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Review of Contaminant Occurrences in Drinking Water Treatment Chemicals
A Summary Report of NSF International Results (1991 to 1999)
ANSI/NSF Standard 60: Drinking Water Treatment Chemicals - Health Effects
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(PDF Version - 55 K)Table of Contents
- 1.0 Introduction
- 2.0 Methodology of Standard 60 Evaluation
- 3.0 Discussion
- 4.0 Summary information concerning chemicals which have a high occurrence of causing a failure for a product.
1.0 Introduction
This report was prepared in response to a request from Health Canada for a summary of NSF
International (NSF) testing experience on products evaluated to the health effects requirements
of ANSI/NSF Standard 60 and to relate that experience to an estimate of the total population of
these products available in North America. ANSI/NSF Standard 60 is the American National
Standard for the evaluation of drinking water treatment chemicals for potential health effects.
Provisions for product performance and safe handling are not included in the scope of the
standard because governmental agencies and other national standards-setting organizations
provide these requirements.
NSF is a not-for-profit organization chartered in the State of Michigan dedicated to research, education, and public health service. NSF serves as a neutral third-party in the development of consensus standards for industry, regulatory agencies, and users of products, equipment, and services related to public health and the environment. NSF also provides product certification services to manufacturers of products covered by its standards on a voluntary basis.
The processes and data summarized in this report provide an overview of NSF's product testing experience of drinking water additives according to ANSI/NSF Standard 60 from 1991 to 1999. A product failure or non-compliance, as defined in this report, occurs when the product fails to meet the requirements of the standard when evaluated for use up to the maximum use level (MUL) originally requested by the manufacturer. The MUL represents the level at which the product may be added to drinking water under actual use conditions. Information has not been included that summarizes actions taken by the manufacturer in response to notification of product failure, such as accepting a restricted listing, a lowering of the product MUL, altering production processes, selecting alternate ingredient suppliers, or simply withdrawing the request for certification. Products rejected at the formulation review stage (prior to testing) due to unacceptable ingredients are not included in this report. These product non-compliances are not routinely counted but are estimated to occur approximately once in every 10 to 20 submittals.
NSF currently lists over 12,525 products to ANSI/NSF Standard 60. For the purposes of this report, NSF reviewed the results of just over 1,200 submittals, which required testing during the 1991 to 1999 period. The number of products requiring laboratory testing is significantly lower than the number Listed as testing is routinely performed on only those products which represent the worst-case potential for contributing contaminants of concern. Those results are used in turn to evaluate dilutions, repackages, relabels, and other similar product applications. For the summaries provided, each product tested, at each location, each time tested is considered a single pass or fail.
2.0 Methodology of Standard 60 Evaluation
2.1 Overview and Scope
ANSI/NSF Standard 60 was developed to establish health effects requirements for chemicals and contaminants added to drinking water from drinking water treatment chemicals. This includes both chemicals that are added and intended to be present in the finished water and those that are added but not intended to be in the finished water. The Standard does not establish performance or taste and odor requirements for these products.
Contaminants produced as by-products through reaction of the treatment chemical with a constituent of the treated water are outside the scope of the Standard and, therefore, are not addressed in this report.
All references to sections of the Standard in this report are based on the 1999 edition of ANSI/NSF Standard 60 approved on May 5, 1999.
2.2 Selection of Test Analytes
Section 3 of ANSI/NSF Standard 60 lists the minimum formulation and processing information required for review to determine the appropriate analytical testing that ensures that potential contaminants to drinking water are adequately identified. Contaminants to the water may originate from ingredients, impurities of ingredients, carryover from non-dedicated systems or transport, or as unique chemical species formed during the manufacture and/or use of the product. Formulation-dependent analytes and a minimum test battery for each chemical type are listed in sections 4.1 (Coagulation and Flocculation); 5.1 (Corrosion and Scale Control); 6.1 (Disinfection and Oxidation); 7.1 (Miscellaneous Treatment Application Products); and 8.1 (Miscellaneous Water Supply Products).
