The Impact of Pesticides - Academy Publish

fed for a lifespan at 5-1,600 mg/kg diet with a mean age at death of 58 weeks, hadno increase in tumor incidence. One of the confounding factors in establishing a linkbetween the insecticide and carcinogenicity is the presence of three differentdimensional forms of HCH isomers. Each form has a slightly different toxicity. TheInternational Agency for Research on Cancer has concluded that there is sufficientevidence to show that one of the lindane isomers is carcinogenic and limitedevidence to establish the carcinogenicity of the beta and gamma isomers.Female rats experienced a disturbance of their reproductive cycle and inhibitedfertility with doses of 0.5 mg/kg for four months. Treatments of 0.05 mg/kg did notproduce these effects. Lindane was found to be slightly estrogenic to female rats andalso caused the seminiferous tubules in male rats to become atrophied at doses of 8mg/kg/day over a ten day period. These tests suggest that the compound may havereproductive effects in human populations.Beagles given 7.5 or 15 mg/kg from day five throughout gestation did not producepups with any noticeable birth defects. Pregnant rats given small amounts of lindanein their food had offspring unaffected by the pesticide. Lindane, however, can bepassed from the mother to the developing fetus. It appears that lindane will notcause developmental effects at low levels of exposure and causes reproductiveeffects at levels approaching the acute toxicity doses. These effects have not beenobserved in human populations.A variety of tests on mice and on microbes have shown no mutagenicity in the cellstested. It has been shown to induce some changes in the chromosomes of culturedhuman lymphocytes during cell division at fairly low doses. It is unlikely thatlindane would pose a mutagenic risk in humans at very low exposure levels(ATSDR, 2005).Current situation of study compounds in VietnamCurrent applicationDDT usages for malaria control in Vietnam begun in 1954 and officially ended in1995. Before 1993, DDT was even sprayed onto the walls for mosquito preventionin malaria prevention programs. From 1962 to 1981, DDT was widely used in greatamounts. Basing on World Bank’s documents, in 1962, 1963 and 1981, the amountof DDT for health service reached 1000 tonnes annually (Buxton et al., 2001). In1990, malaria broke out in large scale, therefore the import of DDT into Viet Namincreased considerably from 1992. DDT was also used for malaria control duringthe time of war. It is estimated that Vietnam imported approximately 447 tonnes ofDDT for malaria control purpose.DDT and HCH were once used as pesticides in large amounts. Since 1995, DDTand HCH were wide applied for soil treatment before cultivations, harmful insectprevention and farm product preservation after harvest. At present, the official banon DDT, HCH import and usage is in place. However, there are still high risks ofillegal import of these substances in the border between Vietnam and China.AcademyPublish.org - The Impact of Pesticides296