HES4808 Assignment 2 Draft.doc - UNIVERSITY OF SOUTH AFRICA HES4808 ENVIRONMENTAL RISK ASSESSMENT AND MANAGEMENT ASSIGNMENT 02 UNIQUE CODE 586194

HES4808 Assignment 2 Draft.doc - UNIVERSITY OF SOUTH AFRICA...

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UNIVERSITY OF SOUTH AFRICAHES4808ENVIRONMENTAL RISK ASSESSMENT AND MANAGEMENTASSIGNMENT 02UNIQUE CODE: 586194Nosipho MathenjwaStudent no: 51829800Lecturer: Dr M ChitakiraDue date: 19 June 2015Contact details: 076 666 8384[email protected]0
TABLE OF CONTENTSCONTENTSPAGEQuestion 12Question 38References201
QUESTION 1INTRODUCTION AND CHEMICAL BACKGROUNDTechnological and industrial development over the years has caused a release ofseveral anthropogenic chemicals, about a 100 000 of chemicals are registered in theEU however only 14% of their information is available on the public, some of theseare beneficial for health care, agriculture, water and wastewater treatment but sometend to pose a harmful threat to the environment and mankind.Over the past half a century, scientists have uncovered a multitude of risks to wildlifeand humans posed by toxic chemicals. Some of the most notorious chemicals havebeen taken off the market and others have been restricted to a narrower range ofuses. Yet while a handful of these chemicals are slowly disappearing from theenvironment, new research is revealing that many other chemicals could be evenmore harmful than the infamous ones. Wildlife and humans are simultaneouslysuffering contamination by chemicals no longer in production, as well as chemicalscurrently in use, the dangers of which are becoming increasing clear (Brown, 2003). Chemicals are categorised/ grouped according to their sources, this include naturalchemicals and synthetic chemicals which are:Natural ChemicalsNatural chemicals are unprocessed chemicals that exist in nature such as celluloseproduced by plants; they are derived from natural sources including fossil fuels(petroleum, coal) which are products from decay material of plants and animals.Natural chemical contain a range of organic chemical and inorganic chemicals.Organochlorine pesticidesare chlorinated hydrocarbons used extensively from the1940s through the 1960s in agriculture and mosquito control. Representativecompounds in this group include Dichloro Diphenyl Trichloroethane (DDT) andchlorinated alicyclics.DDT was discovered and first synthesised in 1874 by a chemist called Zeidler, it isone of the harmful chemical, affecting the environment and plants. DDT does notoccur naturally in the environment.DDT got its name from an old and imprecise name Dichloro DiphenylTrichloroethaneand was the insecticide to end all insecticides when it came out. Later another2
scientist, Mueller, discovered DDT's insecticidal properties in 1939. DDT is effectiveagainst many organisms, but it is most spectacular success has been in the controlof the Anophelesmosquito, which transmits malaria and typhus, and to controlinsects on agricultural crops. DDT was also widely used during the Second WorldWar to protect the troops and civilians from the spread of malaria, typhus and othervector borne diseases. Growing concern about adverse environmental effects,especially on wild birds, led to severe restrictions and bans in many developed

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