£ CDA Fact Sheet: Preliminary Regulatory Determinations for
the Second Drinking Water Contaminant Candidate List
(CCL 2)
EPA has drinking water regulations for more than 90 contaminants. To assess and address risks
posed by unregulated contaminants, EPA, in accordance with the Safe Drinking Water Act
(SDWA), identifies a list of contaminants which may require regulation in the future, and every
five years, EPA determines whether we should regulate at least five contaminants in drinking
water.
In February 2005, EPA published the second CCL of 51 contaminants. EPA has evaluated
available occurrence, exposure, and health effects information for CCL 2 contaminants. EPA is
announcing preliminary determinations for 11 of these 51 contaminants. EPA is requesting
comment on its preliminary determination that none of these 11 contaminants need to be
regulated in drinking water and is requesting comment from the public.
Questions and Answers
What is the drinking water CCL?
The drinking water CCL is the primary source of priority contaminants for conducting research
and making decisions about whether drinking water regulations are needed. The contaminants
on the list are known or anticipated to occur in public water systems. However, they are
currently unregulated with a national primary drinking water regulation.
How often is the CCL published?
The Safe Drinking Water Act directs EPA to publish a CCL every five years. We published the
first CCL of 60 contaminants in March 1998. We published the second CCL (CCL 2) in
February 2005. The second CCL carried forward 51 (of the original 60) unregulated
contaminants from the first CCL, including nine microbiological contaminants and 42 chemical
contaminants or contaminant groups (see Table 1).
What is a regulatory determination?
A regulatory determination is a formal decision on whether EPA should initiate a rulemaking
process to develop a national primary drinking water regulation for a specific contaminant. The
law requires that we make regulatory determinations for at least five contaminants from the most
recent CCL every five years.
In this notice, EPA announced its preliminary determinations for 11 contaminants listed on the
second CCL. EPA had sufficient health and occurrence information to make the determination
not to regulate boron, the dacthal mono- and di-acid degradates, l,l-dichloro-2,2-bis(p-
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chlorophenyl)ethylene (DDE), 1,3 -d ich loropropene (Telone), 2,4-d initrotoluene, 2,6-
dinitrotoluene, s-ethyl propyithiocarbamate (EPTC), fonofos, terbacil, or 1,1,2,2-
tetrach loroethane.
Occurrence information indicates that these 11 contaminants either appear to be nonexistent or
have low levels of occurrence at health levels of concern in public water systems and regulating
these contaminants does not present a meaningful opportunity for health risk reduction. In those
cases where low levels of occurrence exist, we are recommending that the Agency update the
current health advisories to reflect new information or to include the potential degradates. These
determinations are preliminary and the public can comment on the Agency’s decisions during the
60-day public comment period. We plan to notify the public of the final regulatory
determinations in 2008.
It is important to note that we are not limited to making regulatory determinations for only those
contaminants on the CCL. We can also decide to regulate other unregulated contaminants if
information becomes available, showing that a specific contaminant presents a public health risk.
What criteria does EPA consider in making regulatory determinations?
When making a determination to regulate, the law requires consideration of three areas:
• the potential adverse effects of the contaminant on the health of humans,
• the extent of contaminant occurrence in public drinking water, and
• whether regulation of the contaminant presents a meaningful opportunity for reducing
public health risks.
What is the Agency doing about perchiorate and methyl tertiary butyl ether (MTBE)?
The Agency continues to use the best available science on perchlorate to protect public health
and the environment. EPA has already developed a reference dose for perchiorate based on the
2005 recommendations by the National Academy of Sciences. EPA has also issued updated
guidance on how to use the reference dose in source water cleanup decisions. The Agency
believes additional information may be needed to more fully characterize perchlorate exposure
and determine whether it is appropriate to regulate perchiorate in drinking water (i.e., whether
setting a national primary drinking water standard would provide a meaningful opportunity to
reduce risk for people served by public water systems). The notice describes how the Agency is
considering FDA food data and CDC human exposure data to see if it can help us determine
whether it is appropriate to regulate perchiorate.
EPA is not making a regulatory determination for MTBE at this time because the Agency’s
health risk assessment has not been finalized. However, the notice summarizes some of the
available and relevant occurrence information for MTBE and provides an opportunity for states
to voluntarily submit finished drinking water occurrence data, information on the potential
impacts of MTBE contamination on public water systems, and any treatment information as
well.
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Do these Regulatoiy Determinations impose any requirements on public water systems?
No. The regulatory determinations on the CCL alone do not impose any requirements on public
water systems. However, if EPA decided to regulate a contaminant on the list in the future, then
public water systems would have to comply with the regulation.
Where can Ifind more information about this notice and the CCL 2 Regulatoiy
Determinations?
For information on the regulatory determinations for the second CCL, please visit
http://www . epa.gov/safewater/cclfrcz determ ine2 . html . For general information on drinking
water, please visit the EPA Safewater Web site at www.epa.gov/safewater or contact the Safe
Drinking Water Hotline at 1-800-426-4791. The Safe Drinking Water Hotline is open Monday
through Friday, excluding legal holidays, from 10:00 a.m. to 4:00 p.m., Eastern time.
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Table 1 - Drinking Water Contaminant Candidate List 2 (CCL 2 )
Microbial Contaminant Candidates
Adenoviruses
Aeromonas hydrophila
Caliciviruses
Coxsackieviruses
Cyanobacteria (blue-green algae), other freshwater algae, and their toxins
Echov iruses
Helicobacter pylon
Microsporidia (Enterocytozoon & Septata)
Mycobacterium avium intracel lulare (MAC)
Chemical Contaminant Candidates CASRN
1,1 ,2,2-tetrachloroethane 79-34-5
1 ,2,4-trimethylbenzene 95-63-6
1,1 -dichloroethane 75-34-3
1,1 -dichloropropene 563-58-6
I ,2-diphenylhydrazine 122-66-7
I ,3-dichloropropane 142-28-9
I ,3-dichloropropene 542-75-6
2,4,6-trichlorophenol 88-06-2
2,2-dich loropropane 594-20-7
2,4-dichlorophenol 120-83-2
2,4-dinitrophenol 51-28-5
2,4-dinitrotoluene 121-14-2
2,6-dinitrotoluene 606-20-2
2-methyl-Phenol (o-cresol) 95-48-7
Acetochlor 34256-82-1
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Chemical Contaminant Candidates CASRN
Alachior ESA & other acetanilide pesticide N/A
degradation products
Aluminum 7429-90-5
Boron 7440-42-8
Bromobenzene 108-86-1
DCPA mono-acid degradate 887-54-7
DCPA di-acid degradate 2136-79-0
DDE 72-55-9
Diazinon 333-41-5
Disulfoton 298-04-4
Diuron 330-54-1
EPTC (s-ethyl-dipropylthiocarbamate) 759-94-4
Fonofos 944-22-9
p-Isopropyltoluene (p-cymene) 99-87-6
Linuron 330-55-2
Methyl bromide 74-83-9
Methyl-t-butyl ether (MTBE) 1634-04-4
Metolachlor 51218-45-2
Molinate 2212-67-1
Nitrobenzene 98-95-3
Organotins N/A
Perchlorate 14797-73-0
Prometon 1610-18-0
RDX 121-82-4
Terbacil 5902-51-2
Terbufos 13071-79-9
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Chemical Contaminant Candidates CASRN
Triazines & degradation products of triazines including, but not limited to Cyanazine
21725-46-2 and atrazine-desethyl 6190-65-4
Vanadium 7440-62-2
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