Nina I. McClelland David A. Gregnrka Betsy D. Carltnn Natioml Sanitation Foundation Ann Arbor, MI 48106 Additives to drinking water come in many forms. While improving the overall quality of water, some water 14 Envimn. Sci. Techno!.. Vol. 23,No. 1. 1989
treatment chemicals may impart heavy metals, radionuclides, or organic contaminants to the water. Nearly all chemicals used in the water industry have trace levels of contaminants associated with them, and depending on the source and production method, contamination of the water supply may or may not be threatened. Another source of additives to water supplies is the materials used in distribution and plumbing systems, such as coatings, pipes, gaskets, and valves. Significant levels of inorganic and organic chemical contaminants may leach or be extracted from metal and synthetic materials used in drinking-water systems.
Microbiological regrowth in distribution and plumbing systems is another documented health problem. Contributors to the regrowth problem are certain materials used in these systems. In one case reported in the literature, a hospital with a Legionella contamination problem was unable to disinfect its water system. Superchlorination and the circulation of hot water through its plumbing system did not eliminate the regrowth problem. The source of the problem was eventually traced to natural rubber fittings used in the hospital's water distribution system. All were replaced with a less biologically active material, and the regrowth problem was solved. Today the National Sanitation Foundation (NSF) has many current and prospective programs that are focused on drinking-water quality. They include a series of standards for devices that treat drinking water at the point of use and the point of entry;
M ) 1 3 9 3 8 W W ~ 2 3 0 0 1 4 1 . 5 0 / 0 0 1988 American Chemical Society
standards for plastics piping systems and for flexible membrane liners used in reservoirs and aqueducts; and certification of bottled water, packaged ice, and drinking-water treatment laboratories. Under its Safe Drinking Water Act authority, EPA has been evaluating additives products. States, water utilities, and others have relied on EPA’s opinions to make decisions about accepting or rejecting additives products for use in public water systems. Resource constraints and other demands have limited EPA’s activities to issuing new advisory opinions for products that are virtually identical to products previously reviewed. Recognizing the shortcomings of the current program; the l i i l i i d of no increases in future program funding; and the needs of states, public water systems, and manufacturers for the evaluation of additives products, EPA requested proposals for the establishment of a voluntary, third-party, private-sector additives program. EPA required that voluntary consensus standards be developed, and that the successful bidder offer a program of third-party certification based on the StandaIdS. As a result of the proposal, NSF entered into a cooperative agreement with EPA to develop a voluntary, third-party, private-sector program for evaluating drinking-water additives. NSF has led this effort through a unique consortium approach, which includes the American Water Works Association Research Foundation (AWWARF), the Conference of State Health and Environmental Managers (COSHEM), and the Association of State Drinking Water Administrators (ASDWA). In September 1987, the American Water Works Association (AWWA) joined the team. EPA intends that this new third-party program replace EPA’s existing additives advisory program, as announced by the agency in the Federal Register on July 7 , 1988.
store, and distribute drinking water. They are not performMce standards, and do not reference performance requirements.
fers input from all concerned parties, balanced participation, a means for adjudicating negatives, and an appeals process.
Standards development Various working and advisory groups
Scope of standards
and committees were established to develop the new standards. These groups-which included representatives from industry, regulatory agencies, water utilities, other product users and specifiers, and public interest groups-played a major role in defining and developing the additives program. A steering committee was responsible for overall policy setting, grant administration, the formal program work plan, and program coordination. It did not, however, become involved in standards writing or balloting. This group was chaired by the principal investigator (NSF), and includes representatives of EPA, AWWARF, ASDWA, COSHEM, and AWWA. Standards and criteria were developed through NSF’s established voluntary consensus standards development process. Task groups drafted requirements for the product categories, in-
The additives program has produced two standards. One addresses direct additives and includes all chemicals used in drinking-water treatment and in water well drilling. The second deals with indirect additives, including all materials in contact with drinking water during its treatment, storage, transmission, and distribution. Specific sections of each standard deal with variabilities of each product type, including degree or extent of exposure to drinking water. The Health EffectsTask Group had primary responsibility for maintaining consistent requirements for all products, based on sound, scientific principles of public health.
