Question

What are chemicals? List three chemicals and explain how they may be beneficial or detrimental to humans or the environment.

Answer 1

chemical is a substance obtained by or used in a chemical process; a chemical compound.

3 chemicals and their effect on humans or environment are as follows-

1) Organochlorines

Organochlorine compounds such as polychlorinated biphenyls or PCBs were developed originally for use in electric equipment as cooling agents and are very dangerous chemicals. They are nearly indestructible and large quantities remain in existence and they will remain in the environment for a long time. They accumulate in the food chain and significant levels of them have been found in marine species, particularly mammals and sea birds, decades after their production was discontinued. They are carcinogenic and capable of damaging the liver, nervous system and the reproductive system in adults. When PCBs are burned, even more toxic dioxins are formed.

2) Dioxins

Dioxins, are a class of super-toxic chemicals formed as a by-product of the manufacture, moulding, or burning of organic chemicals and plastics that contain chlorine. They are the most toxic man-made organic chemicals known. They cause serious health effects even at levels as low as a few parts per trillion. Only radioactive waste is more toxic. They are virtually indestructible and are excreted by the body extremely slowly. Dioxins enter the body in food and accumulate in body fat. They bind to cell receptors and disrupt hormone functions in the body and they also affect gene functions. Our bodies have no defence against dioxins which may cause a wide range of problems, from cancer to reduced immunity to nervous system disorders to miscarriages and birth deformity. The effects can be very obvious or subtle. Because they change gene functions, they can cause genetic diseases to appear and they can interfere with child development. Attention Deficit Disorder, diabetes, endometriosis, chronic fatigue syndrome, rare nervous and blood disorders have been linked to exposure to dioxins and PCBs.

3) Cadmium

Cadmium occurs naturally in the earth's crust combined with other elements. It is usually formed as a mineral such as cadmium oxide, cadmium chloride, or cadmium sulphate and although these compounds are highly toxic they are less harmful when bound to rocks. They are present in coal and in the soil.

Cadmium is useful because it doesn't corrode easily. It is used in batteries, plastics, pigments and metal coatings. Cadmium particles enter our air when we burn coal for energy and incinerate household waste. The particles can travel far before falling to the ground or water. Each year many tonnes of cadmium are discharged into our seas and oceans. Animals and plants take up cadmium when it is in the environment. If we consume food contaminated with cadmium it can irritate our digestive system and cause vomiting and diarrhoea. If inhaled it can damage our lungs. Even when levels of exposure are low, over time, cadmium accumulates in the body and it can be difficult to get rid of. Accumulated cadmium can cause kidneys and bone disease.