Organophosphate and Carbamate Pesticide Residues in Beans from Markets in Lagos State, Nigeria

Abstract

Foods treated with pesticides for protection against destructive pests often
contain residues of these chemicals. The levels of pesticide residues in food are often
determined as a means of assessing appropriate use as well as the level of human exposure
to these chemicals and hence their potential human health hazards. The aim of this study
was to determine the concentration of organophosphate and carbamate pesticides in beans
samples collected from markets in Lagos State and compare these values with established
safety values. Beans (Phaseolus vulgaris L.) samples purchased from different markets in
Lagos State were analyzed for residues of organophosphate and carbamate pesticides.
Analysis was done using gas chromatograph with mass spectrometric detector (GC-MS)
after careful extraction and cleanup. It was found that all the beans samples contained
residues of one or more organophosphate or carbamate pesticides. Mean concentrations
ranged from 19.4 to 455.9 µg/kg. Maximum residue limits (MRL) of the various pesticides
(except for parathion) were exceeded in up to 10% of samples. The estimated total diet
intake (ETDI) for dichlorvos exceeded its maximum permissible intake (MPI) by 131%.
Organophosphate and carbamate pesticide residues are present in beans sold in Lagos
markets and maximum residue limits for most of the pesticides are exceeded. There is
therefore a need for more stringent monitoring of importation and use of these pesticides in
agriculture and food storage in Nigeria.