Determination of the dietary biomagnification of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane with the rainbow trout (Oncorhynchus mykiss)

Decamethylpentacyclosiloxane (D5) is a widely used, high-production volume personal care product with an octanol-water partition coefficient (log K OW ) of 8.09. Because of D5's high K OW and widespread use, it is subject to bioaccumulation assessments in many countries. The present study provides a compilation and an in-depth, independent review of bioaccumulation studies involving D5. The findings indicate that D5 exhibits depuration rates in fish and mammals that exceed those of extremely hydrophobic, nonbiotransformable substances; that D5 is subject to biotransformation in mammals and fish; that observed bioconcentration factors in fish range between 1040 L/kg and 4920 L/kg wet weight in laboratory studies using non-radiolabeled D5 and between 5900 L/kg and 13 700 L/kg wet weight in an experiment using C 14 radiolabeled D5; and that D5 was not observed to biomagnify in most laboratory experiments and field studies. Review of the available studies shows a high degree of internal consistency among findings from different studies and supports a broad comprehensive approach in bioaccumulation assessments that includes information from studies with a variety of designs and incorporates multiple bioaccumulation measures in addition to the K OW and bioconcentration factor. Environ

Section: Resultsmentioning

confidence: 99%

Bioaccumulation of decamethylpentacyclosiloxane (D5): A review

Gobas

Powell

Woodburn

et al. 2015

“…The BCF ww,fd represents steady‐state conditions; is specific to the lipid content of the fish for which the BCF is determined; and includes the effect of growth dilution. Some authors have calculated BCFs for nongrowing fish as conservative estimate of the BCF . The BCF for a nongrowing fish can be approximated (e.g., in absence of fish growth measurements) from the intercept of Equation as

B C {normalF}_{w w, f d} = k_{1} / true(k_{T} - normalβ true)

…”

Section: Theorymentioning

confidence: 99%

Deriving bioconcentration factors and somatic biotransformation rates from dietary bioaccumulation and depuration tests

Gobas

2016

The present study develops, applies, and tests a method for deriving empirical bioconcentration factors and somatic biotransformation rate constants from dietary bioaccumulation tests and simplified bioaccumulation experiments that measure depuration rates. In this approach, measurement of the chemical concentration in the water is not required. The method aims to improve bioaccumulation assessment, reduce cost and animal use, and shorten experiments. Environ Toxicol Chem 2016;35:2968-2976. © 2016 SETAC.

“…Accurately determining effect concentrations with algae may be difficult because of rapid volatilization of D5 in the static test system [42]. Nonetheless, 2 freshwater green algae (Pseudokirchneriella subcapitata and Scenedesmus subspicatus) tests in water treated with D5 at the limits of solubility resulted in no observable effects during the first 24 h, indicating no acute response [43]. Based on the currently available aqueous toxicity data, it can be concluded that concentrations of D5 in water up to the solubility limit of 17 mg/L do not appear to be associated with adverse effects in fish or other aquatic organisms.…”

Section: Risk From Aqueous Exposuresmentioning

confidence: 99%

“…Environ Toxicol Chem 34, 2015 organic carbon relative to its K OW (organic carbon partition coefficient ¼ 5.17). It is metabolized by many aquatic organisms at a moderate (0.007 d -1 ) to high (0.04 d À1 ) rate, as noted in studies with bolus administration of labeled 14 C-D5 in trout [43], which, when combined with low assimilation or transfer rates between species ($10% [44]), results in trophic dilution of D5 in aquatic food webs. This occurs despite the fact that the primary route of exposure to D5 for fish is through the diet and not bioconcentration via the water column.…”

Section: D5 Ecological Risk Characterizationmentioning

confidence: 99%

Characterization of ecological risks from environmental releases of decamethylcyclopentasiloxane (D5)

Fairbrother

Burton

Klaine

et al. 2015

Decamethylcyclopentasiloxane (D5) is used in personal care products and industrial applications. The authors summarize the risks to the environment from D5 based on multiple lines of evidence and conclude that it presents negligible risk. Laboratory and field studies show that D5 is not toxic to aquatic organisms or benthic invertebrates up to its solubility limit in water or porewater or its sorptive capacity in sediment. Comparison of lipid-normalized internal concentrations with measured concentrations in benthos indicates that field-collected organisms do not achieve toxic levels of D5 in their tissues, suggesting negligible risk. Exposure to D5 resulted in a slight reduction of root biomass in barley at test concentrations 2 orders of magnitude greater than measured D5 levels in biosolids-amended soils and more than twice as high as the maximum calculated sorptive capacity of the soil. No effects were observed in soil invertebrates exposed to similar concentrations, indicating that D5 poses a de minimis risk to the terrestrial environment. High rates of metabolism and elimination of D5 compared with uptake rates from food results in biodilution in the food web rather than biomagnification, culminating in de minimis risk to higher trophic level organisms via the food chain. A fugacity approach substantiates all conclusions that were made on a concentration basis. Environ Toxicol Chem 2015;34:2715-2722. © 2015 SETAC