2.3 Laboratory Analysis
Chemicals covered by the scope of the Standard fall into the following five categories of products and materials:
Section 4: Coagulation and Flocculation: polyelectrolytes, metal salt coagulants, clays, and activated silica
Section 5: Corrosion and Scale Control:, Softening, Sequestering, Precipitation, and pH Adjustment: calcium
carbonate, calcium hydroxide, calcium oxide, carbon dioxide dipotassium orthophosphate,
disodium orthophosphate, EDTA, hydrochloric acid, magnesium carbonate hydroxide, magnesium
hydroxide magnesium oxide, monopotassium orthophosphate, monosodium rthophosphate,
phosphoric acid, polyphosphoric acid, potassium hydroxide, potassium tetrametaphosphate,
potassium tripolyphosphate, sodium pyrophosphate, sodium bicarbonate, sodium bisulfate, sodium
calcium magnesium, sodium carbonate, sodium hydroxide, sodium polyphosphate, glassy, sodium
sesquicarbonate, sodium silicate, sodium trimetaphosphate, sodium tripolyphosphate, sodium zinc
polyphosphate, glassy, sodium zinc potassium polyphosphate, sulfuric acid, tetrapotassium
pyrophosphate, tetrasodium EDTA, tetrasodium pyrophosphate, tripotassium orthophosphate,
trisodium orthophosphate, zinc chloride, zinc orthophosphate, zinc sulfate
Section 6: Disinfection and Oxidation: ammonia, ammonium hydroxide, ammonium sulfate, calcium
hypochlorite, chlorine, iodine, potassium permanganate, sodium chlorate, sodium chlorite, sodium
hypochlorite
Section 7: Miscellaneous Treatment Applications: fluoridation, algicide, dechlorinator & antioxidant
Section 7: Miscellaneous Treatment Applications: fluoridation, algicide, dechlorinator & antioxidant
Section 8: Miscellaneous Water Supply Products: antifoamers, distribution system rehabilitation materials, scale inhibitors, well development/rehabilitation materials, bore hole sealants
ANSI/NSF Standard 60 contains twelve distinct sample preparation protocols. The specific conditions for each are listed in annex B and are determined by the section of the Standard and chemical name that applies to each product. In brief, the most common protocol used involves preparing the sample into a solution at 10 times the manufacturer's requested maximum use level and directly analyzing for the chemicals and contaminants of concern. The analyses requested are determined by the initial formulation review.
2.4 Normalization
The concentration of the contaminants detected during the laboratory analysis are adjusted, or normalized, to reflect the contaminant concentration that would be present in the finished drinking water. The normalization calculation applied to test results on chemicals prepared into solutions at 10 times the manufacturer's requested maximum use level is as follows.
[analysis solution] mg contaminant / L analyzed solution x
[lab prep solution] L analyzed solution / mg product x
[MUL] mg product / L drinking water =
[at-the-tap exposure] mg contaminant / L drinking water
To normalize the detected concentrations of contaminants from products evaluated in their neat form (not as dosed to water), the general calculation applied to the results is as follows.
[analyzed level of contaminant in product] mg contaminant
/g product x
[conversion factor] 1g / 1000mg x
[MUL] mg product / L drinking water =
[at-the-tap exposure] mg contaminant / L drinking water
Normalization for Section 8 varies with product type and usage. Please refer to Section 8.7.1
(general); 8.7.2.1 (turbid well-drilling additives); 8.7.2 (non-turbid well-drilling additives); 8.7.3
(well-drilling foamers); 8.7.4(bore hole sealants); and 8.7.5 (separation process chemicals) for
normalization discussions and calculations.
Special use instructions are requested for products when unusual exposure and normalization consideration is necessary to adequately evaluate the product. It is often the case that these products require a footnote to the Listing indicating the restricted use of the product in potable water applications.
