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Nomenclature changes to part 141 appear at 69 FR 18803, Apr. 9, 2004.
(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-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
[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]
(a) [Reserved]
(b) MCLGs for the following contaminants are as indicated:
| Contaminant | MCLG (mg/l) |
|---|---|
| Antimony | 0.006 |
| Arsenic | zero 1 |
| Asbestos | 7 Million fibers/liter (longer than 10 µm). |
| Barium | 2 |
| Beryllium | .004 |
| Cadmium | 0.005 |
| Chromium | 0.1 |
| Copper | 1.3 |
| Cyanide (as free Cyanide) | .2 |
| Fluoride | 4.0 |
| Lead | zero |
| Mercury | 0.002 |
| Nitrate | 10 (as Nitrogen). |
| Nitrite | 1 (as Nitrogen). |
| Total Nitrate + Nitrite | 10 (as Nitrogen). |
| Selenium | 0.05 |
| Thallium | .0005 |
| 1 This value for arsenic is effective January 23, 2006. Until then, there is no MCLG. | |
[50 FR 47155, Nov. 14, 1985, as amended at 52 FR 20674, June 2, 1987; 56 FR 3593, Jan. 30, 1991; 56 FR 26548, June 7, 1991; 56 FR 30280, July 1, 1991; 57 FR 31846, July 17, 1992; 60 FR 33932, June 29, 1995; 66 FR 7063, Jan. 22, 2001]
(a) MCLGs for the following contaminants are as indicated:
| Contaminant | MCLG |
|---|---|
| (1) Giardia lamblia | zero |
| (2) Viruses | zero |
| (3) Legionella | zero |
| (4) Total coliforms (including fecal) | zero |
| coliforms and Escherichia coli | |
| (5) Cryptosporidium | zero |
| (6) Escherichia coli (E. coli) | zero |
(b) The MCLG identified in paragraph (a)(4) of this section is applicable until March 31, 2016. The MCLG identified in paragraph (a)(6) of this section is applicable beginning April 1, 2016.
[78 FR 10347, Feb. 13, 2013]
MCLGs for the following disinfection byproducts are as indicated:
| Disinfection byproduct | MCLG (mg/L) |
|---|---|
| Bromodichloromethane | zero |
| Bromoform | zero |
| Bromate | zero |
| Chlorite | 0.8 |
| Chloroform | 0.07 |
| Dibromochloromethane | 0.06 |
| Dichloroacetic acid | zero |
| Monochloroacetic acid | 0.07 |
| Trichloroacetic acid | 0.02 |
[63 FR 69465, Dec. 16, 1998, as amended at 65 FR 34405, May 30, 2000; 71 FR 478, Jan. 4, 2006]
MRDLGs for disinfectants are as follows:
| Disinfectant residual | MRDLG(mg/L) |
|---|---|
| Chlorine | 4 (as Cl 2). |
| Chloramines | 4 (as Cl 2). |
| Chlorine dioxide | 0.8 (as ClO2) |
[63 FR 69465, Dec. 16, 1998]
MCLGs for radionuclides are as indicated in the following table:
| Contaminant | MCLG |
|---|---|
| 1. Combined radium-226 and radium-228 | Zero. |
| 2. Gross alpha particle activity (excluding radon and uranium) | Zero. |
| 3. Beta particle and photon radioactivity | Zero. |
| 4. Uranium | Zero. |
[65 FR 76748, Dec. 7, 2000]