Experimental study: uptake of coccidiostats in vegetables

This project aimed at obtaining experimental data related to the uptake of coccidiostats authorised in the European Union particularly in vegetables grown on poultry manure-amended soils. An animal trial (poultry) and a plant trial (carrot, lettuce, potato, tomato and courgette) were performed while LC-MS/MS methods for feed, manure, litter and vegetables were developed. Ratios between the residue concentration in the poultry manure and the concentration in the feed varied from 5 to 38%. The effects of storing manure (4-83% decrease) and composting litter (79-98% decrease) on coccidiostat concentrations were investigated.

Results for the raw vegetables indicate that coccidiostats can be incorporated into vegetables from the soil. However, detected concentrations are relatively low (<LOQ – 47.5 µg/kg) and mostly originated from vegetables grown on soil spiked with premixes (= worst-case scenario, not representative for commercial application, consequently it is unlikely to obtain these levels outside of this experimental study). Within the manure-amended soils, there was uptake of nicarbazin in carrots (1.21 ± 0.11 µg/kg) and monensin in lettuce (0.93 ± 0.72 µg/kg). These low concentrations of nicarbazin and monensin in carrots and in lettuce indicate that the exposure to them from vegetables will most likely not contribute significantly to the overall human exposure to coccidiostats.

The influence of food processing on the concentration of coccidiostats was investigated, as well as a distribution study in potatoes (peel versus flesh). These results revealed that boiling as well as baking efficiently decreased the contamination levels in the samples. Peeling the potato samples also showed to be effective at reducing the levels.