I’ll be the first to admit that this topic is one that puts
most people to sleep. But for the
regulatory geeks among us, it can be an interesting process, full of nuance and
surprise. OK, maybe that’s a bit much,
but it’s definitely an important process that it’s good for everyone in the
drinking water business to have some understanding of, so let’s dive in.
Drinking water regulations come primarily from two levels of
government. Regulation at the Federal level come through the United States
Environmental Protection Agency (US EPA or just EPA), and at the state level
through the California Dept of Public Health. Since federal regulations
generally trump state regulations, we'll start by going over the regulatory
process for the US EPA, and save the
California
process for the next blog post. EPA drinking water regulations become
PrimaryDrinking Water Standards that are applicable to everyone in all 50 states, with
certain exceptions. Currently, there are Primary Drinking Water Standards for
90 contaminants. EPA also develops secondary drinking water standards, but
these are recommendations that states may choose to enforce as they see fit.
The
Safe Drinking Water Act includes a process that EPA must follow to identify
and list unregulated contaminants, which may require a national drinking water
regulation in the future. EPA must periodically publish this list of
contaminants, called the
Contaminant Candidate List or
CCL,
and decide whether to regulate at least five or more contaminants on the
list. This is called 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 standard for a specific contaminant. When making a determination to
regulate, the Safe Drinking Water Act requires consideration of three criteria:
- the
potential adverse effects of the contaminant on the health of humans,
- the
frequency and level of contaminant occurrence in public drinking water
systems, and
- whether
regulation of the contaminant presents a meaningful opportunity for
reducing public health risks 4
The Third Contaminant Candidate List was finalized by the
EPA on October 9, 2009. It
contains 104 chemicals or chemical groups, and 12 microbiological contaminants.
The EPA started with 7,500 potential contaminants selected from pesticides,
disinfection byproducts, chemicals used in commerce, waterborne pathogens,
pharmaceuticals, biological toxins, and other sources. Contaminants were chosen
based on expert evaluations of the potential for the contaminant to occur in
public water systems and the potential for public health concern. The EPA is
currently working on CCL 4, which is
scheduled to be proposed early this year.
As I mentioned, choosing to make a regulatory determination
on a contaminant listed on the CCL requires
that the EPA evaluate these three criteria:
- Will
the contaminant have an adverse effect on the health of humans? This
includes determining what the adverse effect is (cancer, liver damage,
thyroid problems) and the level of exposure at which the adverse effect
occurs, known as the level of concern.
- Does
the contaminant occur in public water supplies at the level of concern,
and if so, how frequently? This information is collected from sampling
data, including research data from the United States Geologic Survey;
United States Dept of Agriculture pesticide data program; chemical
production data; and from the data collected by the Unregulated
Contaminant Monitoring Rule, or UCMR.
- Is
there a meaningful opportunity for health risk reduction? A number of
factors are taken into consideration for this, including the number of
people who are at risk of exposure from drinking water; whether the
contaminant has particular effects on sensitive populations such as
children, the elderly, or those with compromised immune systems; and the
relative exposure from water versus other sources such as food.
After the EPA makes a regulatory decision on a contaminant,
the next step is to set a
Maximum Contaminant Level Goal (MCLG). The EPA
reviews numerous health effects studies before setting the MCLG, the maximum
level of a contaminant in drinking water at which no known or anticipated
adverse effect on the health of persons would occur, and which allows an
adequate margin of safety. MCLGs are non-enforceable public health goals. Since
MCLGs consider only public health and not the limits of detection and treatment
technology, sometimes they are set at a level which water systems cannot meet.
When determining an MCLG, EPA considers the risk to sensitive subpopulations
(infants, children, the elderly, and those with compromised immune systems) of
experiencing a variety of adverse health effects. For microbial contaminants that may present
public health risk, the MCLG is set at zero because ingesting one protozoa,
virus, or bacterium may cause adverse health effects. If there is evidence that a chemical is a
carcinogen, a substance which may cause cancer, and there is no dose below
which the chemical is considered safe, the MCLG is set at zero. If a chemical
is carcinogenic and a safe dose can be determined, the MCLG is set at a level
above zero that is safe. For chemicals that
can cause adverse non-cancer health effects, the MCLG is based on the reference
dose. A reference dose (RfD) is an estimate of the amount of a chemical that a
person can be exposed to on a daily basis that is not anticipated to cause
adverse health effects over a person's lifetime. In RfD calculations, sensitive
subgroups are included, and uncertainty may span a factor of 10 or more. The
RFD is multiplied by body weight and divided by daily water consumption to
provide a Drinking Water Equivalent Level (DWEL). The DWEL is multiplied by the
relative source contribution which is the percentage of the RfD remaining after
considering other exposure routes (e.g. food, inhalation, etc.) to determine
the MCLG.
Once the MCLG is determined, EPA sets an enforceable
standard. In most cases, the standard is a Maximum Contaminant Level (MCL),
the maximum permissible level of a contaminant in water which is delivered to
any user of a public water system. When there is no reliable method that is
economically and technically feasible to measure a contaminant at particularly
low concentrations, a Treatment Technique (TT) is set rather than an MCL.
A treatment technique is an enforceable procedure or level of technological performance,
which public water systems must follow to ensure control of a contaminant. The MCL
is set as close to the MCLG as feasible. EPA must determine the feasible MCL
or TT which the Safe Drinking Water Act defines as the level that may be
achieved with the use of the best available technology, treatment techniques,
and other means which EPA finds are available (after examination for efficiency
under field conditions, not solely under laboratory conditions) are available,
taking cost into consideration. EPA must also prepare a Health Risk Reduction
and Cost Analysis (HRRCA) in support of any new MCL
that analyzes all benefits that are likely to occur as the result of compliance
with the proposed standard. They must also analyze any increased costs that
will result from the proposed drinking water standard. EPA must also consider
costs and benefits associated with a range of MCL
values; health effects to the general population and sensitive sub-populations;
and any increased health risk to the general population that may occur as a
result of the new MCL. Primary drinking
water standards go into effect three years after they are finalized. If capital
improvements are required, EPA's Administrator or a state may allow this period
to be extended up to two additional years.
Wow – that’s a lot to go through to implement a new
regulation. No wonder it can take so
long for this process to work itself out.
Next time we’ll look at the process of setting regulations specific to
the State of California.