Mumbai watermelon deaths: Food scientist explains how pesticide residues in fruit impact your health

What are pesticide residues?

Pesticide residues refer to the trace amounts of chemical compounds that remain on fruits and vegetables after pesticides are sprayed during cultivation. These residues may persist when farmers apply pesticides in quantities higher than recommended, spray crops too close to harvest, or fail to observe mandatory waiting periods between application and sale.

To regulate exposure, the Food Safety and Standards Authority of India (FSSAI) prescribes Maximum Residue Limits, or MRLs, which define the highest legally permissible concentration of pesticide residue in food, expressed in milligrams per kilogram (mg/kg). Any produce exceeding this threshold is considered non-compliant with food safety standards.

Have pesticide residues crossed limits on fruits?

Recent surveillance by FSSAI (Food Safety and Standards Authority of India) has shown residue violations in commonly consumed fruits. “In some samples, pomegranate was found with difenoconazole levels of 0.03 mg/kg against the FSSAI limit of 0.01 mg/kg, while oranges showed quinalphos at 0.10 mg/kg against the permissible 0.05 mg/kg. Grapes have also recorded fipronil and carbendazim concentrations far above accepted limits, while traces of chlorpyrifos and lambda-cyhalothrin have been detected beyond prescribed thresholds in certain fruit categories,” says Dr Kamble. Maharashtra, Uttar Pradesh, Punjab and Haryana remain among the states with the highest pesticide consumption in agriculture.

Can pesticide poisoning be fatal?

While acute poisoning from routine fruit consumption is considered highly unlikely, chronic exposure to elevated pesticide residues is a legitimate public health concern. Over time, repeated ingestion of chemical residues above safe limits may contribute to cumulative toxicity. Studies have linked long-term exposure to certain pesticides with kidney dysfunction, endocrine disruption, neurological disorders, developmental complications in children and an increased risk of some cancers. Organophosphates and carbamate-based pesticides are of particular concern because of their potential to affect the nervous system over prolonged exposure.

Watermelon, now under scrutiny because of the Mumbai case, can sometimes contain residues of compounds such as forchlorfenuron, a growth-enhancing chemical used to increase fruit size, as well as oxamyl and other organophosphate insecticides if used improperly. These chemicals, when present in excessive quantities, may trigger symptoms including nausea, vomiting, diarrhoea, dizziness and neurological distress. Artificial ripening agents such as calcium carbide and ethephon, though not pesticides in the strictest sense, are also frequently misused in fruit markets and may introduce toxic impurities including arsenic and phosphorus compounds.

How to prevent pesticide contamination

Dr Kamble stresses that prevention begins at the agricultural stage itself. “The simplest way to avoid pesticide residue concerns begins in agriculture through Good Agricultural Practices. The norms for pesticide use already exist. As consumers, fruits should be washed properly two to three times under tap water before consumption,” he says.

In the case of watermelon, cleaning becomes especially important because contamination on the rind can transfer to the edible flesh during cutting. Even though the fruit’s thick outer layer offers some protection, an unwashed rind can allow residues to move inside through knife contact.

Some food safety specialists also recommend soaking fruits in water with baking soda, salt or vinegar to further reduce surface contamination.

The Mumbai incident, though still under investigation, has renewed attention on a larger systemic issue: ensuring strict adherence to pesticide regulations from farm to market. As Dr Kamble notes, “Prevention starts in agriculture itself. Good Agricultural Practices remain the first line of defence.”