By Dr. Iqbal Saeed Khan, Former Director EPA Sindh, Karachi
Dioxins were discovered as undesirable substance while some organochlorine compounds were synthesized and various processes of incineration about thirty years back. Dioxins are one of the most Potent Toxins Chemicals known in Environment, and they are serious public threat much more than D.D.T in previous decade. Dioxin and dioxin like substances are man-made pollutants. Dioxins are of more than 75 types having more or less similar chemical structure, and with slight variation in structure. In cities dioxins are released from improper functioning incinerators. The incinerators are commonly used to burn down the toxic waste but when incinerators are used at lower temperature or old incinerators which are single chambered in which complete burning is less possible due to being older one, the Dioxins are formed un-intentionally as a bye product of many chemical industrial process, particularly waste incineration and if the incinerators are properly operated or if the prescribed temperature is not given to waste in incinerators. Besides, Dioxins are produced in pulp and paper bleaching, pesticides manufacturing, Polythene bags burning in open garbage etc. Open garbage burning which is quite common in our society and if garbage burning contains polythene or allied substances then it leads to dioxins formation in air.
Dioxin is a carcinogen and it is considered by many research groups throughout the world as Group 1 carcinogen.
Dioxins are also blamed to produce reproductive defects and can lead to developmental disorders. They damage immune system of animals and human beings and interfere in normal functions of hormones. Some research authority considers them as an environmental estrogens.
By their nature Dioxins are fat soluble chemical compounds and they accumulate in fatty tissue and do not excrete rather then they bio-accumulate in fatty/adipose tissues and hence its level continue to rise with the passage of time in humans, animals including oceanic animals. Due to this hydrophobic (water repelling) and lipophillic (fat loving nature) it rapidly accumulated in fatty tissue of fish and consequently is locked in food web.
Dioxins are present in air, soil and water if they are contaminated. Men and male animals have virtually no way to excrete them. But in females, it crosses the placenta and goes into growing infants, subsequently it is released in breast milk and cause harm to new borns and infants.
Human subjects are mainly exposed to it in following ways:
- Through diet
- Industrial accident
- Work place contaminates
Mainly dioxin enter the body through the diet having fat of animal origin, however human subjects can also introduce the Dioxin in themselves.
The principal identified sources as available in literature is combustion, incineration, manufacturing and processing of the industrial and municipal process. These compounds are found in all media including air, soil, water sediments, fish, agriculture food products and meat and dairy products etc.
The Dioxins and other Poly Chlorinated bi- phenyls are highly stable in nature and they are included in the list of persistent organic pollutants. As they are not easily soluble in water hence cannot be filtered or very slowly filtered by kidneys of humans and animals. Dioxins and PCBs in air or in soil unlimitedly reach the water bodies, where it is taken up by aquatic animals or by human beings who thrive upon contaminated water. Old electronic transformers where oil circulates for long time, or if over used can lead to formation of such substance because, finally this oil is thrown without any caution in soil or water bodies in non-environmentally friendly manner.
It is now a well known fact that a defoliating agent (chemicals used to remove leaves of tree) was dropped by USA in Vietnam War between 1962 to 1971 to clear the jungles and to hound out the gorillas. However it is proved that the substance was a pesticide of dioxin type and still leading to birth defects in children, with brain disorders and bulging out eyes in Vietnam and in the areas of USA where the substance was prepared the people suffered toxicity.
It is incumbent upon medical professionals and environmentalists to have its knowledge.