The prospects in Malaya in the immediate future may be briefly summarized as follows : For residual sprays, DDT and gamma BHC, unless some outstanding new compound appears, will continue to be the most widely used. Both kill the principal malaria carrier. Anopheles maculatus and gamma BHC for a short period after application also kills the common nuisance mosquito, Culex fatigans. Though DDT does not kill C fatigans it prevents them from resting in rooms and reduces the number of biting. Both insecticides should eliminate bed bugs Cimex hemipterus during the course of spraying and reduce cockroach infestation. For the elimination of cockroaches and ants from houses gamma BHC is superior to DDT but the effect is short lived. The other residual insecticides, Chlordane, Toxaphene, Methoxychlor and the newer products Aldrin and Dieldrin are not likely to be used extensively in Malaya. They cannot yet be purchased locally and on present indications have no outstanding advantages to recommend them instead of DDT or BHC. Personal protection against scrub typhus infection is now satisfactory. Either DBP or benzyl benzoate rubbed into clothing should prevent the attachment of mites for several days, and DMP is also effective if applied daily to the skin or clothing. The mite population in an infective area can probably be reduced effectively by spraying BHC on the vegetation, but this method of control is not likely to be attempted in many areas. DMP is a good mosquito repellent and forms the main ingredient of several commercial preparations; it is not as effective when incorpora ted in a cream as it is when pure. Of the several simple, efficient remedies now available for head louse and scabies control, gamma BHC in coconut oil is probably the most useful because of its cheapness, ease of application, and effect on both parasites.
The use of ‘Gammexane’ P 520 as a practical larvicide is briefly described. A suitable rate of application is indicated, and the need to train spray operators and supervisors is indicated. Results suggest that the cost of this larvicide for routine control is likely to be one third or less that of oil.
A pioneering study employed a holistic geostatistical approach to predict the spatial variability of a non sampled area in the Chenab River, Pakistan, using kriging interpolation for organochlorine pesticide (OCP)-polluted risk zones. The Present research intended to investigate the carcinogenic and non-carcinogenic human health risks, contamination levels, and spatial variation of OCPs in the Chenab River, Pakistan. The residual OCP content in sediment samples (n = 120) ranged from 0.056 to 32.14 ng/g. DDE and α-HCH were prevalent among all the samples analyzed, with mean concentrations of 15.84 ± 8.02 and 12.45 ± 6.72 ng/g, respectively. The order of magnitude of OCPs in sediment samples was DDTs > α-HCH > chlorothalonil > heptachlor > endosulfan > aldrin > dieldrin. The findings of the single (SPI) and Nemerow (Nel) pollution index of α-HCH, heptachlor, and aldrin depicted the Chenab River as a serious pollution risk zone. The outcomes of the Pearson correlation coefficient analysis represent the positive correlation among all OCPs, revealing the common origin. Distribution trends showed substantially higher (p 10-4 illustrated a substantial cancer health risk posed by α-HCH, heptachlor, aldrin, and dieldrin in the downstream zone. We recommend the urgent cessation of the ongoing discharge of OCPs into the Chenab River, which needs to be highlighted owing to the significant cancer risk to public health to ensure the good health and wellbeings.
1. Several experiments were carried out in the field and in the laboratory with various insecticides against A maculatus. 2. Almost all the mosquitoes that came into contact with surfaces sprayed with DDT preparations died in less than 30 hours but the length of life varied with the preparation and depended on various factors that are mentioned. Control mosquitoes lived almost twice as long. 3. Gammexane Dispersible Powder (P 520) killed in a much shorter time than the DDT preparations and holds out a greater hope of success in controlling ‘A maculatus’ malaria with insecticides. 4. It is difficult to assess the value of insecticides in any one year in areas where breeding of the vector is intense. The results of long term field experiments, under strict control, are awaited. 5. Meanwhile, Mass Suppression with drugs still remains the method of choice – in this area.
