Environmental Engineering Reference
In-Depth Information
1.12 Ocean Pollution and Toxic Chemicals
Everyday vast amounts of toxic chemicals enter our waterways and eventually end
up in our oceans and cause harmful effects to the marine ecosystems. They enter the
oceans in a variety of ways, which include escape into water, soil, and air during
manufacture, use, disposal, accidental leaks and ires in products containing these
chemicals. Once in the environment these chemicals travel great distances and end
up in our oceans and accumulate in the soil.
PCB belong to a family of human made, organic chemicals also known as chlorinated
hydrocarbons. They are used in commercial and industrial products namely in
electrical, heat transfer and hydraulic equipment, as plasticisers in paint, plastics,
and rubber products. Although PCB were banned in the USA in 1979 there are still
products in use which will contain PCB that could leach out. PCB cause cancer, affect
the immune system, the reproductive system, the nervous system and the endocrine
system.
DDT a commonly used pesticide was banned in the USA in 1972. Although DDT is
banned in the USA it is still used in other countries for agriculture and disease-control.
DDT and its break down products: DDE and dichlorodiphenyldichloroethane are
persistent, bioaccumulative, and toxic pollutants. DDT takes more than 15 years to
break down. It has harmful effects on humans and is known to cause damage to the
liver, the nervous system, the reproductive system and can cause liver cancer. Eating
contaminated ish products can cause problems. Infants can be exposed through
breast milk.
PVC ranks third globally in terms of plastics output and consumption (over 33 million
tonnes is produced each year). It is used in a variety of products including: bottles,
packaging, toys, construction materials, bedding, clothing, pipes and furnishings.
It is not biodegradable. During the production of PVC, dioxin, a toxic chemical, is
produced and released. Buried PVC or burnt PVC releases dioxins and hydrochloric
acid into the air, which contributes to acid rain that can contaminate land and water.
Dioxins are fat-soluble so they concentrate in the tissues of humans and others species.
Phthalates are additives widely used in the production of PVC to make it soft and
lexible. They are associated with the risk of cancer and damage to the reproductive
organs, kidneys and liver.
Polybrominated diphenylether (PBDE) is a chemical used in industry as a lame
retardant in plastics, PU foams, fabrics, and other materials. PBDE is toxic and it
accumulates in living organisms. Human exposed to PBDE cause liver toxicity, thyroid
toxicity, and neuro-developmental toxicity.
