The detection frequencies of pharmaceutical compounds in
groundwater in this study were lower than the detection frequencies
observed in the national reconnaissance studies of groundwater
(Barnes et al., 2008a), and groundwater used for drinking-water
supplies (Focazio et al., 2008).
The national reconnaissance studies used the same laboratory (NWQL) and analytical methods for pharmaceutical compounds as used in this study, and for these
comparisons, the detection frequencies in the national reconnaissance
studies were calculated relative to the same MDLs as used in this
study. Of the 25 groundwater samples analyzed by Focazio et al.
(2008),
4 samples had detections of at least one pharmaceutical
compound at concentrations greater than or equal to the MDLs used
in this study. Of the 47 groundwater samples analyzed by Barnes et al.
(2008a)
Note that carbamazepine – the compound with the
highest detection frequency in this study and in Focazio et al. (2008)