revised final - Agency for Toxic Substances and Disease Registry ...

MERCURY 454
5. POTENTIAL FOR HUMAN EXPOSURE
science technicians, registered nurses, and machine operators. These estimates were derived from
observations of the actual use of mercury (97% of total estimate) and the use of trade-name products known
to contain mercury (3%). It is unknown how many of the potentially exposed workers were actually
exposed. Data from the NOES conducted by NIOSH from 1983 to 1986 was broken out by exposure to a
variety of mercury compounds (RTECS 1998). Estimates of the total numbers of all workers and women
workers potentially exposed are presented in Table 5-20. A total of 151,947 workers were potentially
exposed to mercury or various mercury compounds; 33% (50,468) of these workers were women.
Table 5-21 summarizes the calculated mercury absorption from air at various occupational exposure
guideline concentrations.
5.6 EXPOSURES OF CHILDREN
This section focuses on exposures from conception to maturity at 18 years in humans and briefly considers
potential pre-conception exposure to germ cells. Differences from adults in susceptibility to hazardous
substances are discussed in Section 2.6, Children’s Susceptibility.
Children are not small adults. A child’s exposure may differ from an adult’s exposure in many ways.
Children drink more fluids, eat more food, and breathe more air per kilogram of body weight, and have a
larger skin surface in proportion to their body volume. A child’s diet often differs from that of adults. The
developing human’s source of nutrition changes with age: from placental nourishment to breast milk or
formula to the diet of older children who eat more of certain types of foods than adults. A child’s behavior
and lifestyle also influence exposure. Children crawl on the floor; they put things in their mouths; they may
ingest inappropriate things such as dirt or paint chips; they spend more time outdoors. Children also are
closer to the ground, and they do not have the judgement of adults in avoiding hazards (NRC 1993).
Significant health risks, including numerous neuropathological and neurobehavioral effects, are associated
with prenatal exposure to methylmercury (Zelikoff et al. 1995). Fetuses and breast-fed infants may be
exposed to higher than background concentrations of mercury via maternal consumption of large amounts of
fish or marine mammals contaminated with mercury, via maternal exposure to mercury through dental
amalgams, via maternal use of consumer products containing mercury or various mercury compounds, and
via occupational exposure of the mother (Zelikoff et al. 1995). Fetuses can be exposed to mercury via
exposures of their mothers either before or during pregnancy; nursing infants can be exposed via
consumption of contaminated breast milk from mothers exposed via medical, domestic, or occupational