Sep 04, 2020

Understanding the Toxicology Requirements in NSF/ANSI Water Standards

Do not let the toxicology requirements in drinking water standards sink your product

water certification requirements

Manufacturers may know that NSF/ANSI drinking water standards evaluate health effects from a product, but many are not aware of the toxicological work that goes into establishing a test program and confirming compliance. Having insight into these requirements not only helps explain why detailed product information is needed at the onset of a certification project but also clarifies why a project may take longer than expected when a pass/fail level does not exist for a compound extracting from the product. Further, having a basic understanding of how toxicology plays a part in the NSF/ANSI drinking water standards can help manufacturers design products that are more likely to comply.  

Some of the standards that establish toxicology requirements by evaluating what leaches out of products into drinking water include:

  • NSF/ANSI/CAN 61: Drinking Water System Components – Health Effects establishes health effects requirements for products that come into contact with drinking water.
  • NSF/ANSI/CAN 60: Drinking Water Treatment Chemicals – Health Effects establishes health effects requirements for direct and indirect water treatment chemicals.
  • NSF/ANSI 42, 44, 53, 55 58, 401 establish not only health effects requirements but also performance, structural, and literature requirements for drinking water treatment units.

When certifying a product to these standards, a manufacturer should know the answer to key questions up front:

  • When and what information is required on my product?
  • How is a test battery established?
  • Where do the pass/fail levels for product extractants come from?
  • What happens if a clearance level does not already exist?

Yet, many manufacturers are surprised by how much information is required at the start, what happens when a clearance does not exist, and the reasons that lead to increased certification costs.

Information Gathering During Preevaluation Toxicology

Preevaluation toxicology begins by gathering information which will help determine the test battery to use for your product. This  includes:

  • Product end use;
  • Temperature rating;
  • Surface area or size range of product;
  • Volume of water the product is anticipated to hold/come into contact with; and 
  • Wetted parts list or formulation information.

Depending on the type of product, a wetted parts list, full formulation, or both may be required. Additional information requirements are determined based on the end use of the products. After receiving information from the client, if the product deals with water treatment chemicals, barrier materials, joining and sealing, or process media, then formulation information is needed. For products such as pipes and related products, mechanical plumbing devices, and water treatment units, a wetted parts list is required. From there, if all materials are not coatings or process media then a NSF/ANSI 61 test battery can be determined without additional information. If some materials are process media or coatings, then a formulation will be required.

If formulation information is required, the following information will need to be provided:

  • Full formulation disclosure equal to 100% of all components combined;
  • Chemical Abstract Service (CAS) registry numbers;
  • Compound name; and
  • Supplier information (including alternate suppliers for the same component).

If your product contains alternate suppliers, you need to disclose them. However, alternate suppliers of the same material or ingredient may not require separate testing evaluations. If you have alternate components made of slightly different materials, for example, alternating between rubber gaskets made of nitrile butadiene rubber (NBR) and styrene-butadiene rubber (SBR), both of the components will need testing evaluations.

Depending on the product type, end use and the components within the wetted parts list, the information can be reviewed to determine if full formulation review and information gathering can be waived. For example, some materials exempt from formulation information requirements include:

  • NSF/ANSI/CAN 61 — The specific material is listed in Table 3.1 (ex. Polyethylene, ductile iron, EPDM) and also meets one of the following: Diluted surface area application ≤ 0.001 sq in/L; used in high flow products exclusively for public water treatment facilities; and used in a mechanical device or mechanical plumbing device but is not a coating or process media.
  • NSF/ANSI/CAN 61 — The generic material (e.g., plastics, elastomers and metallic materials) is listed in Table 3.2 and used in a mechanical device or mechanical plumbing device but is not a coating or process media. Table 3.2 has an optional more costly, extensive test battery but allows for testing to take place with limited information.
  • Water treatment units — Materials compliant with U.S. Code of Federal Regulations (CFR), Title 21.

Designing your product with materials exempt from formulation requirements or components/ingredients already certified can often help speed up the certification process.

Formulation Review

With the preevaluation toxicology information obtained, a formulation review is done. Formulation review is required for any material that is not exempt from the full formulation information. Certain chemicals are excluded if recognized in a list in the NSF/ANSI/CAN 60 standard. As part of their review, the toxicologist evaluates each ingredient from each formulation taking into consideration the following:

  • Known or suspected toxicity of the substance or its byproduct(s);
  • High water solubility of the substance;
  • Monomer(s) and polymeric ingredients;
  • Solvents and cosolvents used in the polymerization process or those used in material formulation;
  • Antioxidants, antimicrobials, curing agents, initiators, peroxides, pigments, plasticizers, process aids, stabilizers, and terminators and their impurities, degradation and hydrolysis products;
  • High probability of extraction of a substance or its byproduct(s) at toxicologically significant concentrations; and 
  • Extraction or migration of information for the substance provided by the manufacturer or presented in public literature.

