Synthetic Musks 189
In recent years, bioaccumulation of various synthetic musks has increased to
the point that they are now considered to be major emerging pollutants by
environmental biologists around the globe, due to their long‐term persistence
in the environment and hazardous potential to ecosystems, even at fentomolar
concentrations. This is consistent with increased US use of fragrance chemi
cals in consumer products [73]. The synthetic musks are widespread environ
mental contaminants, particularly in freshwater and marine ecosystems
[72–76]. They have been measured in rivers, lakes, sediment, soil, sewage
sludge, and effluent from wastewater treatment plants in Canada, the USA, the
UK, and elsewhere in Europe [67]. Synthetic musk compounds have also been
detected in outdoor air [67] and indoor air due to their use in numerous con
sumer products. Studies in Europe, North America, and Japan have reported
bioaccumulation of synthetic musks in a wide range of aquatic wildlife species
including cetaceans, sharks, fish, crustaceans, and shellfish [69]. Nitromusks
and polycylic musks have also been found in human blood, adipose (fat) tissue,
and breast milk [67–70]. Many of the polycyclic and nitro musks are listed on
the US EPA’s Toxic Substances Control Act (TSCA) Inventory (TSCA, 2003).
The use of musk xylene and musk ketone in cosmetics is now restricted under
the EU Cosmetics Directive, due to their tendency to build up in the
environment.
How Do Synthetic Musks Get Into the Food Chain?
Widespread use of synthetic musks in consumer products results in large
amounts of these chemicals being washed down the drain after being applied to
skin, hair, and clothing. These chemicals enter water drainage, sewage, water
treatment plants, and wastewater systems, and then find their way into the
aquatic environment [67–72}. Once in the aquatic environment, synthetic
musks can enter the food chain, being taken up by wildlife such as fish and
shellfish. Following wastewater treatment, sewage sludge is digested via a reme
diation process, dewatered, and then the resulting solid waste is commonly
disseminated onto agricultural land. Synthetic musks in the sludge that have not
been degraded during digestion are therefore introduced to the terrestrial eco
system via the soil [75]. Most alarming is that because of their use in so many
consumer products, musks can also escape into air and dust, potentially enter
ing a pregnant woman’s system or a young child’s body during critical times of
brain development [2,3,75]. A simple wastewater system is shown in Figure 7.5.
How Are People Exposed to Synthetic Musks?
The main exposure route for most of the synthetic chemicals found in per
fumes, including musks, is through the skin (dermal absorption) as they are
applied directly onto the skin [67,76]. Absorption through the skin is also
