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187
6. POTENTIAL FOR HUMAN EXPOSURE
samples were also collected during two periods from individuals living in Colorado least 16 km from the
RFETS. Mean
239
Pu excretion rates of 1.1x10
-6
and 8.5x10
-7
Bq/day (3.0x10
-5
and 2.3x10
-5
piCi/day)
were reported for the entire Rocky Flats group and the background group, respectively. Analysis
indicated that these data were not statistically significantly different. Measured levels of
239
Pu in urine
from the Rocky Flats group were within the range reported for background levels (Ibrahim et al. 1999).
Bolotov et al. (2003) reported
239
Pu concentrations in human hair ranging from 0.90 to 3.0 Bq/kg (20–
80 pCi/kg) in samples from the area of the heavily damaged Semipalatinsk nuclear bomb test site region
in Russia.
239
Pu concentrations in human gall stones collected from three individuals from Minsk,
Belarus were 0.28–0.53 Bq/kg (7.5–14 pCi/kg); gall stones from another individual in Krakow, Poland
contained <0.05 Bq/kg (<1 pCi/kg)
239
Pu (Bolotov et al. 2003).
Yamamoto et al. (2008a) reported plutonium concentrations human tissue samples, including bone
(vertebra), lungs, liver, and kidneys, collected during 2000–2002 at autopsy from nine residents who died
in some settlements and in Semipalatinsk City around the Semipalatinsk Nuclear Test Site.
239,240
Pu
239
Pu
concentrations in four bone (vertebra) samples ranged from 0.049 to 0.13 mBq/g ashed weight.
concentrations in six kidney samples ranged from 0.023 to 0.25 mBq/g ashed weight;
240
Pu was not
detected in these kidney samples. In the nine liver samples
239
Pu and
240
Pu concentrations were 0.39–
4.83 and 0.2–2.74 mBq/g ashed weight, respectively. In the nine lung samples
239
Pu and
240
Pu
concentrations ranged from 0.044 to 1.56 and from not detected to 1.83 mBq/g ashed weight,
respectively. In addition, bone samples, mainly vertebral bone, were collected from 23 deceased residents
of this area.
239,240
Pu activity in these bone samples ranged from 0.020 to 0.107 mBq/g ashed weight, with
a mean of 0.46 mBq/g ash weight. Yamamoto et al. (2008a) reported that the
239,240
Pu levels in bone,
lung, and liver samples in this study did not seem to be largely different from ranges found for human
tissue samples for residents from other countries that were due solely to global fallout during the 1970s–
1980s. Human tissue autopsy samples were obtained for the period of 1975–2003 from non-
occupationally exposed residents of Ozyorsk, Russia in the vicinity of the Mayak nuclear facility.
Since
the early 1950s, the plutonium body burden in the Ozyorsk population was shown to grow at a nearly
constant rate and total accumulation amounted to 5.8 Bq at 35 years after the construction of the plant in
the city
(Suslova et al. 2007).
PLUTONIUM
188
6. POTENTIAL FOR HUMAN EXPOSURE
6.6 EXPOSURES OF CHILDREN
This section focuses on exposures from conception to maturity at 18 years in humans. Differences from
adults in susceptibility to hazardous substances are discussed in Section 3.7, 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, 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, put things in their mouths,
sometimes eat inappropriate things (such as dirt or paint chips), and spend more time outdoors. Children
also are closer to the ground, and they do not use the judgment of adults to avoid hazards (NRC 1993).
Children would be exposed to plutonium from fallout by similar routes are adults, such as ingestion of
food and water and breathing ambient air. However, levels would generally be low for children not living
near areas with known plutonium contamination (e.g., areas where nuclear accidents or former plutonium
processing plants). Limited data on exposures of children to plutonium were located.
Compared to adults, the potential for plutonium exposure is greater for children who consume foods (e.g.,
milk, grains) produced in areas with elevated concentrations of plutonium in the soil and for children with
elevated concentrations of plutonium in their drinking water. Children are more likely to be exposed to
plutonium in dairy products produced in contaminated areas.
O’Donnell et al. (1997) reported an average
239,240
Pu concentration in permanent teeth collected from
children within the United Kingdom and Republic of Ireland of 5 mBq/kg (0.1 pCi/kg) ash weight.
239,240
Pu concentrations decreased with increasing distance from Sellafield; at 0–50, 50–150, and
>150 miles from Sellafield, average
239,240
Pu concentrations were 7.1, 5.0, and 3.0 mBq/kg (0.20, 0.10,
and 0.08 pCi/kg) ash weight, respectively. These levels are not considered to present a radiological
hazard (O’Donnell et al. 1997). Urine collected during a 24-hour period from 17 school-aged children in
North London contained 3.5 µBq/day of
239
Pu (Priest et al. 1999).
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