Toxicity and bioaccumulation of biosolids‐borne triclosan in food crops

Abstract

Triclosan (TCS) is an antimicrobial compound commonly found in biosolids. Thus, plants grown in biosolids-amended soil may be exposed to TCS. We evaluated the plant toxicity and accumulation potential of biosolids-borne TCS in two vegetables (lettuce and radish) and a pasture grass (bahia grass). Vegetables were grown in growth chambers and grass in a greenhouse. Biosolids-amended soil had TCS concentrations of 0.99, 5.9, and 11 mg/kg amended soil. These TCS concentrations represent typical biosolids containing concentrations of 16 mg TCS/kg applied at agronomic rates for 6 to 70 consecutive years, assuming no TCS loss. Plant yields (dry wt) were not reduced at any TCS concentration and the no observed effect concentration was 11 mg TCS/kg soil for all plants. Significantly greater TCS accumulated in the below-ground biomass than in the above-ground biomass. The average bioaccumulation factors (BAFs) were 0.43 ± 0.38 in radish root, 0.04 ± 0.04 in lettuce leaves, 0.004 ± 0.002 in radish leaves, and <0.001 in bahia grass. Soybean (grain) and corn (leaves) grown in our previous field study where soil TCS concentrations were lower (0.04-0.1 mg/kg) had BAF values of 0.06 to 0.16. Based on the data, we suggest a conservative first approximate BAF value of 0.4 for risk assessment in plants.

Plant uptake of pharmaceutical and personal care products from recycled water and biosolids: a review

“…Methanol and acetonitrile are usually used as the organic mobile phase, where 0.001-0.1% formic acid or acetic acid is often added to improve LC performance and MS detection sensitivity. Gas chromatography (GC)-MS has also been used by several researchers for analyzing acidic PPCPs (e.g., triclosan, ibuprofen, diclofenac, clofibric acid), but derivatization using derivatization agents such as trimethylsulfonium hydroxide (TMSH), bis(trimethylsilyl)trifluoroacetamide (BSTFA), and trimethylchlorosilane (TMCS) is needed before the analysis (Calderón-Preciado et al, 2009;Pannu et al, 2012). The MS system is usually equipped with electrospray ionization (ESI) ( Table 1), as it provides better sensitivity than atmospheric pressure chemical ionization (APCI) for pharmaceuticals such as cytotoxic drugs cyclophosphamide and ifosfamide (Llewellyn et al, 2011).…”

Comments on “Human health risk assessment of pharmaceuticals and personal care products in plant tissue due to biosolids and manure amendments, and wastewater irrigation”

“…Such cases are not only unrealistic in terms of commercial agronomic practices but they may also foster unrealistic scenarios in terms of the biological, physical and chemical processes that PPCPs may undergo in the soil that in turn will affect their bioavailability and uptake. Furthermore, several of the reviewed studies failed to report proper methodology (Pannu et al, 2012), detection limits (Gottschall et al, 2012) or presented results where the control was either equal to or even higher in PPCP concentration than the treated plants (Sabourin et al, 2012). Critical review of the cited articles is missing.…”

Risk assessment of persistent pharmaceuticals in biosolids: Dealing with uncertainty

“…Although PPCPs levels in biosolids or reclaimed water are not restricted to date, accumulation in soil [24] and transfer to water [25], soil-earthworms [24], crops and grass [26,28] was demonstrated, although in some cases, levels of no concern were reported [29]. While plant accumulation but not toxicity was reported [30], phytotoxicity was observed in plants exposed to a mixture of these compounds [31]. Hence, ecological risks derived from the accumulation of these compounds in the long-term should also be analysed.…”

“…Once applied in soil, carbamazepine is distributed between soil parti- cles and soil solution, and can translocate through plant shoot until reaching leaves [26,28,76]. The much higher lipophilic triclosan, barely present in soil solution, is preferentially found in the roots, due to the contact by soil particles [28,30,31,76]. Its high concentration in soil also results in a higher bioaccumulation in cattle meat and milk.…”