Public Health Assessment Public Comment Release
Ward Transformer NPL Site
Mercury
The form of mercury that builds up in fish is methylmercury, an organic (carbon-containing)
form of mercury. High levels of methylmercury can result in brain and kidney damage and can
be especially harmful to developing children exposed either prenatally or after birth. The highest
level of
mercury measured in
fish filets downstream of
the Ward Transformer site is
1.1 mg/kg,
only slightly higher than FDA's action level of 1 mg/kg for commercial seafood. The estimated
child dose of 0.001 mg/kg/day is about the same as the dose of 0.0013 mg/kg/day that had no
adverse health effects in human epidemiologic studies; however, other studies have suggested
developmental effects may occur at similar doses [19]. Mercury is a widespread contaminant and
was not known to be
used at
the Ward Transformer company. Although a
slightly increased risk
for health effects is possible from exposure to mercury through this pathway, Ward Transformer
is unlikely to have contributed significantly to this risk.
Aroclor 1260
Aroclor 1260 consists of a mixture of PCBs. The estimated intake for children eating fish caught
recreationally is 0.003 mg/kg/day and for adults is 0.0009 mg/kg/day. The chronic-duration
minimal risk level derives from an animal study in which Rhesus monkeys fed as little as 0.005
mg/kg/day Aroclor 1254 for 23 months exhibited decreased antibody response and some mild
clinical manifestations of toxicity (eyelid and toe/fingernail changes) [5]. An intermediate-
duration minimal risk level (0.00003 mg/kg/day) is derived from an animal study in which
monkeys fed as little as 0.0075 mg/kg/day for 20 weeks exhibited decrements in learning and
neurobehavioral performance. For both children and adults, estimated doses for recreational
consumption of
fish are within an
order of
magnitude of
the lowest observed adverse effect
levels observed in these studies. If children and adults ate enough fish, adverse health effects
could result. The most likely health effects would be mild immunologic or neurologic changes.
The excess cancer risk associated with eating filets from recreationally caught fish with the
average Aroclor 1260 concentration listed in Table 2 was estimated, assuming daily and
continual exposure over a 25-year period. The estimated theoretical excess cancer risk is about 7
in 10,000; ATSDR considers this a low-to-moderate increased risk for cancer. The actual risk of
developing cancer depends on many factors, including actual consumption, actual contaminant
levels in the fish consumed, genetics, lifestyle, and other environmental factors.
Update of Aroclor 1260 Analysis Based on November 2003 Fish Sampling
In November 2003, additional fish samples were collected further downstream from the May
2003 sampling locations. Fish were collected from the lower portion of Brier Creek Reservoir,
from Brier Creek downstream from Brier Creek Reservoir and from three different areas in Lake
Crabtree. Whole body samples were collected from Brier Creek, and both whole body and filet
samples were collected from Brier Creek Reservoir and from Lake Crabtree. Filets had skin left
on except for catfish filet samples which had the skin removed. The November fish samples were
analyzed only for PCBs, PCB congeners, and dioxins/furans. ATSDR evaluated only the fish
filet results, since it is assumed recreational fishers in the area do not eat the whole fish. A
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