The efficacy of two formulations, wettable powder and emulsifiable concentrate, of cyfluthrin sprayed on plywood [10 mg (ai)/m2] was assessed against six species of mosquitos. The bioassay followed the WHO standard method, with some modification for the bioassay of insecticidal deposits on wall surfaces. The results indicated that these two formulations of cyfluthrin were effective against Anopheles dirus and Mansonia uniformis, moderately toxic to Aedes aegypti and Ae. albopictus in decreasing mortality through out the study period. It was least effective against Culex quinquefasciatus and An. maculatus, respectively. There was no statistically significant difference between these two formulations.
This study determined the concentrations of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides, and tris(4-chlorophenyl) methane (TCPMe) in human breast milk samples collected in 2003 from primipara mothers living in Penang, Malaysia. OCs were detected in all the samples analyzed with DDTs, hexachlorocyclohexane isomers (HCHs), and PCBs as the major contaminants followed by chlordane compounds (CHLs), hexachlorobenzene (HCB), and TCPMe. The residue levels of DDTs, HCHs, and CHLs were comparable to or higher than those in general populations of other countries, whereas PCBs and HCB were relatively low. In addition, dioxins and related compounds were also detected with a range of dioxin equivalent concentrations from 3.4 to 24 pg-TEQs/g lipid wt. Levels of toxic equivalents (TEQs) were slightly higher than those in other developing countries but still much lower than those of industrialized nations. One donor mother contained a high TEQs level, equal to the mean value in human breast milk from Japan, implying that some of the residents in Malaysia may be exposed to specific pollution sources of dioxins and related compounds. No association was observed between OCs concentrations and maternal characteristics, which might be related to a limited number of samples, narrow range of age of the donor mothers, and/or other external factors. The recently identified endocrine disrupter, TCPMe, was also detected in all human breast milk samples of this study. A significant positive correlation was observed between TCPMe and DDTs, suggesting that technical DDT might be a source of TCPMe in Malaysia. The present study provides a useful baseline for future studies on the accumulations of OCs in the general population of Malaysia.