Healthy Milk, Healthy Baby
Chemical Pollution and Mother's Milk
Chemicals: Cosmetics Identified in Breast Milk: Nitro Musks
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Natural animal musks have long been used as fragrances in beauty products, but because they are expensive to produce, scientists have developed synthetic chemicals to replace them. These synthetic compounds include nitro and non-nitro benzenes, indans and tetralins. Musk xylene, musk ketone and musk ambrette are three of the most commonly used synthetic nitro musk compounds. They are produced and used throughout the world in such scented products as detergents, soaps, lotions and perfumes. In 1988, an estimated 7,000 tons of musks were produced worldwide.1
Very little scientific research has been done on synthetic musk fragrances in the environment. Much of what research has been conducted is from Germany, and the subset of those studies that are available have shown that musks, and especially nitro musks, biodegrade very slowly, if not as slowly as PCBs and some of the other extremely persistent organic pollutants. Nitro musks have been shown to accumulate in fat and have been found in surface and wastewater, freshwater fish, shellfish and in human fat, blood and breast milk.2
Health Effects of Nitro Musks
No studies have determined nitro musks' toxicity to humans, but musk compounds have been shown to cause cancer in laboratory rodents. Studies have also demonstrated significant transfer of nitro musks from mother to developing rodent fetuses and infants through blood and mothers' milk. One study also reported significantly greater accumulation of nitro musks in the bodies of female rodents than in male rodents.3
Nitro Musks in the Body
Among the various nitro musks, musk xylene has been found in the highest concentrations in humans.4 Musk xylene concentrations found in 1995 in Germany in adult fat and breast milk were similar in range to PCBs and organochlorine pesticide levels measured in other studies, at 0.01 to 0.25 µg/g fat. In the same study, however, musk xylene concentrations in the fat of children and newborns were even higher, at up to 0.6 µg/g fat.5
Research suggests that the primary route of human exposure to nitro musks is not bioaccumulation through the food chain, as with many other organic pollutants, but absorption through the skin due to frequent use of products containing nitro musks. Recent studies have found no significant quantities of synthetic musks in human food sources other than freshwater fish. People who had elevated blood levels of nitro musks in a 1998 German study did not report eating any freshwater fish.6 Therefore, researchers concluded that people were likely directly exposed to these chemicals through consumer products.
To test the hypothesis that nitro musks may have entered subjects' blood through skin application of beauty products, one German study tested nitro musk levels in all the scented health and beauty products used at least three to four times a week by study participants with elevated blood nitro musk levels. The study found that high nitro musk levels in frequently used products were correlated with higher blood levels in subjects who reported using these products. All of the people with elevated nitro musk levels in this study were female, suggesting the possibility that women may be more highly exposed than men to nitro musks through their use of scented health and beauty products.
Controlling Exposure: Bans and Restrictions
Few nationwide bans and restrictions on nitro musks have been imposed because musks have only recently been identified in humans and in the environment and because little toxicity data is available on nitro musks.
However, some nations have taken steps to reduce exposures. For example, Japan has completely banned musk xylene; the United States in 1979 forbade companies from using musk xylene in cosmetic products that may be ingested; and the German detergent industry voluntarily removed musk xylene from production in 1993.7
Some individual companies also report that they are beginning to phase nitro musks out of their products. For example, The Body Shop states on its website that it currently sells products containing musk xylene, musk ketone and polycyclic musk, but that new products are being developed without these ingredients to replace existing products.8
Benchmarks and Exposure Limits for Nitro Musks
Because nitro musk contamination is a relatively newly understood phenomenon, no benchmarks or "safe" levels have been set for human exposure.
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Chlordane | DDT | Dieldrin, Aldrin and Endrin | Hexachlorobenzene | Hexachlorocyclohexane | Heptachlor | Mirex | Nitro Musks | Toxaphene | Dioxins and Furans | PBDEs | PCBs | Solvents | Lead, Mercury, Cadmium and Other Metals
1. Liebl, B., R. Mayer, S. Ommer, C. Sonnichsen, B. Koletzko, "Nitro Musks in Human Milk," Chemosphere 27(11) (2000): pp. 2253-2260; Suter-Eichenberger et al., "Bioaccumulation of Muxk Xylene (MX) in Developing and Adult Rats of Both Sexes," Chemosphere, vol. 36, no. 13 (1998): pp. 2747-2762.
3. Suter-Eichenbeger, R., H. Altorfer, W. Lichtensteiger, M. Schlumpf, "Bioaccumulation of Muxk Xylene (MX) in Developing and Adult Rats of Both Sexes," Chemosphere 36(13) (1998): pp. 2747-2762; Kafferlein, H.U., and J. Angerer, "Trends in the Musk Xylene Concentrations in Plasma Samples from the General Population from 1992/1993 to 1998 and the Relevance of Dermal Uptake," International Archives of Occupational and Environmental Health 74 (2001): pp. 470-476.
4. Ott, M., K. Failing, U. Lang, C. Schubring, H.J. Gent, S. Georgii, H. Brunn, "Contamination of Human Milk in Middle Hesse, Germany - A Cross-Sectional Study on the Changing Levels of Chlorinated Pesticides, PCB Congeners and Recent Levels of Nitro Musks," Chemosphere 38(1) (1999): pp. 13-32.
5. Liebl, B., R. Mayer, S. Ommer, C. Sonnichsen, B. Koletzko, "Nitro Musks in Human Milk," Chemosphere 27(11) (2000): pp. 2253-2260; Suter-Eichenberger et al., "Bioaccumulation of Muxk Xylene (MX) in Developing and Adult Rats of Both Sexes," Chemosphere, vol. 36, no. 13 (1998): pp. 2747-2762.
6. Kafferlein, H.U., and J. Angerer, "Trends in the Musk Xylene Concentrations in Plasma Samples from the General Population from 1992/1993 to 1998 and the Relevance of Dermal Uptake," International Archives of Occupational and Environmental Health 74 (2001): pp. 470-476.
last revised 3.25.05