Due to the increasing food demand, the use of pesticides in agriculture is increasing. Particularly in low income
countries poor training among farmers, combined with the use of obsolete pesticides may result in a high risk
for the consumers. In this study six organochlorines and five organophosphates were analyzed in 54 samples
of tomatoes from small scale farmers in Bolivia. The analyses were done on unprocessed, stored, washed and
peeled tomatoes. The cumulated risk associated with consumption of the tomatoes after different storage
times and processing treatments was evaluated using the Hazard Index (HI) for acute risk assessment. All 11 pesticides
were detected in the analyses although several of them are obsolete and included in the Stockholm convention
ratified by Bolivia. The organochlorines were found in the μg pesticide/kg tomato range and below the HI,
while the organophosphates were present in the mg pesticide/kg tomato range and most often above the HI. The
loworganochlorine concentrationswere not significantly affected by time or treatment, but storage significantly
decreased the concentrations of organophosphates. Washing decreased the initial concentrations to between
53% (malathion) down to 2% (ethyl parathion), while peeling had a larger effect reducing the initial concentrations
to between 33% (malathion) and 0.7% (chlorpyriphos). Both the acute and chronic cumulative risk assessment
of organophosphates showed a dietary risk for unprocessed tomatoes three days after harvest. For children,
also the consumption of washed tomatoes constituted a dietary risk. To reduce the dietary risk of pesticide residues
in Bolivia, there is an urgent need of farmer education and introduction of less hazardous pesticides as
well as resources for surveillance and enforcement of legislation in order to ensure public health.