NSF/ANSI STANDARD 61 NSF/ANSI STANDARD 61 FRAMEWORK FOR FRAMEWORK FOR

RISK ASSESSMENTSRISK ASSESSMENTS

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Cost of Risk Assessment Cost of Risk Assessment DevelopmentDevelopment

• Company with products to Certify– Enabling certification of their product

• Certifier– Has identified a risk assessment need to better

serve their clients

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Risk Assessment DevelopersRisk Assessment Developers

• Certifiers with Toxicology Staff

• Company with products to Certify– Primarily larger chemical manufacturers with

Toxicology Staff

• Risk Assessment Contractor

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External Peer ReviewExternal Peer Review

• Health Advisory Board

• Facilitated by NSF International

• Maintain a panel of Toxicologists who are experts in their field

• Review about 30 documents per year

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Incorporation into StandardIncorporation into Standard

• Joint Committee maintains the Standard

• New criteria that pass the Health Advisory Board are submitted to the Joint Committee for adoption into the Standard

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FrameworkFramework

• Certified Companies provide the funds to support Risk Assessment development

• Directly through individual risk assessments

• Indirectly through service with the Certifiers

• Certifiers facilitate the external peerreview

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NSF RISK ASSESSMENT NSF RISK ASSESSMENT PROCEDURES FOR THE PROCEDURES FOR THE

EVALUATION OF EVALUATION OF CHEMICAL SUBSTANCES CHEMICAL SUBSTANCES

IN DRINKING WATERIN DRINKING WATER

BASED ON U.S. BASED ON U.S. ENVIRONMENTAL ENVIRONMENTAL

PROTECTION AGENCY PROTECTION AGENCY GUIDELINESGUIDELINES

Incorporated Into NSF/ANSI Standards 60

and 61, ANNEX A

APPROACHESAPPROACHES

• Use a published and peer reviewed assessment

• Perform a qualitative or a quantitative risk assessment

• For a quantitative risk assessment, use non-cancer or cancer procedures

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NSF RISK ASSESSMENT NSF RISK ASSESSMENT VALUES (NSF/ANSI 61)VALUES (NSF/ANSI 61)

• Total Allowable Concentration (TAC)

• Single Product Allowable Concentration (SPAC)

• Short Term Exposure Level (STEL)

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USE OF A PUBLISHED AND USE OF A PUBLISHED AND PEER REVIEWED PEER REVIEWED

ASSESSMENTASSESSMENT• U.S. EPA MCLs and Health Canada MACs

accepted, other assessments evaluated • Has to be publicly available• Has to have undergone external peer review• Has to reflect the oral route of exposure• Has to follow U.S. EPA or International

guidelines

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MINIMUM STUDY QUALITY MINIMUM STUDY QUALITY FOR RISK ASSESSMENTSFOR RISK ASSESSMENTS

• Studies evaluated for use in risk assessments should be performed in accordance with OECD or U.S. EPA guidelines.

• Studies should be evaluated for compliance with Good Laboratory Practice guidelines.

• Some judgment is allowed regarding hazard to human health in evaluating older, non-compliant, studies.

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REVIEW REQUIREMENTS REVIEW REQUIREMENTS FOR A NEW OR UPDATED FOR A NEW OR UPDATED

RISK ASSESSMENTRISK ASSESSMENT• Although NSF/ANSI Standards 60 and 61

specify minimum requirements for a new or updated risk assessment, all available information regarding a chemical should be considered.

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QUALITATIVE RISK QUALITATIVE RISK ASSESSMENTASSESSMENT

• Done when data are not available to do a quantitative risk assessment.

• Minimum required studies are a gene mutation assay (bacterial reverse mutation) and a chromosomal aberration assay (in vitro preferred), both with and without exogenous metabolic activation.

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QUANTITATIVE RISK QUANTITATIVE RISK ASSESSMENTASSESSMENT

• Same requirements as a Qualitative study, plus a minimum of a subchronic toxicity study (90-day repeated dose) in a rodent species, preferably by the oral route.

• Includes carcinogenic or non-carcinogenic endpoints.

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QUANTITATIVE RISK QUANTITATIVE RISK ASSESSMENT KEY ASSESSMENT KEY

COMPONENTSCOMPONENTS• Chemical’s Critical Effect

• NOAEL/LOAEL/Benchmark Dose

• Uncertainty Factors

• Generate Reference Dose (RfD)

• Calculation of Water Criteria (TAC,SPAC, sometimes STEL)

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Uncertainty FactorsUncertainty Factors

• Uncertainty factor of 1, 3, or 10 are selected to cover various areas of uncertainty (e.g. interspecies & intraspecies variation, short-term to long-term extrapolation, data base deficiencies, etc.)

• These uncertainty factors are multiplied together to give the total uncertainty factor

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EXAMPLE CALCULATION:EXAMPLE CALCULATION:REFERENCE DOSE (RfD)REFERENCE DOSE (RfD)

RfD (mg/kg-day) =

NOAEL or LOAEL or BMDL (mg/kg-day)

Total Uncertainty Factor

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EXAMPLE CALCULATION: EXAMPLE CALCULATION: TAC CALCULATIONTAC CALCULATION

TAC =

[RfD x Body Weight] – [other sources]

Drinking Water Intake (L/day)

RfD is in mg/kg-day

Other sources are in mg/dayFor use by Toxicology Sub

Committee only. Please do not copy or distribute.

STEL CALCULATIONSTEL CALCULATION• Not to be used for linear carcinogens, and

used only on a case-by-case basis, as appropriate, for non-linear carcinogens with an additional uncertainty factor

• Based on 10 kg body weight and 1 L/day drinking water intake of a child, otherwise similar to TAC calculation, although a shorter-duration study may be used

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THRESHOLD OF THRESHOLD OF EVALUATIONEVALUATION

• Used when data are insufficient to do even a qualitative risk assessment (i.e. no mutagenicity and/or chromosomal aberration study is available)

• TAC is 0.003 mg/L, SPAC is 0.0003 mg/L and STEL is 0.01 mg/L

• Not used if structure activity relationships or other data suggest an adverse health effect at those levelsFor use by Toxicology Sub

Committee only. Please do not copy or distribute.

CLASS-BASED EVALUATION CLASS-BASED EVALUATION CRITERIACRITERIA

• Used when some members of a class (i.e. aliphatic ketones) have data sufficient to conduct quantitative risk assessments, but the chemical of interest does not

• Level for the class shall not exceed the lowest MCL or TAC and SPAC identified for the chemicals of known toxicity

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DIFFERENCES FROM DIFFERENCES FROM REGULATORY LEVELSREGULATORY LEVELS

• NSF levels are based on health effects only, while regulatory levels may include analytical capability to detect the chemical, technical feasibility, and other considerations

• Regulatory agencies may require data gaps to be filled, while NSF bases its levels on existing data with additional uncertainty factors to account for deficiencies

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