Assessment of DDT contamination in house rat as a possible bioindicator in DDT-sprayed areas from Ethiopia and South Africa
Ethiopia and South Africa are among the few countries to still implement indoor residual spraying with dichloro-diphenyl-trichloroethane (DDT) for malaria vector control. In this study, we investigated the levels and ecological risks of DDT and its metabolites in liver tissues of house rat, as a sentinel animal, for providing an early warning system for public health and wildlife intervention from Ethiopia and South Africa. The results showed that ΣDDT concentration ranged from 127 to 9155 μg/kg wet weight, and the distribution order of DDT and its metabolites in the analyzed liver samples was p,p′-DDD > p,p′-DDE >> p,p′-DDT, o,p′-DDT, and o,p′-DDD. The risk assessment indicated a potential adverse impact on humans, especially for pregnant women and children, because they spend majority of their time in a DDT-sprayed house. The ecological assessment also showed a concern for birds of prey and amphibians like frogs. This study is the first report on DDT contamination in liver tissues of house rats from Ethiopia and South Africa, and henceforth, the data will serve as a reference data for future studies.
KeywordsDDT House rat Liver Risk assessment Ethiopia South Africa
This work was supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan awarded to M. Ishizuka (no. 16H0177906), Y. Ikenaka (no. 26304043, 15H0282505, 15K1221305), S. Nakayama (16K16197), and the foundations of JSPS Core to Core Program (AA Science Platforms) and the Bilateral Joint Research Project (PG36150002 and PG36150003). We also acknowledge the financial support by the Mitsui & Co., Ltd. Environment Fund; the Sumitomo foundation for Environmental Research Projects; the Soroptimist Japan Foundation; the Nakajima Foundation; and the Inui Memorial Trust for Research on Animal Science. The authors are grateful to thank the local people for allowing us to catch the house rats and Mr. Takahiro Ichise, Ms. Mio Yagihashi, and Ms. Nagisa Hirano for their technical support and great input throughout the research work.
Compliance with ethical standards
All the experiments were performed in accordance with the guidelines approved by the Institutional Animal Care and Use Committee of Hokkaido University.
Conflict of interest
The authors declare that they have no conflict of interest.
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