Elsevier

Toxicology Letters

Volume 111, Issues 1–2, 20 December 1999, Pages 81-94
Toxicology Letters

Environmental risk assessment for the polycyclic musks, AHTN and HHCB: II. Effect assessment and risk characterisation

https://doi.org/10.1016/S0378-4274(99)00170-8Get rights and content

Abstract

Reports of the polycyclic musks AHTN and HHCB in surface water and fish, primarily in Europe, have prompted studies of their environmental effects. These effects then are used, along with the predicted environmental concentrations in a risk assessment according to the approach developed under European Union Regulation 793/93, in line with the Technical Guidance Document for risk assessment of new and existing chemicals. In 72-h studies with algae (Pseudokirchneriella subcapitata), NOECs were 0.374 mg/l (AHTN) and 0.201 mg/ l (HHCB). In 21-day reproductive tests with daphnia (Daphnia magna) NOECs were 0.196 (AHTN) and 0.111 mg/l (HHCB). In 21-day growth tests with bluegill sunfish (Lepomis macrochirus), NOECs were 0.067 (AHTN) and 0.068 mg/l (HHCB). And, finally 35-day early life stage tests with fathead minnows (Pimephales promelas) resulted in NOECs of 0.035 (AHTN) and 0.068 mg/l (HHCB). These results lead to Predicted No Effect Concentrations (PNEC) of 3.5 μg/l (AHTN) and 6.8 μg/l (HHCB) for aquatic organisms. For the soil compartment, 8-week studies with earthworms (Eisenia fetida) resulted in NOECs of 105 (AHTN) and 45 mg/kg (HHCB) and 4-week studies with springtails (Folsomia candida) resulted in a NOECs of 45 mg/kg for both substances. These values lead to a PNEC of 0.32 mg/kg dw for both materials. Using mammalian studies, PNECs for fish or worm eating predators of 10 mg/kg fw (AHTN) and 100 mg/kg fw (HHCB) can be derived. For sediment dwelling organisms, PNECs were derived by equilibrium partitioning using the aquatic PNECs. Comparing PNECs with the measured or predicted environmental exposures leads to risk characterisation ratios as follows: aquatic species: AHTN 0.086, HHCB 0.074; sediment organisms: AHTN 0.44, HHCB 0.064; soil organisms: AHTN 0.091, HHCB 0.10; fish eating predators: AHTN 0.012, HHCB 0.001; worm eating predators: AHTN 0.007, HHCB 0.001.

Introduction

The polycyclic musks 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) and 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-γ-2-benzopyran (HHCB) are widely used as fragrances ingredients in detergents and other household products. This, combined with high log Kow values and lack of ready biodegradability, has resulted in their widespread occurrence in the environment (Balk and Ford, 1999). AHTN and HHCB together represent about 95% of the total market volume for the class of fragrance ingredients known as the polycyclic musks.

In view of reported levels in surface water and fish primarily in Europe, the Research Institute of Fragrance Materials (RIFM) initiated an environmental risk evaluation according to the approach developed under European Union Regulation 793/93, in line with the Technical Guidance Document for risk assessment of new and existing chemicals (EU-TGD; EC, 1996). In an environmental risk assessment, the environmental exposure is compared to data on environmental effects. The exposure of the environment to AHTN and HHCB is presented in a separate paper (Balk and Ford, 1999, part I) in this issue.

Because the reported occurrences of these materials are in water and fish, these were considered the most important issues to address. However, these occurrences along with measured values in sludge, allow prediction of exposures of soil and sediment-dwelling organisms and of predators feeding on these organisms or on fish. Thus, the risks for these endpoints are also addressed.

This paper reports on the environmental effects of the AHTN and HHCB on the basis of a series of ecotoxicity studies on both materials that have been carried out on behalf of RIFM, and presents the environmental risk assessment.

Section snippets

Materials and methods

The structure and some relevant characteristics of AHTN and HHCB are given in Table 1.

Because of the low water solubilities of AHTN and HHCB, it was necessary in the aquatic toxicity tests described below to prepare stock solutions using DMF as a solvent and Tween 80 as a dispersant or using triethylene glycol as a solvent. These stock solutions were then diluted to reach the desired concentrations in the tests. The residual level of the solvent in the test vessel was always below the maximum

Toxicity test results for AHTN

The results for AHTN are summarised in Table 2 and Table 4.

Discussion

In the EU-TGD quantitative structure-activity relations (QSAR) are given for baseline or minimum toxicity for chronic endpoints for fish (Brachydanio rerio/P. promelas), D. magna and Selenastrum capricornutum. For fish, these QSARs predict the prolonged LC50 correctly and the predicted prolonged NOEC is below the experimental results by factors of 3–10. For D. magna the predicted 16-day-NOEC is too low by a factor of 50, whereas the EC50 for algae is overestimated by a factor of 15–35. In

Conclusions

The polycyclic musks AHTN and HHCB are less toxic to aquatic organisms than expected on the basis of ‘minimum toxicity’ as predicted by QSAR methods. The NOEC for fish, daphnia and algae range from 35 to 280 μg/l for AHTN and from 70 to 200 μg/l for HHCB. Fish are slightly more sensitive than the other species. Fish embryo development is affected at concentrations just below and at the lethal level. The PNECs derived for aquatic organisms are 3.5 and 7 μg/l for AHTN and HHCB, respectively.

The

Acknowledgements

Results of an initial risk assessment for AHTN and HHCB have been discussed in a task force consisting of T.J. van Bergen, H.-D. Gaisser and J.D. Middleton of NEA, E.J. van de Plassche and P.T.J. van de Zandt (National Institute of Public Health and the Environment (RIVM) and the authors.

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