Affiliations: Department of Biology, Eastern Mennonite University,
Harrisonburg, Virginia, USA | Department of Chemistry, Royal University of Phnom
Penh, Cambodia | Department of Chemistry, Eastern Mennonite University,
Harrisonburg, Virginia, USA | Department of Chemistry, Buffalo State College, Buffalo, New York, USA
Abstract: The prevalence of pesticide residue contamination in market
vegetables, and the rate of pesticide disappearance from field vegetables, were
assessed as indicators of the health risk to vegetable consumers in Cambodia. A
total of 245 leafy vegetable and long bean samples from multiple markets in
Phnom Penh were screened using cholinesterase-inhibition assays, and indicated
that between 15% (long bean) and 95% (white-stemmed kale) of market vegetables
contain detectable levels of organophosphate/carbamate (OP/C) pesticides. OP/C
levels varied significantly between vegetable types, and between individual
vegetable sellers in the markets. Methylparathion, which is banned and highly
toxic, but widely used in Cambodia, was not detected in 30 subsamples analyzed
with HPLC. In test plots, methylparathion rapidly disappeared after spraying,
reaching levels below maximum residue limits within 10 days. Field trials with
water spinach indicated dithiocarbamates also have a short half-life
(approximately three days), but that overall OP/C levels on crops depend on the
specific pesticides used, and on the specific field conditions. These results
point towards the need for a regular monitoring programme in Cambodia to assess
the extent of pesticide contamination on vegetables, and to give guidance on
strategies for limiting pesticide exposure to vegetable consumers.
