Journal Article

Co-exposure risks of pesticides residues and bacterial contamination in fresh fruits and vegetables under smallholder horticultural production systems in Tanzania

Sadik, Omowunmi, Ndakidemi, Patrick A., Kapeleka, Jones A., Sauli, Elingarami

2020

Overview

This study was carried out to investigate the risks of simultaneous exposure to pesticide residues and bacteria contaminants in locally produced fresh vegetables and vegetables in Tanzania. A total of 613 samples were analyzed for pesticide residues, out of which 250 were also analyzed for bacterial contamination. Overall, 47.5% had pesticide residues, 74.2% exceeded Maximum Residue Levels (MRLs). Organophosphorus (95.2%), organochlorines (24.0%), pyrethroids (17.3%), and carbamates (9.2%) residues dominated. MRL values were mostly exceeded in tomatoes, onions, watermelons, cucumbers, Chinese cabbage, and sweet paper. Tetramethrin (0.0329-1.3733 mg/kg), pirimiphos-methyl (0.0003-1.4093 mg/kg), permethrin (0.0009-2.4537 mg/kg), endosulfan (beta) (0.0008-2.3416 mg/kg), carbaryl (0.0215-1.5068 mg/kg), profenofos (0.0176-2.1377 mg/kg), chlorpyrifos (0.0004-1.2549 mg/kg) and dieldrin (0.0011-0.5271 mg/kg) exceeded MRLs. The prevalence of bacteria contamination was high (63.2%). Enterobacter (55.6%) Pseudomonas aeruginosa (32.4%), E. coli (28.2%), Citrobacter (26.8%), Klebsiella oxytoca (14.8%), and Salmonella (7.7%) were isolated. Furthermore, 46.4% tested positive for both pesticide residues and bacterial contaminants. Vegetables from farms (60.7%) contained more dual contaminants than market-based vegetables (41.8%). This may have resulted from excessive pesticide use and unhygienic handling of fresh fruits and vegetables at production level. Binary logistic regression showed that fresh fruits and vegetables with pesticide residues were 2.231 times more likely to have bacteria contaminants (OR: 2.231; 95% CI: 0.501, 8.802). The contamination levels of pesticide residues and bacterial contaminants could be perceived as a serious problem as most fresh fruits and vegetables recorded values of pesticide residues far above the MRLs with pathogenic bacteria isolated in higher proportions. MRLs was higher in most vegetables consumed raw or semi-cooked such as watermelons, carrots, cucumber, tomatoes, onion and sweet paper. There is an urgent need to develop pesticide monitoring and surveillance systems at farmer level, educating farmers and promoting the use of greener pesticides to mitigate the health effects of pesticides and bacterial contaminants.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Agricultural pollution / Agricultural production / Bacteria / Bacterial infections / Biology and Life Sciences / Carbamate pesticides / Carbamates (tradename) / Carbaryl / Carrots / Causes of / Chinese cabbage / Chlorpyrifos / Chromatography / Citrobacter / Citrobacter - isolation & purification / Citrobacter - pathogenicity / Contaminants / Contamination / Crop diseases / Crops / Cucumbers / Dieldrin / Distribution / E coli / Endosulfan / Enterobacter - isolation & purification / Enterobacter - pathogenicity / Environmental science / Exposure / Farmers / Farms / Food contamination / Food contamination & poisoning / Food Contamination - analysis / Food safety / Foodborne diseases / Fruit - adverse effects / Fruit - chemistry / Fruit - microbiology / Fruits / Fruits (Food) / Health aspects / Horticulture / Humans / Hydrocarbons, Chlorinated - adverse effects / Hydrocarbons, Chlorinated - chemistry / Insecticides / Klebsiella / Klebsiella oxytoca - isolation & purification / Klebsiella oxytoca - pathogenicity / Laboratories / Levels / Mandela, Nelson / Medicine and Health Sciences / Onions / Organochlorine compounds / Permethrin / Pesticide pollution / Pesticide residues / Pesticide Residues - adverse effects / Pesticide Residues - chemistry / Pesticides / Pesticides - adverse effects / Pesticides - chemistry / Physical Sciences / Phytopathogenic bacteria / Pirimiphos-methyl / Pollution monitoring / Pseudomonas aeruginosa / Pseudomonas aeruginosa - isolation & purification / Pseudomonas aeruginosa - pathogenicity / Public health / Pyrethrins - adverse effects / Pyrethrins - chemistry / Pyrethroids / Regression analysis / Residues / Risk factors / Salmonella / Salmonella - isolation & purification / Salmonella - pathogenicity / Surveillance systems / Tetramethrin / Tomatoes / Vegetables / Vegetables - adverse effects / Vegetables - chemistry / Vegetables - microbiology / Water melons