Environmental risk assessment for the polycyclic musks, AHTN and HHCB: II. Effect assessment and risk characterisation
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.
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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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The human safety of the polycyclic musks AHTN and HHCB in fragrances—a review
Dt. Lebensm.-Rdsch
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