4. Synthesis and critical evaluation
It is a challenge to evaluate the multitude of organic compounds
and breadth of literature on trace pollutants and ECs in the freshwater
environment. In this section, information for widely used and
reported trace pollutants and ECs are presented in three groups:
industrials (Table 1), pesticides (Table 2) and PPCPs (Table 3). The
rate of occurrence (frequency of detection) was compiled from the
literature along with the highest reported maximum and median or
mean concentrations (mg L1
) for surface water, groundwater, or
drinking water samples. Toxicity of the compound was also
compiled from the literature using an ADI (mg kg1
$day1
). The
previously reported ADIs were generally formulated from the
LOAEL and applied an uncertainty factor of 100 (Snyder et al., 2008).
Literature sources for detection frequency, concentrations, and
toxicity are provided in Tables 1e3.
When a concentration in the freshwater environment was
available along with the ADI, then a consumption rate posing health
risk (CRPHR) was computed for a 70 kg individual using the
following equation:
CRPHR ¼ ADI 70 kg
concentration 0:001
where CRPHR is a consumption rate (L$day1
) that represents an
exceedance of the ADI and therefore a health risk to a 70 kg individual,
ADI is measured in mg kg1
$day1
, concentration is
measured in mg L1
, and 0.001 is a unit conversion for mass in
numerator versus denominator. The CRPHR was computed for both
the maximum and average concentrations of the compound
reported in the literature. CRPHR computations are presented in
graphical form (Fig. 1) to allow for comparison of the risk posed by
maximum and average concentrations in the freshwater environment.
Fig. 1 shows the CRPHR at the maximum concentration as
a point and, when the median or mean was available, extends an
error bar to the CRPHR at the average concentration.