If you don’t comprehend the significance of water, then you’re likely not a human being living on planet Earth. Or any other living thing, for that matter. Even nanobes, the smallest cell-walled organisms (although there is debate as to whether “life” is present), require moisture to survive. For the rest of us, microorganisms like these cannot be present in our water by the time to drink it.
Due to the sheer importance of clean water, an agglomeration of standards is dedicated to drinking water systems. These standards have even reached such substantial levels of user importance that two notable standards—NSF/ANSI/CAN 61-2022 and NSF/ANSI/CAN 60-2021—even have a companion standard. This is NSF/ANSI/CAN 600, and it focuses on the “Health Effects Evaluation and Criteria for Chemicals in Drinking Water.”
Origin of NSF/ANSI/CAN 600
These two drinking water product standards have seen a medley of changes over the years. First commencing development at the request of the U.S. Environmental Protection Agency (EPA) in 1985 and first published in 1988, NSF/ANSI 61 and NSF/ANSI 60, while also being American National Standards, were designated as National Standards of Canada in 2019, hence their current designation NSF/ANSI/CAN. Their 2018 revisions saw the issuing of NSF/ANSI/CAN 600, the content of which had previously existed in the annexes of these two standards.
Specifically, Clause 3 of NSF/ANSI/CAN 600, “Toxicology review and evaluation procedures,” existed in past editions of NSF/ANSI 61 and 60 as Annex A, and 4, “Normative drinking water criteria” used to be Annex C in NSF/ANSI 60 and Annex D in NSF/ANSI 61.
You can learn more about these other standards in our posts NSF/ANSI 60-2021: Drinking Water Chemicals Health Effects and NSF/ANSI 61-2022: Drinking Water System Components – Health Effects.
NSF/ANSI/CAN 600: What’s Covered?
In providing support, NSF/ANSI/CAN 600 contains information on the toxicological review and evaluation procedures for substances imparted to drinking water through contact with drinking water system components and additives. In defining these areas, the standard establishes the human health risk, if any, to drinking water under the anticipated use conditions of these products.
Changes to NSF/ANSI/CAN 600-2023
The first edition of NSF/ANSI/CAN 600 was released in 2018, and it was revised in 2019. The current, 2023 edition, revises the 2021 version and is provided with the current editions of NSF/ANSI 61 and NSF/ANSI 60. It went through the following changes:
- Updates were made to the definitions for “acute exposure,” “benchmark dose modeling,” “the cancer slope factor,” “human equivalent dose,” “short-term exposure level,” “target substance,” “toxicodynamics,” and “weight of evidence.”
- Definitions were added for “CBEL,” “quantitative structure activity relationship,” and “structure activity relationship.”
- Updates were made to the quality assessment of study review in 3.3.1.
- Updates were made to study durations of exposure to be consistent throughout section 3, “Toxicology review and evaluation procedures.”
- Study requirements in Tables 3.1, “Qualitative risk assessment data requirements,” and 3.2, “Quantitative risk assessment data requirements,” were refined.
- The text for the benchmark dose modeling approach in Section 126.96.36.199.3 was updated.
- Updates were made to the uncertainty factor selection, including the addition of key questions to Table 3.4, “Uncertainty factors (UFs).”
- Updates were made to Table 3.5, “Unit Riskage values,” regarding lifestage adjustment based on the revised Exposure Factors Handbook for drinking water ingestion.
- Table 3.6, “Peer reviewed risk values,” and additional guidance associated with review of authority documents were removed.
- Section Tables were moved to within the section as opposed to the end of the document for better readability.
- Initiative to update the STEL guidance was completed and is reflected in the revised NSF/ANSI/CAN 600 that includes study and uncertainty factor selection guidance.
- Updates were made to Table 4.1, “Drinking water criteria.”
Changes to NSF/ANSI/CAN 600-2021
- A definition was added for reference concentration (RfC).
- The drinking water intake rates were updated in Section 3, “Toxicology review and evaluation procedures.”
- Pass/fail values for contaminants were updated in Table 4.1, “Drinking water criteria.”
- Footnote 7 was revised to reference new optional lower lead Q value under NSF/ANSI/CAN 61.
NSF/ANSI/CAN 61-2022: Drinking Water System Components – Health Effects and NSF/ANSI/CAN 60-2021: Drinking Water Treatment Chemicals – Health Effects come with a complementary copy of NSF/ANSI/CAN 600 from the ANSI Webstore.