Environmental and health protection agencies establish regulatory
levels for ECs in drinking water or permissible levels for ECs
in environmental discharges. The U.S. EPA developed a list of 126
priority pollutants (http://www.epa.gov/waterscience/methods/
pollutants.htm) that were to be regulated and monitored, particularly
in wastewater effluent, to protect freshwater in the United
States. Numerous compounds are on the EPA’s Contaminant
Candidate List (CCL), which is a list of unregulated environmental
contaminants that are to be monitored. Future regulation of
compounds on the CCL are to be based on their occurrence and
health effects (Richardson, 2003). The European Union (EU) water
framework established environmental quality standards (EQS) for
surface water with a list of 33 substances, most of which are organic
compounds. The EU directive is intended to help identify causes of
pollution and deal with the source of the pollutants (EU, 2008). The
U.S. EPA CCL and the EU directive are not designed to prioritize
research needs for the compounds based on their known occurrences
or toxicity. An analysis of trace pollutant and EC occurrence
in the freshwater environment and the corresponding acceptable
daily intakes (ADIs) allows us to better prioritize research needs
and regulation of chemical use