Controlling and maintaining exposure of hydrophobic organic compounds in aquatic toxicity tests by passive dosing

Smith, Kilian E. C.; Dom, Nathalie; Blust, Ronny; Mayer, Philipp

doi:10.1016/j.aquatox.2010.01.007

Cited by 147 publications

(197 citation statements)

References 32 publications

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“…S. paucimobilis EPA505 was chosen since it degrades both phenanthrene and fluoranthene. 18 For culturing purposes, polydimethylsiloxane (PDMS) silicone (5 g) was cast into the base of 60 mL brown glass jars and loaded to saturation with fluoranthene by partitioning from a methanol suspension for 48 h. 14 The loading solution was decanted, surfaces were wiped using lint-free tissue, and residual methanol was washed away by three sequential washes with 20 mL of Milli-Q water.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…The HOC mass required for loading the silicone and the speed of depletion both depend on the size of the silicone reservoir. To economize on the use of 14 C substrate, a silicone O-ring format was selected to optimize this balance. These are also practical to handle and have a good passive dosing performance, 15 but of course, the format can be tailored according to the specific study requirements.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…After the final KOH sampling, 14 C activity in the bacterial suspension and O-rings were measured as above.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

“…After vigorous shaking and storing overnight in the dark, samples were counted with a program for 14 C measurements using a LS 1801 scintillation counter (Beckman).…”

Section: Environmental Science and Technologymentioning

confidence: 99%

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Dynamic Passive Dosing for Studying the Biotransformation of Hydrophobic Organic Chemicals: Microbial Degradation as an Example

Smith

Rein

Trapp

et al. 2012

Environ. Sci. Technol.

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Biotransformation plays a key role in hydrophobic organic compound (HOC) fate, and understanding kinetics as a function of (bio)availability is critical for elucidating persistence, accumulation, and toxicity. Biotransformation mainly occurs in an aqueous environment, posing technical challenges for producing kinetic data because of low HOC solubilities and sorptive losses. To overcome these, a new experimental approach based on passive dosing is presented. This avoids using cosolvent for introducing the HOC substrate, buffers substrate depletion so biotransformation is measured within a narrow and defined dissolved concentration range, and enables high compound turnover even at low concentrations to simplify end point measurement. As a case study, the biodegradation kinetics of two model HOCs by the bacterium Sphingomonas paucimobilis EPA505 were measured at defined dissolved concentrations ranging over 4 orders of magnitude, from 0.017 to 658 μg L −1 for phenanthrene and from 0.006 to 90.0 μg L −1 for fluoranthene. Both compounds had similar mineralization fluxes, and these increased by 2 orders of magnitude with increasing dissolved concentrations. First-order mineralization rate constants were also similar for both PAHs, but decreased by around 2 orders of magnitude with increasing dissolved concentrations. Dynamic passive dosing is a useful tool for measuring biotransformation kinetics at realistically low and defined dissolved HOC concentrations.

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Section: ■ Materials and Methodsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…After the final KOH sampling, 14 C activity in the bacterial suspension and O-rings were measured as above.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

“…After vigorous shaking and storing overnight in the dark, samples were counted with a program for 14 C measurements using a LS 1801 scintillation counter (Beckman).…”

Section: Environmental Science and Technologymentioning

confidence: 99%

See 2 more Smart Citations

Dynamic Passive Dosing for Studying the Biotransformation of Hydrophobic Organic Chemicals: Microbial Degradation as an Example

Smith

Rein

Trapp

et al. 2012

Environ. Sci. Technol.

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“…Chemical activity (a HOC , dimensionless) can be related to the concentration (C HOC , mol L À1 ) via a compound-and medium-specific activity coefficient (g HOC , L mol À1 ) [7] a HOC ¼ C HOC Â g HOC (2) Chemical activity is an established concept in physical chemistry and the basis for the equilibrium partitioning theory that is often used to link total soil and sediment concentrations to actual concentrations in organisms [8]. More recently, various passive sampling techniques have been developed to measure chemical activity [2,9,10], and passive dosing techniques have been developed to control chemical activity in laboratory tests [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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

Schmidt

Smith

Holmstrup

et al. 2012

Enviro Toxic and Chemistry

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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

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Aquatic toxicity tests with substances that are poorly soluble in water and consequences for environmental risk assessment

Weyman¹,

Rufli

Weltje³

et al. 2012

Enviro Toxic and Chemistry

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Aquatic toxicity tests with substances that are poorly soluble in water have been conducted using different methods, and estimates of toxicity have varied accordingly. The present study illustrates differences in toxicity values resulting from variation in test designs and solution preparation methods, and offers guidance on the best way to conduct these tests. Consequences for environmental risk assessment and classification are also discussed. The present study mainly considers active ingredients of plant protection products, but is also considered relevant to other chemicals. It is recommended that toxicity tests be conducted only up to the saturation limit, dispersants avoided, and solvents used only if necessary to support handling and speed of dissolution. Analytical measurements of exposure concentrations should reflect what organisms are exposed to. If acute toxicity testing at the saturation limit yields no adverse effects, further testing should not normally be required; the toxicity value of the endpoints should be considered as the saturation limit and adverse classification should not be required. Chronic testing, if required, should then be conducted at the practical saturation limit as this is the most realistic worst-case exposure scenario. If no adverse effects occur, the risk should be acceptable because higher aqueous exposure cannot occur. This could be substantiated by testing additional species. Assessment factors on no observed effect concentration (NOEC) values at the saturation limit require careful consideration in the risk assessment to avoid unnecessarily low regulatory acceptable concentrations.

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Controlling and maintaining exposure of hydrophobic organic compounds in aquatic toxicity tests by passive dosing

Cited by 147 publications

References 32 publications

Dynamic Passive Dosing for Studying the Biotransformation of Hydrophobic Organic Chemicals: Microbial Degradation as an Example

Dynamic Passive Dosing for Studying the Biotransformation of Hydrophobic Organic Chemicals: Microbial Degradation as an Example

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

Aquatic toxicity tests with substances that are poorly soluble in water and consequences for environmental risk assessment

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