranium in the soil — can also pose a threat. Radon is most dangerous
when inhaled and contributes to lung cancer. Although soil is the primary
source, using household water containing Radon contributes to elevated
indoor Radon levels. Radon is less dangerous when consumed in water, but
remains a risk to health.
Nitrates and Nitrites: Although high nitrate levels
are usually due to human activities (see below), they may be found naturally
in ground water. They come from the breakdown of nitrogen compounds in
the soil. Flowing ground water picks them up from the soil. Drinking large
amounts of nitrates and nitrites is particularly threatening to infants
(for example, when mixed in formula).
Heavy Metals: Underground rocks and soils may contain
arsenic, cadmium, chromium, lead, and selenium. However, these contaminants
are not often found in household wells at dangerous levels from natural
sources.
Fluoride: Fluoride is helpful in dental health, so many
water systems add small amounts to drinking water. However, excessive
consumption of naturally occurring fluoride can damage bone tissue. High
levels of fluoride occur naturally in some areas. It may discolor teeth,
but this is not a health risk.
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