Statutes, codes, and regulations
Code of Federal Regulations
Title 40 - PROTECTION OF ENVIRONMENTChapter I - ENVIRONMENTAL PROTECTION AGENCYSubchapter D - WATER PROGRAMSPart 141 - NATIONAL PRIMARY DRINKING WATER REGULATIONS
Subpart F - MAXIMUM CONTAMINANT LEVEL GOALS AND MAXIMUM RESIDUAL DISINFECTANT LEVEL GOALS
Section 141.50 - Maximum contaminant level goals for organic contaminants

40 C.F.R. § 141.50

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Current through September 30, 2024
Section 141.50 - Maximum contaminant level goals for organic contaminants
(a) MCLGs are zero for the following contaminants:
(1) Benzene.
(2) Vinyl chloride.
(3) Carbon tetrachloride.
(4) 1,2-dichloroethane.
(5) Trichloroethylene.
(6) Acrylamide.
(7) Alachlor.
(8) Chlordane.
(9) Dibromochloropropane.
(10) 1,2-Dichloropropane.
(11) Epichlorohydrin.
(12) Ethylene dibromide.
(13) Heptachlor.
(14) Heptachlor epoxide.
(15) Pentachlorophenol.
(16) Polychlorinated biphenyls (PCBs).
(17) Tetrachloroethylene.
(18) Toxaphene.
(19) Benzo[a]pyrene.
(20) Dichloromethane (methylene chloride).
(21) Di(2-ethylhexyl)phthalate.
(22) Hexachlorobenzene.
(23) 2,3,7,8-TCDD (Dioxin).
(24) PFOA.
(25) PFOS.
(b) MCLGs for the following contaminants are as indicated:

ContaminantMCLG in mg/l (unless otherwise noted)
(1) 1,1-Dichloroethylene0.007
(2) 1,1,1-Trichloroethane0.20
(3) para-Dichlorobenzene0.075
(4) Aldicarb0.001
(5) Aldicarb sulfoxide0.001
(6) Aldicarb sulfone0.001
(7) Atrazine0.003
(8) Carbofuran0.04
(9) o-Dichlorobenzene0.6
(10) cis-1,2-Dichloroethylene0.07
(11) trans-1,2-Dichloroethylene0.1
(12) 2,4-D0.07
(13) Ethylbenzene0.7
(14) Lindane0.0002
(15) Methoxychlor0.04
(16) Monochlorobenzene0.1
(17) Styrene0.1
(18) Toluene1
(19) 2,4,5-TP0.05
(20) Xylenes (total)10
(21) Dalapon0.2
(22) Di(2-ethylhexyl)adipate.4
(23) Dinoseb.007
(24) Diquat.02
(25) Endothall.1
(26) Endrin.002
(27) Glyphosate.7
(28) Hexachlorocyclopentadiene.05
(29) Oxamyl (Vydate).2
(30) Picloram.5
(31) Simazine.004
(32) 1,2,4-Trichlorobenzene.07
(33) 1,1,2-Trichloroethane.003
(34) Hazard Index PFAS (HFPO-DA, PFBS, PFHxS, and PFNA)1 (unitless).1
(35) HFPO-DA0.00001.
(36) PFHxS0.00001.
(37) PFNA0.00001.

1 The PFAS Mixture Hazard Index (HI) is the sum of component hazard quotients (HQs), which are calculated by dividing the measured component PFAS concentration in water by the corresponding contaminant's health-based water concentration (HBWC) when expressed in the same units (shown in ng/l). The HBWC for PFHxS is 10 ng/l; the HBWC for HFPO-DA is 10 ng/l; the HBWC for PFNA is 10 ng/l; and the HBWC for PFBS is 2000 ng/l. A PFAS Mixture Hazard Index greater than 1 (unitless) indicates an exceedance of the health protective level and indicates potential human health risk from the PFAS mixture in drinking water.

Hazard Index = ([HFPO-DAwater ng/l]/[10 ng/l]) + ([PFBSwater ng/l]/[2000 ng/l]) + ([PFNAwater ng/l]/[10 ng/l]]) + ([PFHxSwater ng/l]/[10 ng/l])

HBWC = health-based water concentration

HQ = hazard quotient

ng/l = nanograms per liter

PFASwater = the concentration of a specific PFAS in water

40 C.F.R. §141.50

50 FR 46901, Nov. 13, 1985, as amended at 52 FR 20674, June 2, 1987; 52 FR 25716, July 8, 1987; 56 FR 3592, Jan. 30, 1991; 56 FR 30280, July 1, 1991; 57 FR 31846, July 17, 1992
89 FR 32744, 6/25/2024