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

Fairbrother, Anne; Burton, G.A.; Klaine, Stephen J.; Powell, David E.; Staples, Charles A.; Mihaich, Ellen; Woodburn, Kent B.; Gobas, Frank A.P.C.

doi:10.1002/etc.3041

Cited by 25 publications

(48 citation statements)

References 34 publications

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“…Because D5's maximum fugacity (i.e., its vapor pressure) is 22.7 Pa at 25 °C, it is theoretically possible for D5 to cause nonpolar narcosis. However, nonpolar narcosis has not been observed or demonstrated in toxicity tests . Nonpolar narcosis is also unlikely to occur in the environment, because calculated activities and corresponding fugacities in biota are several orders of magnitude below values corresponding with nonpolar narcosis (Figures and ).…”

Section: Resultsmentioning

confidence: 99%

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Fugacity and activity analysis of the bioaccumulation and environmental risks of decamethylcyclopentasiloxane (D5)

Gobas

Kozerski

et al. 2015

Enviro Toxic and Chemistry

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As part of an initiative to evaluate commercial chemicals for their effects on human and environmental health, Canada recently evaluated decamethylcyclopentasiloxane (D5; CAS no. 541-02-06), a high-volume production chemical used in many personal care products. The evaluation illustrated the challenges encountered in environmental risk assessments and the need for the development of better tools to increase the weight of evidence in environmental risk assessments. The present study presents a new risk analysis method that applies thermodynamic principles of fugacity and activity to express the results of field monitoring and laboratory bioaccumulation and toxicity studies in a comprehensive risk analysis that can support risk assessments. Fugacity and activity ratios of D5 derived from bioaccumulation measures indicate that D5 does not biomagnify in food webs, likely because of biotransformation. The fugacity and activity analysis further demonstrates that reported no-observed-effect concentrations of D5 normally cannot occur in the environment. Observed fugacities and activities in the environment are, without exception, far below those corresponding with no observed effects, in many cases by several orders of magnitude. This analysis supports the conclusion of the Canadian Board of Review and the Minister of the Environment that D5 does not pose a danger to the environment. The present study further illustrates some of the limitations of a persistence-bioaccumulation-toxicity-type criteria-based risk assessment approach and discusses the merits of the fugacity and activity approach to increase the weight of evidence and consistency in environmental risk assessments of commercial chemicals.

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Section: Resultsmentioning

confidence: 99%

“…Available toxicity data for D5 have been compiled, reviewed, and discussed in Fairbrother et al . That study shows that there are no reported concentrations associated with observed toxic effects of D5 in any medium.…”

Section: Methodsmentioning

confidence: 99%

Fugacity and activity analysis of the bioaccumulation and environmental risks of decamethylcyclopentasiloxane (D5)

Gobas

Kozerski

et al. 2015

Enviro Toxic and Chemistry

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“…The goal of this review is to compile and review empirical studies of the bioaccumulation behavior of D5 with the aim of providing information that is useful in the categorization of D5 for bioaccumulation. Similar efforts addressing persistence, toxicity, and risk of D5 are discussed in accompanying studies in the present issue of Environmental Toxicology and Chemistry .…”

Section: Introductionmentioning

confidence: 86%

Bioaccumulation of decamethylpentacyclosiloxane (D5): A review

Gobas

Powell

Woodburn

et al. 2015

Enviro Toxic and Chemistry

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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

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“…38 For this reason, toxicity observed at concentrations in excess of the maximum sorptive capacity might have been due to "neat" cVMS. The maximum sorptive capacity of organic carbon (OC) may be calculated for a material as the product of the compound's water solubility (mg L −1 ) and its K OC value (L kg −1 OC).…”

Section: Bioconcentration and Toxicitymentioning

confidence: 99%

Bioconcentration and Aquatic Toxicity of Superhydrophobic Chemicals: A Modeling Case Study of Cyclic Volatile Methyl Siloxanes

Mackay

Powell

Woodburn

2015

Environ. Sci. Technol.

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Many chemicals in commerce are classified as "superhydrophobic", having log octanol-water partition coefficients (log KOW) approaching or exceeding 7. Examples include long-chain alkanes, halogenated aromatics, and cyclic volatile methylsiloxanes (cVMS). We show that superhydrophobic chemicals present unique assessment challenges because of their sparing solubility in water and difficulties in empirical determinations of bioconcentration factors (BCFs) and aquatic toxicity. Using cVMS as an example, BCFs are considerably lower than expected due to biotransformation. Reviewed aquatic toxicity test data for cVMS in a range of aquatic organisms show little or no toxic effects up to solubility limits in water and sediment. Explanations for this apparent lack of toxicity of cVMS, and by extension to other superhydrophobic chemicals, are explored using a conventional one-compartment uptake model to simulate bioconcentration and toxicity tests using an assumed baseline narcotic critical body residue (CBR) and a range of organism sizes. Because of the low aqueous concentrations, equilibration times are very long and BCFs are sensitive to even very slow rates of biotransformation. Most organisms fail to achieve the assumed CBR during feasible test durations even at the solubility limit. Regulatory evaluation of superhydrophobic substances requires specially designed test protocols addressing biotransformation and dietary uptake.

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

Cited by 25 publications

References 34 publications

Fugacity and activity analysis of the bioaccumulation and environmental risks of decamethylcyclopentasiloxane (D5)

Fugacity and activity analysis of the bioaccumulation and environmental risks of decamethylcyclopentasiloxane (D5)

Bioaccumulation of decamethylpentacyclosiloxane (D5): A review

Bioconcentration and Aquatic Toxicity of Superhydrophobic Chemicals: A Modeling Case Study of Cyclic Volatile Methyl Siloxanes

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