Plastic resin pellets collected at Minh Chau island and Ba Lat estuary between 2007 and 2014 in Vietnam were analyzed for dichloro-diphenyl-trichloroethanes (DDTs), polychlorinated biphenyls (PCBs) and hexachlorocyclohexanes (HCHs). The study was carried out as part of the International Pellet Watch program for monitoring the global distribution of persistent organic pollutants (POPs). Higher levels of DDTs compared to PCBs indicated agricultural inputs rather than industrial discharges in the region. Most POP concentrations on both beaches decreased over the period, with the exception of HCH isomers. Though the concentration of DDTs showed a drastic decline on both beaches between 2007/2008 and 2014, DDTs accounted for 60-80% of total DDTs, suggesting that there is still a fresh input of these chemicals in the region. This study strongly recommends further investigations to track temporal and spatial patterns of POP levels in the marine environment using plastic resin pellets.
Contamination of persistent organochlorines (OCs) such as PCBs (polychlorinated biphenyls), DDT and its metabolites (DDTs), HCH (hexachlorocyclohexane) isomers (HCHs), chlordane compounds (CHLs), and HCB (hexachlorobenzene) were examined in mussels collected from coastal waters of Asian countries such as Cambodia, China, Hong Kong, India, Indonesia, Japan, Korea, Malaysia, Philippines, Far East Russia, Singapore, and Vietnam in 1994, 1997, 1998, 1999, and 2001 to elucidate the contamination status, distribution and possible pollution sources and to assess the risks on aquatic organisms and human. OCs were detected in all mussels collected from all the sampling sites investigated. Considerable residue levels of p,p(')-DDT and alpha-HCH were found in mussels and the concentrations of DDTs and HCHs found in mussels from Asian developing countries were higher than those in developed nations suggesting present usage of DDTs and HCHs along the coastal waters of Asian developing countries. On the other hand, lower concentrations of PCBs detected in mussels from Asian developing countries than those in developed countries indicate that PCBs contamination in mussels is strongly related to industrial and activities. To our knowledge, this is a first comprehensive report on monitoring OCs pollution in the Asia-Pacific region.
A study was carried out in theJengka Triangle in Pahang to find out the prevalence and a practical cum effective method of treatment and control of scabies. Scabies was the commonest skin lesion among the 5590 people examined. its prevalence being 11.6%. Both sexes were equally affected. Prevalence was high among children and teenagers, the worst affected being the 10 to 14. 2 to 4, 15 to 19 and 5 to 9 year olds. The problem of scabies in Jengka could be due to inadequate and irregular water supply, plus lack of mothers' supervision of the personal hygiene of their children aged > 2 years. The persistence of scabies since 1976 is very likely due to the people's non-compliance with standing instructions on treatment with Benzyl benzoate emulsion A comparative study of treatment of scabies with Gamma Benzene Hexachloride [GBH] and with Benzyl benzoate emulsion [BBE] showed GBH to be the medication of choice. It was more effective and convenient, giving 97.9% cure rate with one application. A hot bath was not necessary. The patients preferred GBH to BBE since it was painless and without side-effects. The cost of treatment with GBH [1 application] was also much less than that with BBE [2 applications]. Only 28.7% of the cases and contacts complied with instructions to do 2nd application of the medication on their own, making it imperative that application be done by the health Staff or under their direct supervision. The majority [87.2%] complied with instructions to place their used clothes in large polythene bags and air these in the sun for two days. This procedure should replace the instructions to boil personal clothes as it is just as effective. yet more convenient and economical. A regular, biannual screening of all kindergarten and primary school children is recommended. Application of GBH to all scabies cases and all close contacts should be done by the health worker. The whole body from neck to soles of feet should have the application, and the people should be instructed to bathe only after 24 hours. They are to go to the nearest clinic or hospital on the 7th day for second application of GBH, if the itchness or lesions persist or reappear. Such supervised medication is possible and will minimise misuse of GBH.
