This is the first
large-scale, systematic assessment of hormone
and pharmaceutical occurrence in groundwater used for drinking across
the United States. Samples from 1091 sites in Principal Aquifers representing
60% of the volume pumped for drinking-water supply had final data
for 21 hormones and 103 pharmaceuticals. At least one compound was
detected at 5.9% of 844 sites representing the resource used for public
supply across the entirety of 15 Principal Aquifers, and at 11.3%
of 247 sites representing the resource used for domestic supply over
subareas of nine Principal Aquifers. Of 34 compounds detected, one
plastics component (bisphenol A), three pharmaceuticals (carbamazepine,
sulfamethoxazole, and meprobamate), and the caffeine degradate 1,7-dimethylxanthine
were detected in more than 0.5% of samples. Hydrocortisone had a concentration
greater than a human-health benchmark at 1 site. Compounds with high
solubility and low K
oc were most likely
to be detected. Detections were most common in shallow wells with
a component of recent recharge, particularly in crystalline-rock and
mixed land-use settings. Results indicate vulnerability of groundwater
used for drinking water in the U.S. to contamination by these compounds
is generally limited, and exposure to these compounds at detected
concentrations is unlikely to have adverse effects on human health.
Percentage of basin-fill aquifer model grid cells in the Southwest Principal Aquifers study area that are predicted to exceed the relative background nitrate concentration, by percentage of agricultural and urban land use in the model grid cell ........... 48 12. Standardized importance scores for the prediction and confirmatory random forest classifiers of arsenic concentrations in basin-fill aquifers of the Southwest
In
2019, 254 samples were collected from five aquifer systems to
evaluate perfluoroalkyl and polyfluoroalkyl substance (PFAS) occurrence
in groundwater used as a source of drinking water in the eastern United
States. The samples were analyzed for 24 PFAS, major ions, nutrients,
trace elements, dissolved organic carbon (DOC), volatile organic compounds
(VOCs), pharmaceuticals, and tritium. Fourteen of the 24 PFAS were
detected in groundwater, with 60 and 20% of public-supply and domestic
wells, respectively, containing at least one PFAS detection. Concentrations
of tritium, chloride, sulfate, DOC, and manganese + iron; percent
urban land use within 500 m of the wells; and VOC and pharmaceutical
detection frequencies were significantly higher in samples containing
PFAS detections than in samples with no detections. Boosted regression
tree models that consider 57 chemical and land-use variables show
that tritium concentration, distance to the nearest fire-training
area, percentage of urban land use, and DOC and VOC concentrations
are the top five predictors of PFAS detections, consistent with the
hydrologic position, geochemistry, and land use being important controls
on PFAS occurrence in groundwater. Model results indicate that it
may be possible to predict PFAS detections in groundwater using existing
data sources.
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