A recent article by Luckenbach and Epel (2005) on in vitro observations of inhibitory properties exhibited by certain nitromusk and polycyclic musk fragrance ingredients on mussel cells raised some concerns regarding potential environmental risks and safety to humans that may be associated with nitromusk and polycyclic musk compounds. The Research Institute for Fragrance Materials would like to address several points that may help readers more clearly understand the meaning and context of the reported research.
The tonnages of musk compounds reported by Luckenbach and Epel (2005) in their article (7,000-8,000 tons) are higher than the industry-reported global tonnage of these materials. From 1995 to 2000, the total worldwide usage declined from 300 tons to 200 tons for musk xylene and musk ketone combined. The 2000 worldwide use of polycyclic musks is approximately 4,000 tons.
Measured concentrations of these compounds in the environment are less than the effects concentrations reported by Luckenbach and Epel (2005). In a review of measured environmental concentrations, Rimkus (1999) stated that the highest reported measurement of hexahydro-hexamethyl-cyclopenta ([gamma])-2-benzopyran (HHCB) in surface water was 12.5[micro]g/L (0.048 [micro]M). The I[C.sub.50] (concentration that inhibits 50%) reported for polycyclic musks was 2.34 [micro]M. Overall, measured environmental concentrations were 2-6 orders of magnitude lower than the effects concentrations reported by Luckenbach and Epel (2005).
The data reported by Luckenbach and Epel (2005) reflect a method under development. There are many steps between the observation of an in vitro effect and effects on whole organisms, ecosystems, and humans. In vivo studies in mussels and studies linking mussel gill tissue to undefined tissues in mammals and humans are some of the research necessary to conclude that these higher level effects may exist. These effects would then need to be placed into a risk-based context by comparing them to exposure concentrations.
The safety of nitromusk and polycyclic musk compounds for humans has been extensively tested and affirmed by numerous regulatory agencies and academic scientists around the world [Scientific Committee on Cosmetic Products and Non-Food Products (SCCNFP) 2002a, 2002b]. The trace environmental levels of the musks continue to be investigated, and environmental safety and monitoring studies are ongoing so that the public can be assured of their safety.
Regarding the environmental effects of synthetic musks, the I[C.sub.10] (concentration that inhibits 10%) values should be compared to no observed effect concentrations (NOECs). The I[C.sub.10] values of the synthetic musks are around the level of the lowest in vivo NOECs observed for aquatic organisms. …