In Harmony

April 29, 2019

Certifiers collaborate to harmonize drinking water evaluation criteria

About the author:

Kristin Licko is toxicology manager for the Gold Seal Product Certification Program for the Water Quality Assn. Licko can be reached at [email protected].

When a contaminant is found in drinking water, one of the first questions asked usually is, “How does the detected amount compare to the safe dose?” We are seeking a baseline, to know if people are at risk of experiencing negative health effects from the amount they are exposed to. 

A similar reaction occurs when a drinking water treatment product, component or chemical undergoes material safety extraction testing to an NSF/ANSI Drinking Water Additive (DWA) or Drinking Water Treatment Unit (DWTU) standard. Although there are more than 90 drinking water contaminants regulated by the U.S. EPA, there are thousands more substances involved with manufacturing products that are used to treat drinking water. 

To understand the results of material safety extraction tests, a safe exposure level must be determined for chemicals that governmental health agencies do not regulate. For the past few decades, independent third-party testing and certification programs have referenced drinking water criteria for substances in the annexes of NSF/ANSI DWA standards (NSF/ANSI 60 and 61). If evaluation criteria were not available in these standards for a substance that was detected through extraction testing, a risk assessment was conducted following the toxicology review and evaluation procedures in Annex A of the DWA standards.

Setting a Standard

Earlier this year, a new standard was released titled NSF/ANSI/CAN 600—Health Effects Evaluation and Criteria for Chemicals in Drinking Water. This companion standard for DWA and DWTU standards combines the toxicology review and evaluation procedures with drinking water criteria for thousands of substances that could be introduced into drinking water through contact with drinking water treatment products. On a basic level, material safety extraction testing identifies substances that are introduced into drinking water by determining the amount of a substance that a consumer will be exposed to based on the product’s material and chemical composition. Evaluation criteria that are established through a risk assessment developed in accordance to NSF/ANSI/CAN 600 equate to the maximum allowable level of a substance that is considered safe for a consumer to ingest per day for a lifetime without experiencing adverse health effects. The standards refer to evaluation criteria as the Total Allowable Concentration (TAC) and Single Product Allowable Concentration (SPAC), although there is the occasionally used Short Term Exposure Level (STEL) that generally relates to higher exposure levels for a shorter period. 

For substances not already evaluated by government health agencies such as the EPA and Health Canada, NSF/ANSI/CAN 600 explains how to evaluate chemicals to establish the level at which there would be none or minimal risk to human health. Before 2013, individual users of NSF/ANSI standards could interpret the guidance in Annex A differently. Different interpretations led to the development of conflicting evaluation criteria for the same substance and would result in a product passing at one certifier and failing at another. Additionally, there was not a clear mechanism of how to incorporate drinking water criteria that had been developed through the guidance of Annex A into the standards. 

Recognizing this inconsistency and opportunity to collaborate for the betterment of public health, several certifiers cooperated to form the Joint Peer Review Steering Committee (JPRSC) in 2013. The purpose of this committee is to harmonize drinking water evaluation criteria and reduce duplication efforts amongst ANSI-accredited product certification bodies with drinking water accredited scopes. CSA Group, IAPMO R&T, NSF Intl., Underwriters Laboratories and the Water Quality Assn. committed to combining and reconciling all evaluation criteria levels that had been developed to certify drinking water treatment products and chemicals. ALS/Truesdail Laboratories also recently joined the JPRSC to contribute to the harmonization initiatives.

Harmonization Efforts

Members of this committee have worked for the past six years to review, accept and ballot evaluation criteria to the NSF/ANSI Joint Committees for inclusion to NSF/ANSI drinking water standards. Risk assessments developed through guidance in NSF/ANSI/CAN 600 now are either peer reviewed by members of the JPRSC or NSF Intl.’s Health Advisory Board (HAB), which is an expert peer review panel that serves to support all certification bodies. The HAB has existed for more than 20 years and includes members from regulatory bodies, academia, industry and consulting, each having a particular toxicological expertise to offer to the risk assessment reviews. Although the standard specifies that some risk assessments do not require external peer review, any member of the JPRSC can request that a risk assessment be presented to the HAB before inclusion into the standard.

Through this harmonization effort, it was realized that the guidance for toxicology review and evaluation procedures had not been updated in more than a decade, even though new methodologies for toxicological reviews had been implemented by regulatory bodies and used by some of the authors who developed risk assessments for NSF/ANSI compliance determinations. The absence of a systematic review and updated process also contributed to the inconsistencies between safe doses that were developed for independent third-party testing and certification programs. The JPRSC took on another initiative, along with members of the HAB and other document authors, to update the guidance. The extensive updates are expected to be balloted this year for inclusion into the next version of NSF/ANSI/CAN 600. This is a single ballot that reflects multiple years of work compared to several ballots over the past six years that have incorporated new evaluation criteria into the standards. 

When the JPRSC was formed, there were 1,250 evaluation criteria levels for substances in the NSF/ANSI standards. The latest published version of the NSF/ANSI/CAN 600 included more than 1,725 evaluation criteria levels, an increase of 475 since the committee began its work to reduce duplication in risk assessment efforts and to harmonize risk assessment methods and values used to evaluate compliance of products to NSF/ANSI drinking water standards. Many of these improvements were made through the dedicated efforts of the committee and board members, and several of them also were carried out though participation in the NSF/ANSI Joint Committee process. Due to the continued efforts of these groups, the next time a contaminant is detected in drinking water and there is not a safe value developed by a government health agency to reference, NSF/ANSI/CAN 600 may be the best place to look. 

About the Author

Kristin Licko

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