Transfer of xenobiotics from contaminated beeswax into different bee matrices under field conditions and the related exposure probability

Beeswax is known to have a high capacity to accumulate different contaminants due to its fat-soluble properties. Many surveys in Europe and the USA have shown high levels of contamination in beeswax especially with acaricides used for varroa treatment. In this study, we investigated the transfer pathways of various active substances from beeswax into different matrices under field conditions. Honey, bee bread, larvae, and pupae samples were collected 6-8 weeks after building the experimental colonies on different charges of wax foundations. Identification and quantification of the target substances were performed with an established and validated multi-residue method using LC-MS/MS and GC-MS systems. Nine out of 19 active substances in wax could be detected in the analyzed matrices. Our results confirm the migration of different contaminants from wax into different bee matrices including honey, bee bread, and bee brood. The concentration of detected residues in the different matrices was significantly increased by increasing residue concentration in wax. Therefore, the maximum detected residues in the matrices were almost in wax containing high residual concentrations. Bee bread can be considered as the most important matrix due to relatively high detected concentrations and transfer ratios of the most contaminants. A significant effect of the lipophilicity of active substances on the transfer ratio into bee bread was found, which means that increasing the Log P values has positive effects on the transfer ratio. In conclusion, our results provide the first detailed information regarding the migration of active substances from wax into various matrices under realistic field conditions and are fundamentally important for assessing potential exposure and risks for honey bees.