2.5 Toxicological Evaluation of Laboratory Test Results
The normalized laboratory contaminant concentrations are compared to the maximum allowable
level (MAL) requirements established through annex A of ANSI/NSF Standard 60. If thecontaminant is either regulated by the U.S. Environmental Protection Agency (EPA) or the
subject of a Health Canada (HC) guideline, the harmonized criteria in annex F of the Standard
are used as the basis for the MAL.
When a maximum contaminant level has not been determined by either the U.S. EPA or Health
Canada, an MAL is determined through the procedures outlined in annex A. The toxicology
evaluation procedures and requirements are based on the principal of "commensurate effort".
This principal states that the amount of data needed to determine the safety of a contaminant
should relate in some manner to its potential for causing an adverse health effect. The basic
precepts of toxicology suggest that the potential for any chemical to cause an adverse health
effect is related to the level of exposure or dose. The procedures in the standard require an
increase in the supporting toxicology data as the level of human exposure increases. Annex C of
ANSI/NSF Standard 60 provides an informative rationale document for the review and
evaluation procedures in annex A of the Standard.
3.0 Discussion
For the purposes of this report, NSF certification requirements and services can be summarized into two categories; 'initial' evaluations and follow-up 'monitoring'. The requirements for initial evaluations have been described through sections 1 and 2 of this report. Monitoring requirements begin once a product is certified and typically involve annual inspections of the production locations and sample collection at a minimum of once per year. For the purposes of this report, products were identified as failures if either they did not meet requirements during their initial evaluation or if a follow-up annual monitoring sample failed to meet requirements. Two tables summarizing NSF's extraction experience are provided. A third table is provided that includes the function descriptions that correspond to the acronyms in the first two tables. Following the tables is a section summarizing toxicology and/or use information on the chemicals and contaminants that have a higher occurrence of causing a failure for a product.
Table 1 shows the compounds responsible for non-compliances from 1991-1999 and the number of occurrences for each under initial or monitoring conditions. The current pass/fail criteria or action levels have been included for those published and circulated to the Joint Committee for Drinking Water Additives for their consideration as annexes to the Standard. Action levels are dynamic numbers and subject to change as new toxicology data becomes available. The table includes three compounds whose action levels have changed over the course of the years of testing covered by this report and are identified in the table by an asterisk. A compound was included in the table if it resulted in a non-compliance based on the action level that was applicable at the time of the review.
Table 2 provides a summary of the extractants contributing to product failures delineated by section and function of the Standard. A product may have more than one function. As such, a single product failure may be entered in Table 2 under 2 functions.
For the 1991 to 1999 period under review, there were 167 parameter failures leading to the non-compliant results under ANSI/NSF Standard 60. These failures represent 136 products from 84 plant locations. Over the nine year period, 23 of the 136 products were found non-compliant due to unacceptable concentrations of more that one analyte. Eighteen of the 23 were non-compliant due to two analytes, four were non-compliant due to three, and one due to more than four analytes. Of the 136 non-compliant products, 20% were from initial toxicological evaluations, and 80% from annual toxicological evaluations.
Testing of the 1206 product submittals evaluated in this report represents only those products NSF has evaluated to ANSI/NSF Standard 60. An estimate of the percentages of drinking water treatment chemicals covered by product certification is approximately 80 percent in the United States and 50 percent in Canada.
