Synthetic fragrances perfume lake sediments
Production of these persistent compounds has doubled since the 1990s, and scientists are concerned about sublethal effects.
The scent of perfume behind the ears has timeless allure, but perfume raises scientific eyebrows when it persists in the environment. Research published today on ES&T’s Research ASAP website (DOI: 10.1021/es060134y) documents, for the first time, a historical profile of synthetic-fragrance concentrations in lake sediment. The results show a dramatic rise in environmental exposure over the past 15 years—a potential concern if these persistent contaminants turn out to have biological effects, experts say.
Synthetic musk fragrances, far cheaper than and chemically dissimilar to the natural fragrance obtained from musk deer and musk ox, are found in common household detergents, soaps, shampoos, and cosmetics, says Keri Hornbuckle, an environmental engineer at the University of Iowa and a coauthor of the study. They have also been detected in human fat and breast milk.
U.S. manufacturers used 6500 t of synthetic musks in 2000, the last year for which data are available. The U.S. EPA lists HHCB (Galaxolide), the most common fragrance compound, as a high-production-volume chemical—>1 million lb/year are imported or produced. In addition, synthetic fragrances persist in the environment, accumulate in animals, and have an affinity for fat—all traits of persistent organic pollutants. These properties, combined with the sheer volume used, worry researchers, who have begun to track the environmental fate and biological impacts of synthetic fragrances, Hornbuckle says.
Hornbuckle and her colleagues dated two sediment cores from Lake Erie and Lake Ontario and analyzed the concentrations of five polycyclic and two nitro musk fragrances. They found that HHCB concentrations actually declined slightly from 1979 to 1990; however, from 1990 to 2003, levels of HHCB doubled in only 8 years. The dry weight concentrations of fragrances in sediment are in the parts-per-million range.
The concentration of HHCB over time mirrored the trends in U.S. consumption of all fragrances, including synthetic musks, terpenes, and other compounds, levels of which have also risen significantly in the past decade, Hornbuckle says. Industry would not provide the researchers with consumption data for individual fragrances.
“This research indicates that production is increasing over time, and that is reflected in the concentrations of these musks that are accumulating in sediment,” says Chris Metcalfe, an ecotoxicologist at Trent University (Canada).
Research on Lake Michigan shows that sewers serve as the primary conduit for fragrances, which wash down the drain after being applied to skin, hair, and clothing, Hornbuckle says. She has also detected fragrances in rural air at levels higher than those of the most commonly used pesticides.
“Thus far, the European Chemicals Bureau has concluded that HHCB and AHTN [Tonalide, a polycyclic musk] are not PBTs [persistent, bioaccumulative, and toxic substances], and the European Scientific Committee for Cosmetics and Non-Food Products has affirmed their continued safe use in consumer products,” says Dan Salvito, an environmental scientist at the Research Institute for Fragrance Materials, an industry association.
However, Europe has phased out nitro musks over concerns that they are carcinogenic and endocrine-disrupting, says Roland Kallenborn, an environmental chemist at the University Centre in Svalbard (UNIS; Norway). Recent studies are indicating that polycyclic musks may have sublethal effects in fish; they bind to estrogen receptors and act as an antagonist to vitellogenin, an egg yolk precursor protein, Metcalfe says.
