Bibliography: leaves 177-191.

Bibliography: leaves 177-191. / xxi, 191 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2001

Thesis (MPhil)--Stellenbosch University, 2003. / Full text to be digitised and attached to bibliographic record. / ENGLISH ABSTRACT: This assignment is devoted to an in depth analysis of the pro- and the contra-positions in the long-standing and costly debate about the question whether to spray with DDT or not in the fight against malaria. I argue that the dilemma whether or not to spray with DDT is born out of a political agenda, hype, exaggeration and misinformation of the first order. Radical environmentalists appear to insist that DDT is a principal contributor of environmental degradation, and the major cause of death amongst wildlife and humans. Worse still, many Western people seem to be under the impression that mosquitoes cannot cause so much human misery as purported, and that malaria is caused by some kind of plant form of life, or even a virus. The proponents of DDT, on the other hand, appear to be convinced that DDT is a saviour of humankind, and argue that the horrors associated with DDT are exaggerated and baseless, as they are not backed by scientific inquiry. Proponents of DDT also believe that anything that is overused may kill, even ordinary table salt. Inthis assignment, both of these positions are scrutinized. On the basis of an historical overview in Chapter I of the history of the use of DDT, and the emergence of the debate about DDT in the wake of Rachel Carson's Silent Spring (1962), Chapter 2 is devoted to an evaluation of seven basic arguments against the use of DDT, while in Chapter 3 six arguments for the use of DDT are weighed. In Chapter 4 a resolution of the dilemma is proposed in which a case is made for a limited use of DDT only for indoor spraying of huts and houses against malaria mosquitoes until such time as a less dangerous alternative for DDT is found that can be used as effectively in the fight against malaria. As such, this case is informed by the strong moral conviction that we cannot allow poor people of colour to die because of a general ban on the use of DDT. Further research on this ethical debate is encouraged. / AFRIKAANSE OPSOMMING: Hierdie werkstuk is toegespits op 'n in-diepte analise van die pro- en kontra-posisies in die voortslepende, asook duur debat oor die gebruik van DDT al dan nie in die bekamping van Malaria. Ek argumenteer dat die dilemma rondom die vraag of DDT gebruik moet word of nie, aangewakker word deur politieke agendas, sensasie, oordrywing en foutiewe informasie van die eerste orde. Radikale omgewingsgesindes dring oënskynlik daarop aan dat die gebruik van DDT 'n hoof-oorsaak is van die agteruitgang van die omgewing, asook 'n primêre oorsaak van dood onder wild en mense. Erger nog, dit wil voorkom of heelwat Westerse mense onder die indruk is dat muskiete nie werklik soveel menslike lyding kan veroorsaak as wat voorgegee word nie, en dat malaria eerder veroorsaak word deur 'n sekere soort plantvorm van lewe, of selfs deur 'n virus. Die voorstaanders van DDT, aan die ander kant, is klaarblyklik oortuig dat DDT 'n redder van die mensdom is, en argumenteer dat die gruwels wat geassosieer word met DDT 'n grondelose oordrywing is, aangesien dit nie deur wetenskaplike ondersoek gesteun word nie. Voorstaanders van DDT glo verder dat enige stof wat in oormaat gebruik word, die dood kan veroorsaak, selfs gewone tafelsout. In hierdie werkstuk word albei hierdie posisies krities bestudeer en bespreek. Op grond van 'n historiese oorsig in Hoofstuk 1 oor die gebruik van DDT, en die ontstaan van die debat oor DDT na aanleiding van Rachel Carson se Silent Spring (1962), word Hoofstuk: 2 gewy aan 'n evaluasie van sewe basiese argumente teen die gebruik van DDT, terwyl in Hoofstuk 3 ses argumente vir die gebruik van DDT oorweeg word. In Hoofstuk 4 word 'n voorstel gemaak vir die resolusie van die dilemma deur 'n saak uit te maak vir die beperkte gebruik van DDT, nl. slegs vir binneshuise gebruik in hutte en huise teen malaria-muskiete tot tyd en wyl 'n minder gevaarlike alternatief vir DDT gevind word wat net so effektief sal wees in die stryd teen malaria. As sulks word hierdie studie gerugsteun deur die sterk morele oortuiging dat ons nie kan toelaat dat mense van kleur sterf as gevolg van 'n algemene verbod op die gebruik van DDT nie. Verdere navorsing oor hierdie etiese debat word aangemoedig.

This thesis presents a first ever extensive analysis of pesticides in water and sediments from the Okavango Delta, Botswana, employing green sample preparation techniques that require small volumes of organic solvents hence generating negligible volumes of organic solvent waste. Pesticides were extracted and pre-concentrated from water by solid phase extraction (SPE) and headspace solid phase microextraction (HS-SPME) while supercritical fluid extraction (SFE) and pressurized fluid extraction (PFE) were employed for sediments. Subsequent analysis was carried out on a gas chromatograph with electron capture detection and analytes were unequivocally confirmed by high resolution mass spectrometric detection. Hexachlorobenzene (HCB), trans-chlordane, 4,4′-DDD and 4,4′-DDE were detected after optimized HS-SPME in several water samples from the lower Delta at concentrations ranging from 2.4 to 61.4 μg L-1 that are much higher than the 0.1 μg L-1 maximum limit of individual organochlorine pesticides in drinking water set by the European Community Directive. The same samples were cleaned with ISOLUTE C18 SPE sorbent with an optimal acetone/n-hexane (1:1 v/v) mixture for the elution of analytes. No pesticides were detected after SPE clean-up and pre-concentration. HCB, aldrin and 4, 4‟-DDT were identified in sediments after SFE at concentration ranges of 1.1 - 30.3, 0.5 – 15.2 and 1.4 – 55.4 μg/g, respectively. There was an increase of pesticides concentrations in the direction of water flow from the Panhandle (point of entry) to the lower delta. DDE, fatty acids and phthalates were detected after PFE with optimized extraction solvent and temperature. The presence of DDT metabolites in the water and sediments from the Okavango Delta confirm historical exposure to the pesticide. However their cumulative concentration increase in the water-flow direction calls for further investigation of point sources for the long-term preservation of the Delta. The green sample preparation techniques and low toxicity solvents employed in this thesis are thus recommended for routine environmental monitoring exercises.