| Contaminant | Number of Initial Occurrences |
Number of Monitoring Occurrences |
Current Action Levels |
|---|---|---|---|
| TT The typical use level for this product is based on an acrylamide polymer application of 1mg/L and an acrylamide monomer level
of 0.05% in the polymer, or equivalent (40CFR141.111) for a carryover of not more than 0.5ppb of acrylamide monomer into
the finished water. *Action level change occurred during the study period |
|||
| 1,2,3-trichloropropane | 0 | 1 | 5 ppb |
| 1,2,4-trimethyl benzene | 0 | 1 | |
| 1,3-dichloropropene, Total cis & trans |
0 | 1 | 0.2 ppb |
| 2-chloroethylvinylether | 1 | 4 | |
| 2-methylpropanamide | 1 | 0 | |
| Acrylamide | 1 | 0 | TT (see note) |
| Antimony | 0 | 1 | 0.6 ppb |
| Aromatic chlorine | 1 | 0 | |
| Benzyl chloride | 1 | 0 | 0.2 ppb |
| Bis-(2-ethylhexyl) phthalate | 0 | 3 | |
| Bromoform | 1 | 0 | See trihalomethane |
| Cadmium | 0 | 5 | 0.5 ppb |
| Carbon tetrachloride | 1 | 4 | 0.5 ppb |
| Chloroform | 0 | 2 | See trihalomethane |
| Chloromethane * | 0 | 6 | |
| Choroethane | 1 | 0 | |
| Chromium | 0 | 1 | 10 ppb |
| Confidential compound #1 * | 4 | 38 | |
| Confidential compound #2 | 1 | 0 | |
| Confidential compound #3 | 1 | 0 | |
| Copper | 3 | 1 | 130 ppb |
| Diallyldimethyl-ammonium chloride (DADMAC) * | 2 | 5 | |
| Dibromomethane | 0 | 1 | |
| Dichloropropanols | 1 | 9 | 9 ppb (total) |
| Dimethyl(propyl) ester propanoic acid | 0 | 1 | |
| Dimethylamine * | 1 | 21 | |
| Dimethylbenzylamine | 1 | 0 | |
| Ethoxylated nonylphenol | 1 | 0 | |
| Ethylene diamine | 0 | 1 | 180 ppb |
| Glycidol | 1 | 0 | |
| Hexamine | 0 | 1 | |
| Hydroxyacetic acid | 1 | 0 | |
| Lead | 0 | 11 | 1.5 ppb |
| Mercury | 1 | 2 | 0.2 ppb |
| Methoxyphenol | 1 | 0 | |
| Methylene chloride | 0 | 5 | 0.5 ppb |
| Multicomponent phthalate | 0 | 1 | |
| Nickel | 0 | 1 | 20 ppb |
| Nitrate | 0 | 1 | 1,000 ppb |
| Nonyl phenol | 1 | 0 | |
| Phenyl methyl benzene methanamine | 0 | 1 | |
| Selenium | 1 | 0 | 5 ppb |
| Tetramethylsuccinonitrile | 1 | 0 | 0.3 ppb |
| Thallium | 1 | 1 | 0.2 ppb |
| Total haloacidic acids | 1 | 0 | |
| Trihalomethane | 0 | 1 | 8 ppb (total) |
| Unidentified nitrogen containing compounds | 0 | 1 | |
| Unidentified oxygen containing compounds | 0 | 1 | |
| Vinyl acetate | 1 | 0 | 2 ppb |
| Zinc | 1 | 0 | 300 ppb |
| Totals | 34 | 133 | |
| Function | Contaminant | Number of occurrences |
|---|---|---|
| COF | Mercury | 1 |
| PHA | Mercury | 1 |
| COR | Lead | 2 |
| CSC | Lead | 1 |
| PHA | Lead | 3 |
| COR | Cadmium | 1 |
| CSC | Cadmium | 1 |
| PHA | Cadmium | 1 |
| CSC | Mercury | 2 |
| CSC | Zinc | 1 |
| Function | Contaminant | Number of occurrences |
|---|---|---|
| DSF | Dibromomethane | 1 |
| DSF | 2-chloroethylvinyl- ether | 5 |
| DSF | 1,2,4-trimethyl benzene | 1 |
| DSF | Aromatic chlorine | 1 |
| DSF | Benzyl chloride | 1 |
| DSF | Dimethylbenzylamine | 1 |
| DSF | Bromoform | 1 |
| DSF | Carbon tetrachloride | 5 |
| DSF | Chloroform | 2 |
| DSF | Chloromethane | 5 |
| DSF | Choroethane | 1 |
| DSF | Cis-1,3-dichloropropane | 2 |
| DSF | Copper | 1 |
| DSF | Trichloroacetic acid | 1 |
| DSF | Dichloroacetic acid | 1 |
| DSF | Lead | 1 |
| DSF | Methylene chloride | 5 |
| DSF | Thallium | 1 |
| DSF | Nitrate | 1 |
| DSF | Chloromethane | 1 |
| DSF | Trihalomethane | 1 |
| DSF | Carbon tetrachloride | 1 |
| Function | Contaminant | Number of occurrences |
|---|---|---|
| DCA | Lead | 1 |
| OTH | Copper | 2 |
| OTH | Selenium | 1 |
| WDA | Lead | 1 |
| Function | Contaminant | Number of occurrences |
|---|---|---|
| OTH | Ethylene diamine | 1 |
| OTH | Hexamine | 1 |
