Analysis of imidacloprid in different food commodities
A total of 250 samples were analyzed. Samples of fruits, fruit juices, and baby foods (50 samples each), vegetables (70 samples), and cereals (30 samples) were analyzed for the presence of imidacloprid residues. Imidacloprid was not detected in samples of fruit juices and baby foods. Similarly, apple and peach juice of Turkey and sugarcane juice of Brazil have shown no pesticide residues 18, 19. However, some studies have reported traces of pesticides in fruit-based soft drinks of Spain 20. Thus, these two food commodities may be free from imidacloprid due to their processing. However, imidacloprid was detected in 38 samples of fruits, vegetables, and cereals, which represents around 15.20% of the total samples. Imidacloprid was observed in 22% of fruit samples, and 2% of samples were above the MRL.
The level of imidacloprid ranged from 0.02 to 0.26 mg/kg in apples, from levels not detectable to 0.04 mg/kg in bananas, from 0.019 to 0.13 mg/kg in oranges, and from 0.04 to 0.78 mg/kg in grapes (Table 1). Imidacloprid was not detected in any of the samples of pomegranates. However, one sample of grapes showed imidacloprid residue above the MRL (0.50 mg/kg).
Although imidacloprid was detected in 24% of vegetable samples, only 5.71% showed imidacloprid above the MRL (http://www.codexalimentarius.net/pestres/data/pesticides/details.html?id=206). The presence of imidacloprid residues was in the following order: potato > cauliflower > cabbage > tomato > eggplant > bell pepper > okra. Of cereals, 33% of samples showed imidacloprid, but only 3% of samples were above the MRL (0.05 mg/kg).
Imidacloprid residues were also reported in vegetables and fruits of Palestine. The imidacloprid concentration in several crops of Palestine was found to exceed the MRL 21. Fernandez-Alba et al. 22 found imidacloprid residues in 25 to 53% (average 21%) of 200 samples of fruits and vegetables analyzed from Almeria, Spain.
Many countries have legal directives to control levels of pesticides in food through the MRL, to protect consumers' health (http://www.who.int/foodsafety/publications/chem/regional_diets) 23, 24. The level of pesticide residues in food commodities are legislated to minimize exposure of consumers to unnecessary intake of pesticides and to ensure their judicious use. From a potential health perspective, it is necessary to compare exposure estimates to find out toxicological criteria such as EDI.
The results of the present study have been used to calculate the EDI, expressed as microgram pesticides per kilogram body weight. The EDI is a real estimate of pesticide exposure that was calculated as per the international guidelines 25, 26 using the following equation: EDI = ∑C × F/D × W, where C is the average imidacloprid concentration in each commodity (micrograms per kilogram), F is the mean annual intake of food per person (kilograms), D is the number of days in a year (365), and W is the mean body weight (60 kg).
The annual intake per person of fruits, vegetables, wheat, rice, and pulses were 9.5, 23, 52.8, 66, and 12 kg, respectively, according to an Indian survey performed in the years 1975 to 2000 and 2005 to 2006 (http://mospi.nic.in/mospi_nsso_rept_pubn.htm) 27, 28. The average level of imidacloprid in each food commodity, the annual consumption of individual commodities per person, the EDI, and acceptable daily intakes (micrograms per kilogram body weight) established by the Food and Agriculture Organization and the World Health Organization 29, 30 are compared in Table 2. The EDIs have been calculated between 0.004 and 0.131 µg/kg body weight, while the hazard indices (EDI/acceptable daily intake) ranged from 0.007 to 0.218 for the tested commodities.
Table 2. Calculation of estimated daily intake and hazard index of imidacloprid in different food commodities
|Commodity||Average imidacloprid concentration in commodity (∑C) (µg/kg)||Mean annual intake of commodity per person (kg) (F)||No. days in year (D)||Average weight of person (W)||ADI (µg/kg bw daily)||EDI (µg/kg bw daily)||Hazard index|
It is therefore indicated that lifetime consumption of vegetables, fruits, fruit juices, baby foods, wheat, rice, and pulses may not pose health hazards for the population of Lucknow because the hazard indices for imidacloprid residues were below 1 31. It is reported that common home processing removes significant amounts of pesticides from vegetables 32. Therefore, the health hazard due to imidacloprid residue in vegetables, fruits, fruit juices, baby foods, wheat, rice and pulses may not be of great concern. Monitoring of pesticide residues in food is a priority objective for ensuring compliance with good agriculture practices and their judicial use and to avoid possible risk to human health.