United States
Environmental Protection Office of Water EPA 811-F-94-008
^ cn- Agency 4603 November 1994
FACT SHEET - SULFATE
HIGHLIGHTS OF THE PROPOSED RULE
This proposed rule is an innovative approach to regulating a naturally-occurring
drinking water contaminant.
Sulfate, a naturally-occurring anion, is one of the original 83 contaminants whose
regulation was mandated by the Safe Drinking Water Act. People who are not
accustomed to high levels of sulfate in their drinking water may experience diarrhea
when first exposed to it; however, they will generally acclimate to the sulfate in
approximately two to three weeks, with no further adverse effect. EPA is
proposing an innovative alternative to central treatment which targets those
subpopulations likely to be at risk from high sulfate levels in drinking water:
newborn infants, travelers, and new residents.
Most of the approximately 2,000 systems expected to exceed the sulfate MCL
serve populations of 3,300 people or less. The rule will affect all systems, that is,
community systems, non transient, non-community systems, and transient, non-
community systems.
The rule proposes a unique means of compliance intended to provide relief and
flexibility to small systems. A combination of public education/notification and the
provision of alternative water in the form of bottled water which has been
monitored or certified to be in compliance with all EPA MCLs, or water treated by a
filtering device, is proposed as an alternative to central treatment.
The State would have the authority to allow PWSs to achieve compliance with the
sulfate MCL either by using conventional central treatment or by providing
Alternative Water/Public Notification. Community Water Systems (CWSs) would
be responsible for providing Alternative Water (probably bottled water) on request
to any household which has an infant or travelers (guests), and to any household
with new residents who have moved to the community from outside the service
area. For CWSs, there are four components to the proposed public education and
public notification requirement: notices in bills, pamphlets, signs and notices to the
media.
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Transient systems, which comprise most of the affected systems (1,200 of 1,950),
and non-transient, non-community systems would be required to make Alternative
Water available for travelers at establishments in the service area. Where the
target population is affected on a relatively continual basis, PWSs may find it more
cost-effective to provide POU or POE devices. Where the system rarely serves
members of the target population, it might choose to have a supply of bottled
water on hand. Non-transient, non-community water systems, such as schools,
factories and hospitals, might choose to install POEs in their cafeterias. PWSs
would be responsible for maintaining POU/POE devices to ensure their continuing
effectiveness. Public notification for transient systems and non-transient, non-
community systems would consist of permanent signs, made of durable material, in
places such as rest areas, campgrounds, gas stations and public areas. The signs
would state the nearest location of drinking water for individuals not acclimated to
high sulfate levels. If the location has a POE device, posting would not be
necessary, since all taps would provide water that complies with the MCL. In the
case of campgrounds, sources such as handpumps or trailer hook-ups would be
posted with signs, and bottled water could be available at the entrance gate or
registration area.
There are no reports of adverse health effects from chronic exposure to sulfate in
drinking water. Sulfate is a normal component of human body fluids, and is found
naturally in soil and in combination with several minerals in the environment. The
laxative effect of ingesting high levels of some sulfates is well known.
The total target population, consisting of newborn infants, new residents and
travelers who would be exposed to sulfate levels in excess of 500 mg/L, is
estimated to be 1.2 million people. Most of these people are tourists and business
travelers, with 27,000 infants included in the total.
There are insufficient data to calculate a precise and reliable quantification of the
exact dose which will cause diarrhea in a given percentage of the susceptible
population. As the mechanism of sulfate action is known, there is apparently little
interest in the medical community in additional research on the subject.
Acclimation to sulfate is assumed due to the fact that people living in regions with
high-sulfate drinking water seem to have no adverse effect, whereas newcomers
drinking that region's water will initially experience the laxative effect.
There are three documented case histories of infants, 5 to 12 months old, who
were given formulas prepared with water containing 630 to 1,150 mg/L of sulfate
(Chien, et al., 1968). These infants developed diarrhea shortly after they ingested
the formula, but the effect subsided after use of the high sulfate water was
discontinued. Cole (1992) evaluated this study and concluded that neither the
potential effects of osmolarity, specifically hyperosmolarity, nor viral gastroenteritis
had been considered as possible causes of the observed diarrhea. Thus, Cole
suggested and the Agency agrees that the Chien study provides qualitative
evidence of the effects of sulfate but should not be used quantitatively in a sulfate
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risk assessment. In another study, Peterson (1951) compiled the results of
questionnaires sent to North Dakota residents and concluded that "waters with
600 to 750 ppm sulfates should be looked upon with suspicion as they may or
may not be laxative. Over 750 ppm sulfates is generally a laxative water and
below 600 ppm sulfates should be considered safe." Moore (1952) replotted the
Peterson data and found that as sulfate concentrations increased from 500 to 1000
mg/L, the number of adults reporting laxative effects also increased. At
concentrations of sulfate above 1,000 mg/L, the majority of respondents noted a
laxative effect.
The Agency is using these studies to support the MCLG, although each has
limitations. The Agency is convinced that the level of 500 mg/L is sufficiently
protective of infants and adults.
The total annual cost of reducing sulfate exposure to the target population is
estimated to be $86 million. Of this total, implementation of the unique, proposed
option is estimated to cost $7 million. The Agency assumes that, despite the
availability of this unique option, approximately 25% of the affected systems
would choose either central treatment or region a lization, for a cost of $71 million.
National monitoring costs are estimated to average $0.5 million per year, and
annual State drinking water program costs to implement the rule are estimated to
be $7 million. If central treatment were the only means of compliance with the
sulfate rule, annual national cost would be $147 million.
In addition to the principal option, other options being seriously considered by the
Agency are described. Two of the other options limit the delivery of alternative
water to newborn infants as the population subgroup for whom diarrhea can be
life-threatening. The implementation of either of those two' options would cost a
total of $16 million.
For more information, contact the Safe Drinking Water Hotline, 1-800-426-4791.
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