Which toxic
chemicals in Puget Sound are most dangerous? This isn’t an easy
question to answer since different chemicals cause harm in different
ways and to different organisms. The hazard any given chemical poses
depends on how toxic it is and how much enters the Puget Sound
environment.
Some toxic chemicals don’t break down easily in the environment, and
they can move up through the food chain. These “persistent,
bioaccumulative” toxic chemicals can build up in the tissues of
small organisms living in Puget Sound. These tiny living things are
eaten by fish, which in turn are then eaten by larger fish, marine
mammals, and sometimes humans – harming their health.
Recent studies by NOAA Fisheries and the U.S. Fish and Wildlife
Service have found that Coho salmon are dying prematurely in large
numbers when they return from the ocean to spawn in Puget Sound’s
urban streams. Although the precise cause of these die-offs is not
yet known, toxic chemicals in polluted surface water runoff likely
play a role.
Research has identified the following specific harmful effects of
toxic chemicals:
Arsenic
Arsenic and many of its compounds are especially potent poisons.
Many water supplies close to mines are contaminated by these
poisons. Arsenic causes harm by disrupting metabolism at the
cellular level. Arsenic can cause fetal death and malformations in
many mammal species.
Cadmium
Cadmium can be acutely toxic to freshwater organisms. While marine
organisms are more resistant to cadmium, shellfish can concentrate
cadmium in levels that are harmful to people who eat them.
Copper
Copper is a special concern. While people may not be harmed by small
amounts of copper, even low levels of the chemical are a significant
threat to salmon and other fish in Puget Sound. Copper interferes
with salmon’s sense of smell, which reduces their ability to avoid
predators, find their way back to their birthplace to spawn, and
find mates.
Lead
Lead is a natural element in the environment but most lead-related
health and environmental problems are the result of human
activities. Lead is present in Puget Sound from past uses such as
when lead was added to gasoline, household products like ammunition,
and uses in some occupations like specialty glass manufacturing.
Lead is a known persistent bioaccumulative toxic chemical which
means past uses can continue to expose people and other organisms.
Lead can impair brain development and learning in children and can
affect behavior, high blood pressure, reproduction, and growth in
both children and adults. Lead similarly affects animal species.
Waterfowl are particularly at risk to lead shot if they ingest it
while feeding.
Mercury
Mercury is very toxic. It is mostly known as a neurotoxin, meaning
that it harms the brain and nervous system. However, mercury is also
linked to kidney and liver damage and possibly cancer. Children are
especially at risk because of their brains and bodies are still
developing. Many of the health effects of mercury can be permanent.
When it rains, airborne mercury deposits back on the land and water
bodies that drain to Puget Sound. Some of the mercury is converted
into methyl mercury, a highly stable compound that contaminates our
water and our marine life. The methyl mercury concentrates up the
food chain, especially in certain fish where it can affect the
health of people who eat them. Infants, children and pregnant or
nursing mothers must take special precautions to minimize mercury
exposure from fish.
Zinc
Zinc can kill young salmon as they swim out of their nest gravel. In
high enough concentrations, zinc can kill many adult fish species.
PAHs (polycyclic aromatic hydrocarbons)
PAHs in the bottom sediments of Puget Sound can cause tumors in
marine flatfish. PAHs from oil and fuel spills in water can cause
heart defects in the developing embryos of herring and other fish
species.
Petroleum-related compounds
Petroleum-related compounds – including gasoline, motor oil,
hydraulic fluids, diesel and jet fuels – are mixtures of many
different chemicals, including additives. Many petrochemicals are
toxic to algae and invertebrates. They can cause changes in
metabolism, reduced feeding, and poor shell formation. These
compounds can poison fish at all life stages and kill their eggs and
larva. They can damage the skin, lungs, liver, and kidneys of birds
and mammals as well as increase vulnerability to deadly infections
by suppressing the immune system. Petrochemicals can reduce the
reproductive success of invertebrates such as shellfish and insects,
fish, birds, and mammals, leading to population declines. They can
also damage plants and impair or stop seed germination.
PBDE flame retardants (polybrominated diphenyl ethers)
PBDE flame retardants can affect the development, reproduction, and
survival of many species. They build up in the food chain and are
found in people as well other organisms including fish and orcas in
Puget Sound.
Phthalates (including DEHP or bis(2-ethylhexyl) phthalate)
Exposure to DEHP, a phthalate, is associated with developmental and
reproductive harm, especially the male reproductive system in humans
and animals.
PCBs (polychlorinated biphenyls)
PCBs build up in the food chain and can cause adverse health effects
in humans and wildlife, including cancer and harm to immune,
nervous, and reproductive systems. PCBs disrupt thyroid hormone
levels in animals and humans, hindering growth and development.
DDT (dichlorodiphenyltrichloroethane)
The pesticide DDT builds up in the food chain and can last for
decades in the environment. DDT is linked to the decline of the bald
eagle, peregrine falcon, and other birds because it makes their egg
shells too thin, decreasing the survival of chicks.
PCDD/Fs dioxins (polychlorinated dibenzo-p-dioxins and
polychlorinated dibenzofurans)
Even at very low concentrations, PCDD/F dioxins are toxic to humans
and animals. Dioxins can cause cancer, disrupt the endocrine
(hormone) system, and harm reproduction and development. While birds
and mammals are at greater risk than fish, dioxins build up in the
food chain and may affect people and animals that eat fish
Triclopyr
In the waters draining to Puget Sound, levels of the weed killer
triclopyr are typically below concentrations where they cause
environmental harm. If misapplied, however, triclopyr can harm fish
and other aquatic species.
Nonylphenol
Nonylphenol, a chemical found in detergents, is thought to mimic
estrogen compounds, reducing reproduction in aquatic organisms.
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