Executive Summary
Human Health
HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-benzopyran and related isomers) is a member of a group of substances used in fragrances and known collectively as the polycyclic musks. Because it is a highly viscous liquid, it is sold fluidised as an approximately 65% solution.
HHCB is used to make a fragrance long lasting and have a positive technical effect on its balance bringing the initial and residual smell into harmony.
HHCB is produced in one plant in the UK in an annual volume of 1000 to 5000 tonnes and is transported to Ireland for dilution to the commercial product.
It is used as an ingredient in commercial preparations intended to be used as fragrances in a wide variety of consumer products such as perfumes, cosmetics, household and laundry cleaning products and air fresheners. These commercial preparations are not sold retail. The level of HHCB in such preparations is typically at a level of several percent. The principal exposure to HHCB from household products can be considered to be via the skin.
The relative volume of use in household products versus perfumes, cosmetics, etc. is not known although the majority can be assumed to be used in household products based on the relative volume of sales of such products.
Environmental
To be completed.
Human health
HHCB has a low acute toxicity either by the oral or dermal route (LD50 values >3000 mg/kg). Inhalation exposure has been estimated to be negligible relative to dermal.
HHCB is not a skin or eye irritant and shows no phototoxicity potential on humans at concentrations significantly higher than would be encountered from the use of fragranced consumer products. There is no significant evidence either from animal or human studies of potential for dermal sensitisation. HHCB shows no photosensitisation potential on humans at concentrations significantly higher than would be encountered from the use of fragranced consumer products.
In a 90-day study in rats, there were no adverse effects at the highest dose tested, 150 mg/kg bw/day.
There were no indications of effects on fertility or the developing foetus at levels as high as 50 mg/kg bw/day.
There were no effects on rat pups exposed via the milk during nursing to levels of HHCB over 100 times the maximum level found in human milk samples.
HHCB is a non-genotoxic substance. The mutagenicity data and the repeated dose studies with HHCB do not indicate a concern with regard to carcinogenicity nor does HHCB possess any structural features that would raise a concern.
In the unlikely event of maximum exposures from direct and indirect skin contact as well as from the oral route via dishware residues, the estimated exposure to HHCB from its use in household cleaning products of 0.07 µg/kg bw/day. Comparison of this exposure to the NOAEL indicates a margin of safety of at least 350,000 and supports the conclusion that there is no significant risk to human health from exposure to HHCB as used in household cleaning products.
Environment
The polycyclic musks AHTN and HHCB are used as fragrance ingredients in consumer products like cosmetics and detergents and cleaning agents. They are important ingredients in fragrances because of their typical musky scent and their fixative properties.
Over the last decade synthetic musks have attracted the attention of environmental researchers due to their presence in environmental samples and human mother’s milk. As a reaction various risk assessments were carried out showing the risks were generally of low concern.
In the past decade the use volume of these substances in detergents and cleaning agents is declining, from circa 3300 tons in 1992 to 1800 tons in 2000. In household cleaning products, complex perfume-mixtures containing polycyclic musks are often purchased as such from the fragrance compounders and are used in the different formulations. Therefore, HERA was not able to come to representative volume data on use by the formulator companies.
The current risk assessment is made along the lines set out by the HERA methodology. The standard level risk assessment triggered a higher-tier approach to refine the risk assessment for the soil and sediment compartments. Using the more realistic monitoring data instead of the modelling approach, the environmental risk assessment for AHTN and HHCB shows that (1) sufficient data are available to assess the environmental risks; (2) the assessment can be based on measured concentrations in the northern region of the EU; (3) risk ratios are generally below 1; (4) however, for sediment organisms living in areas contaminated with a high effluent load, the risk ratios may be above 1. However, it should be remarked that the uncertainty around the toxicity to sediment organisms is high which is incorporated as an additional factor in the risk ratios.
Monitoring data are available for the northern region of the EU, but it is not known whether they are also representative for the southern European countries. An analysis was made of the regional variation of the use of AHTN and HHCB and of the trends in time. For this risk assessment, as a worst case, it was assumed, as a ‘worst case’, that the consumer use in southern European areas was 5 to 7 times above the use in northern Europe. The Berlin area was recognised as an area where sediment organisms may be at risk due to the combination of high loaded effluents and an extremely low dilution factor. The report includes an analysis of the uncertainties in the risk characterisation. As a follow-up, a large-scale programme was launched recently to sample sewage treatment plants and sediment in a number of southern European countries and in Berlin. Moreover, toxicity studies with sediment organisms are carried out to refine the risk assessments for these organisms.
A human risk assessment document was also developed within the scope of the HERA project. The preparation of these HERA risk assessments ran in parallel to the risk assessments for AHTN and HHCB in the context of the EU Existing Chemicals Programme.
Hera Comments
This updated version 2.0 of the HERA Risk Assessment takes account of comments from the External advisory Panel on Environmental and Human Risk Assessment parts.