Pesticides and metabolites in cassava, eucalyptus, plum and cashew leaves and roots in relation to a point source in Kibaha, Tanzania

Abstract

Leaves of Eucalyptus sp., Prunus domestica (plum), and Anacardium occidentale (cashew), as well as roots and leaves of Manihot esculenta (cassava) were used to study the local distribution of pesticides and metabolites from a point source, an old storage site at Vikuge farm in Tanzania. The GPC-cleaned extracts were analyzed by GC-ECD and GC/MS. Eleven organochlorine pesticide residues namely pentachloroanisole, p, p′-DDT, o, p′-DDT, p, p′-DDE, o, p′-DDE, p, p′-DDD, o, p′-DDD, α-HCH, β-HCH, δ-HCH and ε-HCH were detected in the samples. The concentrations of total DDT were 818 ng/g fw in Eucalyptus sp., 16 ng/g fw in A. occidentale and 4 ng/g fw in P. domestica. In M. esculenta, total DDT ranged from 191 to 586 ng/g fw in roots and 7 to 425 ng/g fw in leaves. The concentrations of total HCH were up to 15 ng/g fw in Eucalyptus sp., while the concentrations of pentachloroanisole were up to 2 ng/g fw in leaves of M. esculenta. There are very strong positive correlations in the concentrations of the detected compounds, suggesting that they have a common source. The low DDE/DDT ratios (0.02–0.07) in all samples indicate input of non-degraded DDT from the source. The high α-HCH/γ-HCH ratios in some samples (>3.1–10) indicate input of technical HCH. The concentrations of total DDT in cassava roots were either very close to, or greater than, the FAO/WHO limit, indicating risks and concern to public health.