Pesticides in the urban environment: Targeted and non-targeted screening of pesticide profiles in urban honey from Montreal by LC-QTOF-MS.

The safety of urban honey is a growing concern due to pesticide contamination, necessitating effective monitoring methods. Small-scale urban beekeeping has emerged as a promising solution to counter the honeybee population decline and high honey demand. However, urban pesticides pose risks as bees unintentionally collect them while foraging, leading to pesticide residue accumulation in honey. This issue has been substantiated by various reports confirming the occurrence of pesticides in urban settings and their detection in honey, underscoring the importance of addressing this concern for both honey producers and consumers. Recognized as a promising approach for pesticide residue monitoring in food samples, non-targeted analysis (NTA) has gained significant attention. While non-targeted studies have increased, honey-focused research is limited, and as far as we know, no studies have been conducted on urban honey to better understand human exposure to pollutants in such honey. To address these concerns, in Chapter 3, a direct injection technique coupled with high-performance liquid chromatography and quadrupole time-of-flight mass spectrometry was employed as an NTA to detect pesticides in urban honey. The technique was validated according to the SANCO guideline recommendations for 21 key pesticides and was assessed to be robust and sensitive for this application. It was able to detect pesticide residues 2 to 1000 times below Canada's 0.1 ppm limit and yielded comparable results to methods involving prior sample preparation. The instrument linearity, repeatability, and recoveries met satisfactory criteria, ensuring the method's reliability. Subsequently, the method was applied for targeted (79 pesticides) and non-targeted screenings of 118 urban honey samples collected from Montreal, Canada in 2021. None of the 79 pesticide residues were present at levels above the Limit of Detection (LOD) suggesting that targeted pesticides are of no concern. However, employing an NTA revealed the presence of 111 compounds tentatively identified with scores above 80%, highlighting the need for additional study. The physicochemical parameters of urban honey and rural Quebec honey were assessed and showed to be similar, except for urban honey's slightly higher electrical conductivity. This shows that physicochemical features alone cannot distinguish urban from rural honey. The developed method effectively detected pesticides in urban honey, while the NTA identified unknown compounds warranting further investigation. Additionally, the comprehensive analysis of urban honey samples, including moisture content, pH, and electrical conductivity, provided valuable insights into the quality of honey collected from Montreal in 2021. In Chapter 4, the investigation aimed to evaluate the potential of pesticide measurements in urban honey and air as mutually beneficial and supplementary approaches by comparing the results with those obtained from an artificial XAD-resin-based passive air sampler (PAS). 118 urban honey samples were collected from Montreal, while 40 sites across Montreal were selected for the deployment of the XAD-PAS over three months during the summer of 2021. The screening technique combining an NTA and HPLC-QTOF-MS was used to identify pesticides in both matrices obtained from urban areas. The method was effective in identifying targeted compounds of interest. The insect-repellent DEET was found in 28 of the 40 passive air samplers analyzed. While DEET, a known environmental contaminant, was found in PASs, its presence could not be unequivocally identified in the urban honey samples. None of other target pesticides were detectable in the PAS. The findings from this study offer proof that measuring pesticides in both urban honey and air can effectively function as complementary and advantageous methods. In summary, this study showcased the effectiveness of NTA in enhancing our understanding of the presence of contaminants in urban honey

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