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

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.