Evaluation of the Effect of Wastewater Irrigation on the Microbiological Quality of Vegetables in Northeast Ethiopia: Implication for Food-Borne Infection and Intoxications

BACKGROUND: Cultivation of vegetables using untreated wastewater is a common phenomenon in many drought-prone areas of the world. Consumption of such microbiologically unsafe vegetable increase the risk of food-borne diseases. As a result, evaluating the effect of wastewater irrigation on the microbiological quality of vegetables would be beneficial to consumers’ health. METHOD: A total of 192 vegetable samples (lettuce, cabbage, carrot, and tomato) and 64 irrigation water samples were collected and analyzed for total bacteria and coliform count using a standardized protocol over a 4 month period. One-way analysis of variance and Pearson correlation coefficient was used to analyze the data. Statistical significance was defined at a P-value of less than 0.05. RESULT: Carrots were the least polluted vegetable, according to the study, while cabbage had the highest contamination levels. The mean bacterial count among the vegetables differs significantly (P < 0.05). The fecal coliform counts of the irrigation wastewater exceed the international wastewater irrigation standards. The mean microbial count between vegetables and water samples showed a significant positive relationship (P < 0.05). All of the analyzed vegetable samples were of borderline microbial quality for fecal coliform bacteria. CONCLUSION: Irrigation wastewater has a low microbiological quality, which significantly contributes to the contamination of vegetables grown on it. RECOMMENDATION: Measures should be taken to improve the microbial quality of wastewater as well as the quality of vegetables grown in order to protect consumers’ health from food-borne diseases.