Toxicology requirements The toxicological requirements under Standards 60 and 61 are predicated on protecting the public health through careful consideration of both the additive product or material and the con-
“Thenew NSF additives standards relate to real and potential health effects.”
cluding protective materials; pipes and related products; joining and sealing materials; mechanical devices; process media; coagulation and flocculation chemicals; disinfection and oxidation chemicals, chemicals for corrosion and scale control and softening, precipitation, sequestering, and pH adjustment; and miscellaneous treatment applications. A Health Effects Task Group addressed toxicological and risk considerExisting standards ations. A Peer Review Group of exThere are several existing NSF per- perts in toxicology and analytical formance standards for products used chemistry was established to bring adin contact with drinking water, and nu- ditional expertise and an added level of merous product or materials standards review to the effort. Requirements are available from the AWWA, the drafted by the Health Effects Task American Society of Sanitary Engi- Group were reviewed and approved by neering (ASSE), the American Society the Peer Review Group. for Testing and Materials (ASTM), and The NSF standards develomnent others. A W A and ASSE performance methodology is consistent with Ameristandards complement current and pro- can National Standards Institute (ANSI) posed NSF health effects standards. guidelines, and NSF is “an aCciedi& Other NSF standards, such as Standard ANSI standards organization.” This is 14 (plastic piping components), refer- one of two available classes of ANSI ence ASTM and other standards for accreditation. NSF’s standards are acperformance. By Joint Committee deci- cepted by ANSI without additional balsion, the new NSF additives standards lot. In conformance with the Office of relate to real and potential health @em Management and Budget A-119 guideassociated with products used to treat, lines and ANSI requirements, NSF of-
taminants or impurities the product or material could contribute. The principle of commensurate effort is central to the toxicology evaluation approach. This principle states that the amount of data required to determine the safety of an additive should be proportional to the additive’s potential for causing adverse health effects. The basic precepts of toxicology suggest that the potential for any substance to cause an adverse health effect is related to the level of exposure or dose. Therefore, more data are required for highexposure, highrisk additives than for low-exposure, low-risk additives. The Drinking Water Additives Program standards are consistent with federally regulated drinking-water standards. For regulated contaminants, the maximum allowable level (MAL) described in Standards 60 and 61 is based on the EPA reeulated maximum contaminant level &ICL), with the MAL equal to 10% of the MCL. The 10% level was chosen to account for multiple sources of one contaminant. This is consistent with the approach taken in the National Academy of Sciences’ Water Chemicals Codex. The U S . Food and Drug Administration (FDA) emEnvimn. Sci. Technol., Vol. 23, NO.1, 1989 15
ploys similar estimations of murce contributions from various types of products in its regulation of fond additives. For unregulated contaminants, a maximum drinking-water level (MDWL) is calculated, based on toxicology data and appropriate risk assessment
models, and adjusted for the exposure concentration of the contaminant a! !he tap. The toxicology evaluation procedures in Standards 60 and 61 are similar to those used by FDA in its evaluation of fond additives. Both systems use
te decay curve: Drinking-WaterAddifies Program test for initial concentration of contaminants
mining whether an additive is I"liied9
L
16 Enviim. Sci. Technol., MI.23, NO. 1,1988
exposure concentrations in grouping additives for evaluation. Under the Drinking Water Additives Program, the exposure concentration ranges associated with each toxicity testing category are as follows: Category Level I < IO ppb Category Level II 2 IO ppb < 50 ppb Category Level III 2 50 ppb < loo0 ppb Category Level I V z loo0 ppb Practical considerations were used in the selection of exposure concentration limits for the four testing categories. For example, most noncarcinogenic substances are regulated at concentrations between 10 and loo0 ppb. It is therefore important that the potential for target-organ toxicities (toxic effects on specific organs in the body) of any substances present in tap water within this range be characterized prior to permitting this substance in a drinking-water system. Similarly, the mutagenic PL+ tential of an additive (as predictor of carcinogenic potential) needs to be determined at or below the IO ppb range at which most carcinogenic substances are regulated. The toxicity testing requirements in each exposure category build on the requirements of the exposure level below it. In the first category (
