Accumulation of contaminants of emerging concern in food crops—part 2: Plant distribution

Abstract

Arid agricultural regions often turn to using treated wastewater (reclaimed water) to irrigate food crops. Concerns arise, however, when considering the potential for persistent contaminants of emerging concern to accumulate into plants intended for human consumption. The present study examined the accumulation of a suite of 9 contaminants of emerging concern into 2 representative food crops, lettuce and strawberry, following uptake via the roots and subsequent distribution to other plant tissues. Calculating accumulation metrics (concentration factors) allowed for comparison of the compartmental affinity of each chemical for each plant tissue compartment. The root concentration factor was found to exhibit a positive linear correlation with the pH-adjusted octanol-water partition coefficient (DOW ) for the target contaminants of emerging concern. Coupled with the concentration-dependent accumulation observed in the roots, this result implies that accumulation of these contaminants of emerging concern into plant roots is driven by passive partitioning. Of the contaminants of emerging concern examined, nonionizable contaminants, such as triclocarban, carbamazepine, and organophosphate flame retardants displayed the greatest potential for translocation from the roots to above-ground plant compartments. In particular, the organophosphate flame retardants displayed increasing affinity for shoots and fruits with decreasing size/octanol-water partition coefficient (KOW ). Cationic diphenhydramine and anionic sulfamethoxazole, once transported to the shoots of the strawberry plant, demonstrated the greatest potential of the contaminants examined to be then carried to the edible fruit portion.

Potential emerging chemical risks in the food chain associated with substances registered under REACH

“…39 Finally, the uptake of TDCIPP in plants (strawberry, lettuce) was shown experimentally. 40,41 Overall, these data generally support the assessment of block C in this study. The fact that TDCIPP concentrations were below the limit of detection in all samples of the Norwegian study is somewhat surprising, but may be related to the methodology.…”

Nitenpyram degradation in finished drinking water

“…While the majority of this data came from the study of imidacloprid metabolites in bees, prudence suggests that an understanding of potential environmental breakdown products of other NNIs is required to ensure continued pollinator health . Indeed, such metabolite characterizations are becoming more important given the increasing use of reclaimed water and biosolids on food crops, which may result in the uptake of agrochemicals and their metabolites into plants …”

“…[2,8,9] Indeed, such metabolite characterizations are becoming more important given the increasing use of reclaimed water and biosolids on food crops, which may result in the uptake of agrochemicals and their metabolites into plants. [10,11] To understand the rapid loss of nitenpyram in unpreserved finished drinking water an investigation was carried out to identify nitenpyram degradation products using detailed fragmentation analysis. To conduct this investigation a liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOFMS) method was used to acquire high-resolution, accurate mass precursor and product ion data.…”

The potential implications of reclaimed wastewater reuse for irrigation on the agricultural environment: The knowns and unknowns of the fate of antibiotics and antibiotic resistant bacteria and resistance genes – A review

“…However, the movement of polar and ionizable antibiotics (the majority of antibiotics fall into this category) through plant cell membranes may be impeded by interactions with the negative surface potential of the cytoplasmic membrane (Trapp, 2004), by ion trapping, which is common for sulfonamides (Goldstein et al, 2014;Christou et al, 2016) and by sorption to plant cell walls (Trapp, 2004), making K ow an inappropriate indicator for the estimation of ionizable antibiotics movement within and through plant cells. The pH-dependent speciation of ionic compounds (D ow ) is considered to be a more appropriate descriptor for the ability of ionizable antibiotics to cross cell membranes and translocated within the plant than K ow (Wu et al, 2013b;Hyland et al, 2015).…”