| OTH | Unidentified oxygen containing compounds | 1 |
| OTH | Unidentified nitrogen containing compounds | 1 |
| WDA | Confidential compound #1 | 3 |
| WDA | 1,2,3-trichloropropane | 1 |
| Function | Function Description |
|---|---|
| COA | Coagulation |
| COF | Coagulation & Flocculation |
| COR | Corrosion Control |
| CSC | Corrosion & Scale Control |
| DCA | Dechlorination & Antioxidant |
| DSF | Disinfection & Oxidation |
| FLC | Flocculant |
| FLT | Filtration Aid |
| OXI | Oxidant |
| PHA | pH Adjustment |
| WDA | Well Drilling Aid |
| OTH | Other |
4.0 Summary information concerning chemicals which have a high occurrence of causing a failure for a product.
Not all parameters leading to failures have been identified with full chemical names (e.g."unidentified nitrogen containing compounds", "aromatic chlorine", "ethoxylated nonylphenol"). ANSI/NSF Standard 60 requires that the health effects of all contaminants be evaluated when determining the acceptability of a product for use in potable water applications. Low action levels for these types of contaminants are commonly set either based on the "threshold of evaluation" (T.O.E.) requirements in annex A of the standard, or are based on the toxicology of similar compounds in the same chemical class based on structural activity relationships. If appropriately conservative action levels cannot be set by these approaches, further analysis is required to attempt to specifically identify and quantify the chemical, followed by the review of all required and relevant toxicology data required by the Standard to set the action levels.
The following section is included to provide examples of common contaminants with a brief introduction to their toxicity and to identify some of the product types submitted for evaluation in which they have been found. Identification of product types as sources of the contaminants should not be construed to mean that all products of this type contain these contaminants. Please note that action levels are dynamic numbers and are subject to change as new toxicology data becomes available.
Carbon Tetrachloride is an occasional contaminant of chlorine based disinfectants used in
drinking water treatment. It has a harmonized (EPA/HC) MAL of 0.5 ppb based on the EPA's
MCL of 5 ppb. Under Proposition 65 of the California Health and Safety Code (Section
25249.5), carbon tetrachloride was listed as a chemical known to the State to cause cancer. The
California Department of Health and Safety and the International Agency for Research on
Cancer similarly concluded that the evidence for carcinogenicity of carbon tetrachloride in
animals is sufficient. Oral administration studies found carbon tetrachloride to cause hepatic
tumors (hepatomas, hepatocellular carcinomas, and preneoplastic lesions) in rats, mice, and
hamsters.
Chromium is a regulated contaminant based upon increased liver, kidney and circulatory disorders. Chromium has a harmonized MAL of 0.5 ppb based on the EPA's MCL of 5 ppb.
Confidential analyte #1 is a reaction by-product within an organic polymer used for coagulation and flocculation purposes. The action level of this analyte had been limited to 0.25 ppb (Threshold of Evaluation) due to a lack of available toxicological data. A recent confidential study has provided necessary data to allow for the action level to be increased.
Diallyldimethyl-ammonium chloride (DADMAC) monomer has resulted in non-compliance in
polyDADMAC products of Section 4, Coagulation and Flocculation. The action level for
DADMAC is based on information that is confidential to the submitter of the toxicology data.
