§ 141.50 - Maximum contaminant level goals for organic contaminants.

§ 141.50 Maximum contaminant level goals for organic contaminants.

Cross Reference

Link to an amendment published at 89 FR 32744, Apr. 26, 2024.

(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:

Contaminant	MCLG in mg/l (unless otherwise noted)
(1) 1,1-Dichloroethylene	0.007
(2) 1,1,1-Trichloroethane	0.20
(3) para-Dichlorobenzene	0.075
(4) Aldicarb	0.001
(5) Aldicarb sulfoxide	0.001
(6) Aldicarb sulfone	0.001
(7) Atrazine	0.003
(8) Carbofuran	0.04
(9) o-Dichlorobenzene	0.6
(10) cis-1,2-Dichloroethylene	0.07
(11) trans-1,2-Dichloroethylene	0.1
(12) 2,4-D	0.07
(13) Ethylbenzene	0.7
(14) Lindane	0.0002
(15) Methoxychlor	0.04
(16) Monochlorobenzene	0.1
(17) Styrene	0.1
(18) Toluene	1
(19) 2,4,5-TP	0.05
(20) Xylenes (total)	10
(21) Dalapon	0.2
(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-DA	0.00001.
(36) PFHxS	0.00001.
(37) PFNA	0.00001.

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-DA_water ng/l]/[10 ng/l]) + ([PFBS_water ng/l]/[2000 ng/l]) + ([PFNA_water ng/l]/[10 ng/l]]) + ([PFHxS_water ng/l]/[10 ng/l])

HBWC = health-based water concentration

HQ = hazard quotient

ng/l = nanograms per liter

PFAS_water = the concentration of a specific PFAS in water

[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, April 25, 2024]