An assessment of the extent of bovine milk pollution by DDT used in public
Health in Zimbabwe

Gerome Brock, Sanele Mnkandla, *Norah Basopo
Page No. 16-22

Indoor residual spraying of dichlorodiphenyltrichloroethane (DDT) has been widely used in the
control of malaria, and has been appreciated for its low cost and high effectiveness. Prolonged use,
however, has adverse effects as DDT and its metabolites persist for long in the environment,
resulting in human and animal contamination. Contamination in animals such as cattle may result
from consuming contaminated water, feed and fodder. The aim of the study was to evaluate the
extent of contamination of DDT and its metabolites in cow’s milk from five towns in Zimbabwe.
Samples were collected from farms around Bulawayo, Chiredzi, Esigodini, Harare and Mutare with
a total of n=24 samples. The pesticide residues were extracted using the quick, easy, cheap, rugged
and safe (Quechers®) method and solid phase extraction and analysed using gas chromatography
with electron capture detector. Total DDT was detected in all samples at levels higher than the
maximum allowable residue limit. Harare and Mutare samples had the highest DDT levels of 0.38
μg/ml and 0.26 μg/ml respectively, as compared with samples from other regions (0.08-0.13 μg/ml).
The DDT metabolite residues,1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) and 1,1-dichloro-
2,2-bis(p-dichlorodiphenyl)ethylene (DDE), were also detected at varying levels in the samples. The
results show the presence of DDT and its metabolite contaminants in bovine milk, posing a serious
health risk to consumers. Alternatives to DDT may therefore need to be employed in the control of
the malaria vector.