Standard 60 restricts polyDADMAC polymer application to not exceed 25mg/L with a carryover
of not more than 50ug/L of polyDADMAC into the finished water. This Standard 60 restriction
may result in requests for re-formulation or lowered MULs at the time of the formulation review,
prior to testing.
Dichloropropanols are part of the required test battery for the polyamine polyelectrolytes
evaluated under Section 4, Coagulation and Flocculation products. 1,3-Dichloro-2-propanol and
2,3-dichloro-1-propanol are among the handful of contaminants produced via hydrolysis or ring-opening
reactions of epichlorohydrin in the presence of chlorinated water or hydrochloric acid.
To support the certification of several organic polymers under ANSI/NSF Standard 60, published
and unpublished toxicology studies were submitted to support the use of these polymers as
potable water treatment chemicals. The published literature on 1,3-dichloro-2-propanol has
identified the compound as a probable animal carcinogen in the rat, with benign and malignant
neoplasms observed in the liver, kidney and thyroid. Based on the carcinogenic potential of 1,3-
dichloro-2-propanol, NSF derived a maximum allowable level (MAL) for total
dichloropropanols of 9 ppb from a Global 86 assessment (statistical program for the estimation
of carcinogenic potency) of the carcinogenicity data for 1,3-dichloro-2-propanol.
Dimethylamine (DMA) is part of the requested test battery for the polyDADMAC, polyamine, and polyelectrolytes under Section 4, Coagulation and Flocculation. All non-compliances from dimethylamine have occurred in Section 4 products. In order to support the certification of several polymers under ANSI/NSF Standard 60, toxicological studies have been submitted to support the use of the polymers as potable water treatment chemicals. The documentation submitted for EPI/DMA polymers supports a maximum allowable level (MAL) of at least 50 ppb.
In November of 1999, NSF's Toxicology Services Department presented an MAL document to the NSF International Health Advisory Board (HAB) proposing the establishment of an updated, more scientifically based MAL of 120 ppb for DMA. However, the HAB expressed concerns with the derived drinking water action levels that were of sufficient number and seriousness to warrant further research into the matter. Specifically, the HAB asked NSF to more comprehensively address the potential formation of nitrosamines in the presence of nitrite, as well as to address the appropriateness of the use of a chronic inhalation study as the basis for MAL derivation.
In view of these concerns, NSF's toxicology department has been asked to reevaluate the DMA MAL derivation and supporting documentation prior to the HAB recommending the acceptance of an MAL other than the 50 ppb set following review of the original submissions. The revised DMA MAL document is scheduled to be presented at the next HAB meeting in the Spring of 2000. The MAL for DMA is expected to be finalized at that time.
NSF continues to use the draft MAL of 120 ppb. If the MAL for DMA is finalized during the Spring 2000 HAB meeting, NSF will use that level in the evaluation of all year 2000 product retests. If the new level is not finalized by May 1, 2000, NSF will revert back to using the MAL of 50 ppb.
Lead is a regulated contaminant capable of exposure-related increase in kidney and nervous system effects and is of particular concern in exposure to children. Lead accounts for the greatest number of regulated metal failures for products evaluated under Standard 60. From the tables that break down the non-compliance by section of the Standard, it can be seen that unacceptable lead concentrations have resulted in non-compliance in Sections 4, 5, 6, and 7 products. These failures are typically related to unintentional contamination via mineral sources and processing procedures. Lead is not allowed to be present as an intentional additive in any product based upon NSF's General Policies for product certification and is limited to an MAL of 1.5 ppb under ANSI/NSF Standard 60.
Methylene chloride has a harmonized MAL of 0.5 ppb. The action level is based on the EPA's MCL of 5 ppb. Long term exposure to methylene chloride has the potential to cause liver damage at levels above the MCL. There is some evidence that it may have the potential to induce cancer following a lifetime exposure at levels above the MCL. Methylene chloride in drinking water is primarily a disinfection by-product from chlorine use.
