Uptake and toxicity of polycyclic aromatic hydrocarbons in terrestrial springtails—studying bioconcentration kinetics and linking toxicity to chemical activity

Abstract

Abstract-Passive dosing applies a polymer loaded with test compound(s) to establish and maintain constant exposure in laboratory experiments. Passive dosing with the silicone poly(dimethylsiloxane) was used to control exposure of the terrestrial springtail Folsomia candida to six polycyclic aromatic hydrocarbons (PAHs) in bioconcentration and toxicity experiments. Folsomia candida could move freely on the PAH-loaded silicone, resulting in exposure via air and direct contact. The bioconcentration kinetics indicated efficient uptake of naphthalene, anthracene, and pyrene through air and (near) equilibrium partitioning of these PAHs to lipids and possibly the waxy layer of the springtail cuticle. Toxicities of naphthalene, phenanthrene, and pyrene were related to chemical activity, which quantifies the energetic level and drives spontaneous processes including diffusive biouptake. Chemical activity-response relationships yielded effective lethal chemical activities (La50s) well within the expected range for baseline toxicity (0.01-0.1). Effective lethal body burdens for naphthalene and pyrene exceeded the expected range of 2 to 8 mmol kg À1 fresh weight, which again indicated the waxy layer to be a sorbing phase. Finally, chemical activities were converted into equilibrium partitioning concentrations in lipids yielding effective lethal concentrations for naphthalene and phenanthrene in good correspondence with the lethal membrane burden for baseline toxicity (40-160 mmol kg À1 lipid). Passive dosing was a practical approach for tightly controlling PAH exposure, which in turn provided new experimental possibilities and findings. Environ. Toxicol. Chem. 2013;32:361-369. # 2012 SETAC

Linking algal growth inhibition to chemical activity: Excess toxicity below 0.1% of saturation

“…This range is fairly independent of the type of HOC and the target organism. The explanations for these observations are: (1) chemical activity controls equilibrium partitioning (from high to low chemical activity) and thereby the diffusive uptake and internal distribution of HOCs in organisms (Di Toro et al, 1991;Reichenberg and Mayer, 2006;Schmidt et al, 2013)…”

Simultaneous Control of Phenanthrene and Drought by Dual Exposure System: The Degree of Synergistic Interactions in Springtails was Exposure Dependent

“…30 This difference is most likely owing to the longer period for the springtails to recover from sublethal stress in the current study (overnight) compared to the much shorter recovery period of 2 h in the previous study. 30 With decreasing water activity (i.e., with increasing drought stress) the La PHE 50 -value decreased for the organisms surviving the given drought stress level, and the model thereby expressed the synergy in the data set ( Figure 5A). However, the degree of synergy was clearly exposure dependent with only minor synergy under sublethal drought stress conditions (down to about a water = 0.990), 8,13,15,31,42 where La PHE 50 dropped a maximum of just 14% relative to control conditions at a water = 0.998 ( Figure 5A).…”

Headspace passive dosing of volatile hydrophobic chemicals – Aquatic toxicity testing exactly at the saturation level

“…The preparative work for the partitioning donor was also vastly reduced compared to other passive dosing approaches. For instance, in the passive dosing approaches using silicone polymer there are several steps for preparing the donor, which involve: (1) the selection and dimensioning of the donor material to ensure negligible depletion, (2) the careful cleaning of the donor material prior to loading, and (3) the loading of test substances into the donor material (Butler et al, 2013;Engraff et al, 2011;Schmidt et al, 2013;Seiler et al, 2014;Smith et al, 2013). Hence, the simple preparation of the donor also made the HS-PD approach more versatile by allowing testing both at, and just below, the saturation level.…”