Code of Massachusetts Regulations › 310 CMR - DEPARTMENT OF ENVIRONMENTAL PROTECTION › Title 310 CMR 40.0000 - Massachusetts Contingency Plan › Subpart I - RISK CHARACTERIZATION › Section 40.0983 - Derivation of Additional Method 1 Groundwater Standards for Use in Method 2

Current through Register 1525, July 5, 2024
If an MCP Method 1 Groundwater Standard has not been
				  promulgated by the Department, the RP, PRP or Other Person may develop an MCP
				  Method 2 Standard for that oil and/or hazardous material on the basis of the
				  following assumptions and procedures:
(1) A site-specific background concentration
				in groundwater shall be identified for the oil and/or hazardous
				material.
(2) GW-1 Standards shall
				be calculated as follows:
(a) Based on
				non-cancer health risk, a concentration in drinking water of the oil and/or
				hazardous material associated with a Hazard Quotient (HQ) of 0.2 shall be
				identified using the following equation:
[OHM]dw, non-cancer = HQ X RfD X BW X
				  C/(IR X RAFdw-oral).
Where:
[OHM]dw, non-cancer = Concentration of
				  oil and/or hazardous material consistent with a non-cancer Hazard Quotient of
				  0.2, in units of micrograms per liter (µg/L or ppb).
HQ = Hazard Quotient of 0.2 (dimensionless).
RfD = Reference Dose, in units of milligrams per kilogram-day
				  (mg/(kg X d)).
BW = Body weight of 70 kilograms (kg).
C = Conversion factor of 1000 micrograms per milligram
				  (µg/mg).
IR = Intake rate of 2 liters of water per day.
RAFdw-oral = Relative Absorption
				  Factor for oral drinking water exposures (dimensionless).
(b) A concentration of the oil and/or
				hazardous material associated with an Excess Lifetime Cancer Risk equal to
				one-in-one million shall be identified using the following equation:
[OHM]dw, cancer = ELCR X C x BW/(IR x
				  RAF x CSF).
Where:
[OHM]dw, cancer = The concentration of
				  oil and/or hazardous material in groundwater consistent with a cancer risk
				  limit of one-in-one million, in units of micrograms per liter (µg/L or
				  ppb).
ELCR = The Method 1 Excess Lifetime Cancer Risk limit of
				  one-in-one million (10-6).
C = Conversion factor of 1000 micrograms per milligram
				  (µg/mg).
BW = Body weight of 70 kilograms (kg).
IR = Intake rate of 2 liters of water per day.
RAFdw-oral = Relative Absorption
				  Factor for oral drinking water exposures (dimensionless).
CSF = Cancer Slope Factor in units of risk per milligrams per
				  kilogram-day (mg/(kg x day))-1.
(c) The concentration in water of the oil
				and/or hazardous material at which 50% of the population can detect its odor is
				identified, if available;
(d) The
				lowest non-zero concentration estimated in 310 CMR 40.0983(2)(a), (b), and (c)
				is identified as the risk-based concentration for the oil and/or hazardous
				material of concern;
(e) The
				site-specific groundwater background concentration identified for the oil
				and/or hazardous material in 310 CMR 40.0983(1) is considered;
(f) The Practical Quantitation Limit (PQL)
				applicable to the oil and/or hazardous material using an appropriately
				sensitive analytical method for quantifying the concentration of the oil and/or
				hazardous material in water shall be identified; and
(g) The highest of the three concentrations
				identified in 310 CMR 40.0983(2)(d), (e) and (f) is adopted as the MCP Method 2
				GW-1 Standard for that oil and/or hazardous material.