The toxicologist then combines the formulation-dependent analytes from their review with the material-specific analytes identified in the standard to create an analytical summary of all test requirements for that material. For example, if the product is covered under NSF/ANSI/CAN 60, the final test battery will be determined by the tables outlined in the standard as well as any additional analytes from the analytical summary. If there are no additional analytics or an analytical summary needed, then the test battery is fully dependent on the tables of NSF/ANSI/CAN 60.  

Post-Evaluation Toxicology

Once the test battery is identified, the product is evaluated according to the requirements in the relevant NSF/ANSI standard. The resulting test water is analyzed for the analytes of interest identified according to the process above and data is received showing which compounds were extracted from the product. Since there are some limitations to testing products in the laboratory, the concentrations of the extractants from the test data do not always match the concentrations you would typically see in the field based on size or field use. Therefore, the resulting data may be adjusted (normalized) to match the concentrations you would see for the typical end use of the product. The normalized concentrations are then compared to the pass/fail criteria that is defined in NSF/ANSI/CAN 600. NSF/ANSI/CAN 600, Health Effects Evaluation and Criteria for Chemicals in Drinking Water is the standard that defines the toxicological review process and evaluation procedures and contains all of the currently acceptable pass/fail concentrations of chemicals that are found in the samples being evaluated.

If a compound is present in the evaluation water, it needs to be compared to a pass/fail criteria (clearances) to determine its conformance. Pass/fail criteria clearances can be categorized into three phases:

  • Existing clearances are found in NSF/ANSI/CAN 600;
  • Clearances in progress that have been written but not published into NSF/ANSI/CAN 600 yet, e.g., currently going through Joint Peer Review Steering Committee (JPRSC) or the Health Advisory Board (HAB) review or pending publication; and
  • New clearances where determination if a new clearance is available depends on the data available for compound or surrogate, or similar compounds.

From Where Does a Contaminant’s Pass/Fail Criteria Originate?

A risk assessment establishes a pass/fail criteria for a contaminant and can vary in effort depending on the information needed and the level of clearance needed. Risk assessments can be qualitative, quantitative, threshold evaluations or class-based clearances.

  • Qualitative risk assessments require gene mutation assay and chromosomal assays.
  • Quantitative risk assessments require the same as the qualitative as well as a subchronic study, chronic study, reproduction assay or developmental assay.
  • Threshold clearances are used when the data does not meet the requirements of the quantitative or qualitative approach.
  • Class-based approaches are used to address data gaps for chemicals when structurally similarly chemicals have data and they use a read-across approach to predict toxicity of the target chemical.

Depending on the type of risk assessment performed for the clearance, different levels of peer review from external bodies may be required. Risk assessments performed to the requirements for NSF/ANSI/CAN 600 need to undergo external peer review by the Health Advisory Board unless: 

  • Substances evaluated using the Threshold of Evaluation;
  • Substances evaluated to a Total Allowable Concentration (TAC) of 10 µg/L using the qualitative approach based on chemical-specific data that are clearly negative and concluded to be nongenotoxic; and
  • Nonregulatory criteria that have already undergone peer review.

If the clearances meet the above criteria, they can be reviewed by the Joint Peer Review Steering Committee. The Joint Peer Review Steering Committee is a committee of ANSI-accredited product certification bodies combining efforts for risk assessments to be accepted or presented to the Health Advisory Board for the inclusion to NSF/ANSI/CAN 600. 

However, if a risk assessment does not meet those above criteria, it will then need to undergo peer review by the Health Advisory Board. The Health Advisory Board is a committee of toxicologists from industry, academia and government bodies that review risk assessments. When risk assessments are presented to the Health Advisory Board there are several potential outcomes: 

  • Accepted as written and presented; 
  • Tentatively accepted with minor edits required for later additional review; or
  • Rejected as presented (may resubmit if major edits are made).

If any edits are to be made or the risk assessment is to be returned to the Health Advisory Board for additional review, additional time and monetary costs may accrue until the risk assessment is either accepted or no longer pursued. For compounds not previously identified, a toxicologist will determine the viability of a risk assessment and reports on the findings. 

Due to the effort of this process, it is easy to see how a product extracting just one compound without a clearance can add time and money to a project. Designing a product using components or ingredients that already comply with the NSF/ANSI standards can help avoid some of these issues. 

Understanding the toxicology requirements early in the product certification process can greatly speed your time to market. Toxicology dictates what information is required up-front to determine a test battery. It is necessary for generating new clearances and determining if contaminants that show up during extraction testing meet requirements. An extensive process exists to obtain a new clearance level that can be time- and cost-intensive. Working with an experienced leader in testing and certification who has a full and deep understanding of the process is critical to your success. 

About the author

Ashli Henderson is project chemist for UL Water & Plumbing Systems. Henderson can be reached at [email protected].

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