Bioavailability of phthalate congeners to earthworms (Eisenia fetida) in artificially contaminated soils

Abstract

Bioavailability of phthalate congeners, dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate (DBP), di-(2-ethylhexyl) phthalate (DEHP), and dioctyl phthalate, to earthworms (Eisenia fetida) were studied when earthworms were exposed to two artificially contaminated agricultural and forest soils. Only DBP and DEHP were detected in earthworms. The uptake kinetics of DBP and DEHP in earthworms was fast within the initial 10 days followed by a nearly steady state for the subsequent 20 days. An equilibrium partitioning model could be used to describe the uptake kinetics of DBP and DEHP by earthworm in two types of soils (r ¼ 0:70920:864). The average biota-to-soil accumulation factors (BSAFs) of DBP and DEHP at 5 mg kg À1 in soil were 0.2770.07 and 0.1770.03, respectively, in agricultural soil, while the BSAFs were 0.2170.06 and 0.0770.02, respectively, in forest soil. The concentrations of phthalates in earthworms increased with increasing concentrations of phthalates in soil. There was a significant correlation between log C soil and log C worm , with r ¼ 0:99920:993, demonstrating a single linear partitioning of phthalates between soil and earthworms. The bioavailability of DBP and DEHP was assessed by Soxhlet, methanol, and methanol-water (1:1) extraction methods. Our results indicated that the extractable amounts of freshly added DBP and DEHP in soils by these extraction methods were significantly correlated with those in earthworms. It was observed that the extractable DBP and DEHP by the methanol and methanol-water (1:1) extraction methods decreased with their increasing residence time in soil. In contrast, the amount extracted by the Soxhlet extraction method did not show a similar decline. Therefore, Soxhlet extraction was a poor indicator of the bioavailability of DBP and DEHP to earthworms in soil, which could lead to overestimation of the risk of soilassociated DBP and DEHP. The extractable DBP and DEHP by methanol and methanol-water (1:1) significantly decreased over 440 days. Compared with the methanol-water (1:1) extraction method, the methanol extraction method was preferred for its ability to predict the bioavailability of DBP and DEHP in aged soils. r

Organic contaminants in sewage sludge (biosolids) and their significance for agricultural recycling

“…Accumulation of DBP and DEHP has been reported in some mesofauna, suggesting a potential risk to these organisms (e.g. Hu et al 2005) and the bioaccumulation through natural food chains, although the compounds were artificially introduced into soil by direct spiking without sludge, which may exaggerate their apparent bioavailability. However, no significant adverse effects of DEHP or DBP were observed by Jensen et al (2001b) on soil collembolans.…”

Separation and determination of phthalates by micellar electrokinetic chromatography

“…The gas chromatography with electron capture detector (GC-ECD) was the most common method for the determination of phthalates in the environment [7,8]. The GC with flame ionization detector (GC-FID) was also used when phthalates were in polar solvents [9].…”

Dibutylphthalate and Tween 80 alter ultrastructure inCandida albicans: implications for peroxisome proliferation

“…Inconsistencies in sample testing were attributed to the presence of contaminants or to differences in metabolic activation (Zacharewski 1997). Irregularities in the case of phthalates might also be associated with differences in chemical bioavailability, particularly when solubility is a consideration (Hu et al 2005). The surfactant Tween 80 has been incorporated in a number of experimental procedures, primarily to promote chemical solubility.…”