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Water Health Assessment
(Dover Township) Toms River, New Jersey
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Radiological Activity
Draft for Public Comment -- November 16, 1999
Radiological Activity
None of the distribution system (school) water samples from March 1996 exceeded the MCL for gross alpha activity of 15 pCi/I or the gross beta activity trigger level of 50 pCi/l (Table 9a). However, 13 schools exceeded a gross alpha level of 5 pCi/I (taking into account possible measurement error). This level triggers a regulatory analysis for radium-226 and radium-228. Estimates of combined radium (226 plus 228)
activity in these samples were all less than the MCL of 5 pCi/l. Four points of entry sampled in April 1996 (Route 70, Indian Head, Berkeley, and Parkway) reached or exceeded the MCL for gross alpha activity (Table 9b). The Route 70 and Indian Head points of entry approached or exceeded the combined radium drinking water standard of 5 pCi/I in those and subsequent samples (Table 9b). In response to these findings,
UWTR voluntarily reduced use of well #20 at the Indian Head point of entry beginning in the summer of 1996. Measurements from distribution system samples (hydrants) taken 'in July 1996 near the Berkeley and Route 70 points of entry showed relatively high gross alpha and combined radium activity (Table 9a). As the Holly, Brookside, and Windsor points of entry came on line in 1996, gross alpha activity was found to be low (Table 9b).
Subsequent quarterly sampling in 1996 and 1997 showed a consistent pattern of relatively higher gross alpha levels at points of entry in which Kirkwood-Cohansey wells provided a major proportion of water (Route 70, Berkeley, and Parkway). Wells in the Piney Point aquifer (well 37 at Holly, wells 15 and 43 at Brookside, wells 39 and 41 at Parkway, and well 40 at Windsor) and the deeper Potomac-Raritan-Magothy aquifer
(well 30 at Holly, wells 42 and 45 at Parkway) generally showed lower levels of gross alpha activity than the shallower wells tapping the Kirkwood-Cohansey aquifer.
The measurements of gross alpha activity were significantly higher than those found in historic compliance monitoring of the UWTR system. Furthermore, the combined radiurn-226 and radium-228 levels accounted for a smaller fraction of alpha activity than expected. Laboratory analysts noted that re-analyses of samples showed lower levels, and that samples analyzed close to collection time had the highest alpha activity.
Upon further study, NJDEP and NJDHSS determined that there was a short-lived alpha particle emitter, radium-224, that was contributing to the high gross alpha activities (Parsa, 1998). Since routine radiological testing typically involves long sample holding times before analysis, radium-224, whose half-life is approximately 3.5 days, decays before testing. This finding has led the NJDEP to re-examine required procedures for
the collection and analysis of samples for radiological activity from community water supplies.
With the U.S. Geological Survey, NJDEP has been studying the occurrence of gross alpha activity and radium species throughout New Jersey. Studies of the distribution of radium-226 and -228 (and more recent data of gross alpha activity using short holding times) indicate that radiological activity attributable to radium species is a problem that is not confined to the Dover Township area. Instead, it appears that radium-related
activity is elevated throughout the shallower aquifer systems of southern New Jersey and in parts of northern New Jersey (NJDEP, 1997).
Two wells and their corresponding point of entry were selected for detailed time-series monitoring for gross alpha activity in order to determine time variability over the course of a day and a week (Table 9d). The results show that the gross alpha activity levels were relatively stable over a day and a week.
Radiological activity results for the comparison samples are found in Table 9e. One of the four comparison wells samples exceeded the gross alpha activity trigger level of 5pCi/l. Radiological activity was very low in the commercial bottled water sample.
Radium exposure has been associated with increased risk of bone and paranasal sinus cancers in highly exposed workers (NRC, 1988; NRC, 1990). Few epidemiologic studies have examined the risk of childhood cancers with respect to radium in drinking water.
Radium in drinking water has been associated with increased bone cancer incidence in adolescents (Finkelstein and Krieger, 1996) and with leukemia incidence in adults but not children (Lyman et al., 1985). The epidemiologic evidence is insufficient to draw conclusions regarding the risk from radium in drinking water.
Uranium activity (for three isotopes: U-238, U-235, and U-234) was measured in April 1996 samples from the Indian Head point of entry and well 20, the Route 70 point of entry and well 3 1, and the Berkeley and Parkway points of entry (Table 9c). Combined uranium ranged from not detectable up to 1.5 pCi/l. Combined thorium activity (for three isotopes: Th-228, Th-230 and Th-232) was measured at 0.2 pCi/I in a sample from well 20.
There are no MCLs for thorium or uranium activity.
Radon test results from the Parkway point of entry and wells, the Windsor and Brookside points of entry, and wells at South Toms River and Berkeley ranged from 80 (plus or minus 10) to 410 (plus or minus 50) pCi/l. Normal ranges of radon gas in groundwater in southern New Jersey are generally in this range or higher. A USEPA proposed MCL of 300 pCi/L for radon in drinking water was published in 1991, but has not been finalized
because of the relatively modest role that radon from drinking water has relative to overall radon exposure. Radon gas exposure at high levels in underground mines is associated with increased risk of lung cancer; epideologic studies of radon exposure at the lower levels found in the indoor air of some homes (from radon gas infiltration of basements) also suggest an increase risk of lung cancer (Lubin and Boice, 1997; NRC, 1998; NRC, 1988).
No association was found between exposure to radon in indoor air and risk of childhood cancers (Lubin et al., 1998).
Ganima spectroscopy scans of samples from the South Toms River and Route 70 points of entry and wells revealed no evidence of contamination by gannna-emitting radionuclides generated by human activities.
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