310 CMR, § 40.0993 - Method 3 Human Health Risk Characterization

Under Method 3, the risk of harm to human health shall be characterized for all current and reasonably foreseeable Site Activities and Uses identified in 310 CMR 40.0923, as follows:

(1) The site, receptor and exposure information described in 310 CMR 40.0901 through 310 CMR 40.0920 shall be identified and documented.

(2) The groundwater and soil categories applicable to the disposal site shall be identified and documented, as described in 310 CMR 40.0930. The groundwater and soil categories shall be considered as general indicators of exposure potential in a Method 3 evaluation.

(3) All applicable or suitably analogous health standards shall be identified in the documentation of the Method 3 Risk Characterization. The MCP Method 1 Groundwater and Soil Standards listed in 310 CMR 40.0970 are not considered applicable or suitably analogous, as those standards represent an alternative approach to Method 3. The list of potentially applicable or suitably analogous standards includes, but is not limited to:

(a) Massachusetts Drinking Water Quality Standards promulgated in 310 CMR 22.00: Drinking Water, including the requirements described at 310 CMR 22.03(8), which are considered applicable to all category GW-1 groundwater;

(b) Massachusetts Air Quality Standards promulgated in 310 CMR 6.00: Ambient Air Quality Standards for the Commonwealth of Massachusetts; and

(c) Massachusetts Surface Water Quality Standards promulgated in 314 CMR 4.00: Massachusetts Surface Water Quality Standards.

(4) The frequency, duration and intensity of exposure to each oil and/or hazardous material at the disposal site for each receptor at each Exposure Point shall be determined and documented, considering the current and reasonably foreseeable Site Activities and U ses identified for the disposal site. The magnitude of each receptor's total exposure to the oil and/or hazardous material at the disposal site is calculated in a manner which provides a conservative estimate of the potential exposures. Assessments conducted using a probabilistic analysis shall identify the 95^th percentile estimate of each receptor's potential exposure.

(5) For each identified Human Receptor, cumulative cancer risks and cumulative non-cancer risks shall be calculated. Chemical-specific toxicity information used to estimate the cancer and non-cancer risks shall be identified and documented, and the selection of this information shall take into account standards and guidance published by the Department. Primary consideration shall be given to information developed by the Massachusetts Department of Environmental Protection for the purpose of conducting such risk assessments. Examples of such toxicity information include:

(a) Reference Doses and Reference Concentrations; and

(b) Carcinogenic Slope Factors and Unit Risks values.

(6) When identifying toxicity values for use in a Method 3 Risk Characterization, toxicity values developed by MassDEP shall be used.

(a) For perchlorate, a chronic and subchronic reference dose of 7E-5 mg/(kg-day).

(b) For methyl tert-butyl ether, a chronic RfD of 1E-1 mg/(kg-day).

(c) For methyl tert-butyl ether, a subchronic RfD of 1E0 mg/(kg-day).

(d) For tetrachloroethylene, an oral cancer slope factor of 2E-2 per mg/(kg-day).

(e) For tetrachloroethylene, an inhalation unit risk of 3E-6 per ug/cubic meter.

(f) For the sum of the following per- and polyfluoroalkyl substances (PFAS), a chronic and subchronic reference dose of 5E-6 mg/kg/day:

1. Perfluorodecanoic acid (PFDA);

2. Perfluoroheptanoic acid (PFHpA);

3. Perfluorohexanesulfonic acid (PFHxS);

4. Perfluorononanoic acid (PFNA);

5. Perfluorooctanesulfonic acid (PFOS); and

6. Perfluorooctanoic acid (PFOA).

(7) If an applicable toxicity value is not listed at 310 CMR 40.0993(6), technical justification for the value selected must be provided. Preferential consideration shall be given to sources of toxicity values in accordance with the following hierarchy:

(a) Toxicity values adopted and otherwise published by MassDEP;

(b) Toxicity values listed in EPA's Integrated Risk Information System (IRIS) database; and

(c) Other EPA and non-EPA sources including, but not limited to, EPA Provisional Peer Reviewed Toxicity Values (PPRTVs); Minimum Risk Levels (MRLs) published by U.S. Agency for Toxic Substances and Disease Registry (ATSDR); and values published by California Environmental Protection Agency. In selecting a source for a toxicity value, there should be a preference for toxicity assessments that are informed by current scientific information and account for the most sensitive endpoints.

(8) For receptors who may be exposed to mixtures of oil and/or hazardous material, or through multiple Exposure Pathways at the disposal site, the cumulative risk shall reflect those multiple exposures. Risk estimates are presumed to be additive unless an alternative mechanism is demonstrated to be appropriate.

(9) Risk calculations performed using a probabilistic analysis shall identify the cumulative cancer and non-cancer risks associated with the 95^th percentile estimate of exposure.

(10) The Cumulative Receptor Cancer Risks shall be compared to a Cumulative Cancer Risk Limit which is an Excess Lifetime Cancer Risk equal to one-in-one hundred thousand. Cumulative Receptor Non-cancer Risks shall be compared to a Cumulative Non-cancer Risk Limit which is a Hazard Index equal to one. Estimated Exposure Point Concentrations shall be compared to any applicable or suitably analogous standards.

(11) A condition of no significant risk of harm to human health exists or has been achieved if:

(a) no Exposure Point Concentration of oil and/or hazardous material is greater than an applicable or suitably analogous public health standard;

(b) no Cumulative Receptor Cancer Risk calculated is greater than the Cumulative Cancer Risk Limit; and

(c) no Cumulative Receptor Non-cancer Risk is greater than the Cumulative Receptor Non-cancer Risk Limit.

(12) The documentation of the Method 3 human health Risk Characterization shall clearly state whether or not a condition of no significant risk of harm to human health exists or has been achieved, based upon the criteria described in 310 CMR 40.0993(11).

(13) All mathematical equations used to calculate cumulative receptor cancer and non-cancer risks shall be clearly presented and documented.

Notes

310 CMR, § 40.0993

Amended by Mass Register Issue 1407, eff. 12/27/2019. Amended by Mass Register Issue 1503, eff. 3/1/2024. Amended by Mass Register Issue S1516, eff. 3/1/2024.