A total of seven pesticides and eight alkylphenols were monitored using this method for the determination of their trace levels in human cord blood. The pesticides are lindane, diazinon, alpha-endosulfan, beta-endosulfan, endosulfan sulfate, chlorpyrifos and endrin; while the alkylphenols are 4-n-butylphenol, 4-n-pentylphenol, 4-n-hexylphenol, 4-t-octylphenol, 4-n-heptylphenol, nonylphenol, 4-n-octylphenol and bisphenol A. The pesticides and alkylphenols in the cord blood samples were extracted with solid phase extraction IST C18 cartridges and analyzed by selected ion monitoring mode using quadrapole detector in Shimadzu QP-5000 gas chromatograph-mass spectrometer. Trace levels of pesticide and alkylphenols in the range of non-detectable to 15.17 ng ml(-1), were detected in the human cord blood samples. This technique of monitoring the levels of endocrine-disruptors in blood samples is consistent, reliable and cost effective while reducing wastage of time and solvents.
Insecticides Abate, DDT, Dowco-214, Dursban, fenitrothion, fenthion, gamma-HCH, and malathion were tested against the field collected fourth instars larvae of Mansonia from Penang Island, Malaysia. The larvae appeared to be highly susceptible to Dursban and Abate with LC50 values of 1.54 and 1.92 parts per billion respectively. Other chemicals, in decreasing degree of effectiveness, were gamma-HCH, fenthion, P,P'-DDT, Dowco-214, fenithrothion and malathion. The potential use of these chemicals in Mansonia control was discussed. A simple method for collecting and testing Mansonia larvae was also described.
In this paper, we concisely reviewed the contamination of persistent organic pollutants (POPs) such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) in human breast milk collected from Asian countries such as Japan, China, Philippines, Vietnam, Cambodia, India, Malaysia, and Indonesia during 1999-2003. Dioxins, PCBs, CHLs in Japanese, and DDTs in Vietnamese, Chinese, Cambodian, Malaysian, and HCHs in Chinese, Indian, and HCB in Chinese breast milk were predominant. In India, levels of dioxins and related compounds (DRCs) in the mothers living around the open dumping site were notably higher than those from the reference site and other Asian developing countries, indicating that significant pollution sources of DRCs are present in the dumping site of India and the residents there have been exposed to relatively higher levels of these contaminants possibly via bovine milk.
Some insecticides to control and prevent screw-worm fly strike by Chrysomya bezziana in calves and adult cattle were tested in field trials on cattle in Sabah, East Malaysia. Ivermectin injected subcutaneously in newborn calves at 200 mu/kg provided 10 days protection from screw-worm fly strike, which allowed navels to dry. Ivermectin, 1% dichlofenthion plus gentian violet and 3% lindane plus pine oil smear were all effective in preventing re-strike of treated wounds in adult cattle. A single subcutaneous injection of ivermectin at 200 mu/kg was effective, whereas it was necessary to re-apply the dichlofenthion and lindane smear preparations every 48h.
Persistent organochlorines in air, river water and sediment samples were analysed from eastern and southern Asia (India, Thailand, Vietnam, Malaysia, Indonesia) and Oceania (Papua New Guinea and Solomon Islands) to elucidate their geographical distribution in tropical environment. The concentrations of organochlorines in these abiotic samples collected from Taiwan, Japan and Australia were also monitored for comparison. Atmospheric and hydrospheric concentrations of HCHs (hexachlorocyclohexanes) and DDTs (DDT and its metabolites) in the tropical developing countries were apparently higher than those observed in the developed nations, suggesting extensive usage of these chemicals in the lower latitudes. CHLs (chlordane compounds) and PCBs (polychlorinated biphenyls) were also occasionally observed at higher levels in the tropics, implying that their usage area is also expanding southward. Distribution patterns of organochlorines in sediments showed smaller spatial variations on global terms, indicating that the chemicals released in the tropical environment are dispersed rapidly through air and water and retained less in sediments. The ratios of organochlorine concentrations in sediment and water phases were positively correlated with the latitude of sampling, suggesting that persistent and semivolatile compounds discharged in the tropics tend to be redistributed on a global scale.