United States
Environmental Protection
\r ^1	Agency
Office of Water
June 2019
2016-2017 Biosolids Biennial Review
The Clean Water Act (CWA) requires EPA to review
federal biosolids (sewage sludge) standards every
two years to identify additional toxic pollutants that
occur in biosolids and set regulations for those
pollutants if sufficient scientific evidence shows they
may harm human health or the environment. The
biennial review process is intended to fulfil the CWA
requirement to identify additional pollutants that
occur in biosolids.
During the 2016-2017 biennial review process, the
EPA collected and reviewed publicly available
information on occurrence, fate and transport in the
environment, and human health and ecological
effects for pollutants that (1) have been identified in
the Targeted National Sewage Sludge Survey (TNSSS;
U.S. EPA, 2009), or in the open literature as having
been found in biosolids; and (2) have not been
previously regulated or evaluated (e.g., as
potentially causing harm to humans or the
environment) in biosolids.
Results of the 2016-2017 Biennial Review
Thirty-two new journal articles were identified as
providing relevant data for chemical pollutants that
may occur in U.S. biosolids. Review of these articles
identified 28 new chemicals in biosolids: seven
polybrominated diphenyl ethers (PBDEs); nine
parabens and metabolites; five brominated flame
retardants (BFRs); three other flame retardants; two
perfluoroalkyl substances (PFASs); and two triclosan
transformation products. These articles also
identified new data for 31 chemicals previously
identified in biosolids. Concentration data in
biosolids were found for all 28 new chemicals and
for two chemicals identified in a previous biennial
review (diclofenac and tonalide). Human health
toxicity values were found for three of the new
chemicals (benzoic acid; 2,4-dichlorophenol; and
hexabromobenzene) and two previously identified
chemicals, perfluorooctanoate (PFOA) and
perfluorooctanesulfonate (PFOS). ECOTOXicology
knowledgebase (ECOTOX; U.S. EPA, 2018d) records
were found for 17 of the newly identified chemicals
and 26 of the previously identified chemicals.
Physical-chemical properties were identified for 22
of the new chemicals and 20 of the chemicals
previously identified in biosolids; and
bioconcentration or bioaccumulation factors were
identified for 23 of the new chemicals (11 in
terrestrial systems and 13 in aquatic; there was one
chemical with both) and 24 of the previously
identified chemicals.
In addition, six articles were identified as providing
relevant data for microbial pollutants that may occur
in biosolids. Review of these articles identified no
new microbial pollutants in biosolids. Data were
found for seven previously identified microbial
pollutants: Cryptosporidium spp., Giardia spp.,
antibiotic resistance genes (ARGs)/antibiotic
resistant bacteria (AR bacteria), Salmonella,
Escherichia coli, human norovirus, and human
Addressing the uncertainty around potential risk for
pollutants identified in biosolids is the top priority
for the EPA's Biosolids Program. The EPA has made
significant progress in developing the tools needed
to assess potential risk and the Agency intends to
analyze the data gleaned from the 2016-2017
biennial review process to determine whether it is