Concentrations and human health risk assessment of DDT and its metabolites in free-range and commercial chicken products from KwaZulu-Natal, South Africa

ABSTRACT

Organochlorine pesticides such as dichlorodiphenyltrichloroethane (DDT) have been used in agriculture and for disease control purposes over many decades. Reports suggest that DDT exposure may result in a number of adverse effects in humans. In the KwaZulu-Natal Province of South Africa, DDT is sprayed annually in homes (indoor residual spraying) to control the mosquito vector of malaria. In the northern part of the Province, samples of free-range chicken meat (n = 48) and eggs (n = 13), and commercially produced chicken meat (n = 6) and eggs (n = 11), were collected and analysed. Of the free-range chicken meat samples, 94% (45/48) contained DDTs (ΣDDTs median 6.1 ng/g wet weight [ww], maximum 79.1 ng/g ww). Chicken egg contents were also contaminated (ΣDDTs in free-range eggs median 9544 ng/g ww, maximum 96.666 ng/g ww; and in commercial eggs median 1.3 ng/g ww, maximum 4.6 ng/g ww). The predominant DDT congener detected was p,pʹ-DDE in both free-range meat (>63%) and eggs (>66%), followed by p,pʹ-DDT and then p,pʹ-DDD. Based on estimated daily intake values, calculated human risk ratio (carcinogenic) values were >1 for DDTs detected in both free-range chicken products. Consumption of free-range eggs poses a particularly high health risk.

Graphical Abstract

KEYWORDS:

• Dichlorodiphenyltrichloroe-thane
• chicken
• egg
• human health risk
• KwaZulu-Natal

Acknowledgments

We gratefully acknowledge contacts in the KZN region of South Africa, without whom it would not have been possible to collect samples and perform questionnaires. In particular, thanks to Samwel Menyuka and Nelson Nkwanyana for guiding and interpreting, and Dr Ntantiso at Jozini Agriculture Office. From the KwaZula-Natal Health Department, Bruce Margot, Bheki Owabe, Phineas Zikhali and various guides to health camps facilitated this study greatly. Laboratory assistance given by Takahiro Ichise in Hokkaido University is appreciated. This is contribution number 210 from the NWU-Water Research Group.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported in part by the Leading Program at Hokkaido University, and in part by the Japan Society for the Promotion of Science (JSPS KAKENHI Grant Number 16J02013). Support was also received from Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (No. 16H01779, 24248056, 26304043, 15H0282505 and 15K1221305), the foundation of JSPS Core-to-Core Program (AA Science Platforms) and Bilateral Program, and the Soroptimist Japan Foundation, the Nakajima Foundation and the Sumitomo Foundation Grant for Environmental Research Projects.