Pesticide and veterinary drug residues in honey - validation of methods and a survey of organic and conventional honeys from Slovenia.

Four analytical methods were developed and validated for the determination of veterinary drug residues and environmental pesticide residues in honey: (a) GC-MS method for the analysis of amitraz and all metabolites containing the 2,4-dimethylaniline moiety; (b) GC-MS method for the analysis of thymol, chlorfenvinphos and coumaphos; (c) GC-MS method for the analysis of 75 active substances; (d) LC-MS/MS method for the analysis of 60 active substances. Between the GC-MS (method c) and the LC-MS/MS method (method d) there was no overlap among active substances, meaning that using both methods 135 active substances originating from the environment in total were included and validated. The first method involved hydrolysis of amitraz and its metabolites containing the 2,4-dimethylaniline moiety to 2,4-dimethylaniline and extraction of 2,4-dimethylaniline to n-hexane. The other three methods had the same extraction procedure with a mixture of solvents: acetone, dichloromethane and petroleum ether. All 4 methods were tested in practice. Sixty samples of honey were analysed: 22 from organic and 38 from conventional production. Overall, residues were mainly higher than reported in literature but did not exceed MRLs. Risk assessment confirmed that the analysed samples are of no cause for concern for consumers.

Nitrate and nitrite contamination of vegetables in the Slovenian market.

Overview of the quality of domestic and imported vegetables in Slovene market was investigated in terms of nitrate and nitrite contamination. In total, 145 samples (rocket, lamb's lettuce, silverbeet, spinach, lettuce, cabbage, radicchio, string beans, carrots, cucumber, potato, cauliflower, pepper and tomato) were bought in supermarkets and market places in Ljubljana in 2017. Values over 1000 mg NO3- kg-1 were found in 30% of randomly selected samples. The highest nitrates (4000-7600 mg kg-1) were determined in rocket, lamb's lettuce, silverbeet, and spinach. They were bought in supermarkets declared as imported samples. Regarding EU regulatory limits, available for rocket, lettuce, and spinach, 17% of the samples exceeded the threshold values. Furthermore, some of them were designated as ecological product (ECO). There are no maximum limits for lamb's lettuce; however, all samples from supermarkets, declared as imported samples, contained very high values of nitrates (>3500 mg NO3- kg-1).

Exposure to pesticides at sublethal level and their distribution within a honey bee (Apis mellifera) colony.

Honey bee colonies were exposed to pesticides used in agriculture or within bee hives by beekeepers: coumaphos; diazinon; amitraz or fluvalinate. Samples of bee workers, larvae and royal jelly were analysed using Gas Chromatography-Electron Capture Detection (GC-ECD). Amitraz was quantified using High Performance Liquid Chromatography (HPLC), and Gas Chromatography-Tandem Mass Spectrometry (GC/MS/MS) was used for quantification of diazinon. Sixth day after treatment, coumaphos was found in the royal jelly (250 ng/g) secreted by nurse workers and fluvalinate was found in both bee heads (105 ng/g, 8 days after treatment) and in larvae (110 ng/g, 4 days after treatment). Amitraz residues in all sampled material were below the level of detection of 10 ng/g. Diazinon was not detected in any of the analysed samples. The large quantities of fluvalinate found in bee heads and larvae, the coumaphos residues in royal jelly, and additional potential sub-lethal effects on individual honey bees or brood are discussed.

A survey of nitrate and nitrite content of fruit and vegetables grown in Slovenia during 1996-2002.

Monitoring of nitrate (NO(3)(-)) and nitrite (NO(2)(-)) content in agricultural products in Slovenia has been carried out since 1996. The results of monitoring over the period 1996-2002 are presented. During this time 924 samples of 14 different agricultural products (potato, lettuce, apples, carrot, silage maize, cabbage, grapes, peaches, string beans, cereals, pears, cucumbers, strawberries and tomato) were analysed. The samples were taken at the time of maturity directly from growing sites and they were analysed using segmented flow analysis. The average nitrate contents were the highest in lettuce (1,074 mg kg(-1)), cabbage (881 mg kg(-1)), string beans (298 mg kg(-1)) and carrot (264 mg kg(-1)), and they were moderately high in potato (158 mg kg(-1)), silage maize (122 mg kg(-1)), strawberries (94 mg kg(-1)), cucumbers (93 mg kg(-1)) and cereals (49 mg kg(-1)). Low nitrate contents (below 6 mg kg(-1)) were found in fruit (grapes, peaches, apples and pears) and tomato. With the exception of cereals (8.9 mg kg(-1)), apples (1.5 mg kg(-1)), potato (1.2 mg kg(-1)) and pears (1.0 mg kg(-1)) the content of nitrites did not exceed 0.5 mg kg(-1). It may be concluded that the results of the monitoring were in most cases similar to the results of investigations obtained in other countries.