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Maximum Contaminant Levels for Water

The U. S. Environmental Protection Agency (USEPA) regulates the concentration of radioactivity in public drinking water systems (i.e., those that are publicly- or privately-owned, serve at least 25 people or 15 service connections for at least 60 days per year). To protect public health, the USEPA has established maximum contaminant levels (MCLS) for several types of radioactive contaminants in drinking water (40 CFR 141).  For combined radium (i.e., Ra-226/228) the  MCL is five (5) picocuries per liter.  For gross alpha activity, the MCL is 15 picocuries per liter.  For uranium, it is 30 micrograms per liter.

For beta emitters, the MCL is a concentration which produces an annual radiation dose of four (4) millirem effective dose equivalent in one year (65 FR 76708).  The MCLs are calculated assuming a two (2) liter per day water intake using the 168-hour maximum permissible concentration (MPC) listed in a 1963-vintage NBS Handbook that used a “critical organ” philosophy (i.e., NBS Handbook 69).

The following is a listing of the derived concentrations of beta and photon emitters in drinking water, units of picocuries per liter (pCi/l) that yields an effective dose equivalent of four (4) millirem based upon the NBS Handbook 69 factors.  If multiple radionuclides are present, compliance should be demonstrated using the “unity rule”.

Antimony

  • Sb-122 – 90
  • Sb-124 – 60
  • Sb-125 – 300

Arsenic

  • As-73 – 1,000
  • As-74 – 100
  • As-76 – 60
  • As-77 – 200

Barium

  • Ba-131 – 600
  • Ba-140 – 90

Berkelium

  • Bk-249 – 2,000

Beryllium

  • Be-7 – 6,000

Bismuth

  • Bi-206 – 100
  • Bi-207 – 200

Bromine

  • Br-82 – 100

Cadmium

  • Cd-109 – 600
  • Cd-115 – 90
  • Cd-115m – 90

Calcium

  • Ca-45 – 10
  • Ca-47 – 80

Carbon

  • C-14 – 2,000

Cerium

  • Ce-141 – 300
  • Ce-143 – 100
  • Ce-144 – 30

Chlorine

  • CI-36 – 700
  • CI-38 – 1,000

Cobalt

  • Co-57 – 1,000
  • Co-58 – 300
  • Co-58m – 9,000
  • Co-60 – 100

Cromium

  • Cr-51 – 6,000

Cesium

  • Cs-131 – 20,000
  • Cs-134 – 80
  • Cs-134m – 20,000
  • Cs-135 – 900
  • Cs-136 – 800
  • Cs-137 – 200

Copper

  • Cu-64 – 900

Dysprosium

  • Dy-165 – 1,000
  • Dy-166 – 100

Erbium

  • Er-169 – 300
  • Er-171 – 300

Europium

  • Eu-152 – 200
  • Eu-154 – 60
  • Eu-155 – 600

Fluorine

  • F-18 – 2,000

Iron

  • Fe-55 – 2,000
  • Fe-59 – 200

Gallium

  • Ga-72 – 100

Gadolinium

  • Gd-153 – 600
  • Gd-159 – 200

Germanium

  • Ge-71- 6,000

Gold

  • Au-196 – 600
  • Au-198 – 100
  • Au-199 – 600

Hafnium

  • Hf-181 – 200

Holmium

  • Ho-166 – 90

Hydrogen

  • H-3 – 20,000

Indium

  • In-113m – 3,000
  • In-114m – 60
  • In-115 – 300
  • In-115m – 1,000

Iridium

  • Ir-190 – 600
  • Ir-192 – 100
  • Ir-194 – 90

Potassium

  • K-42 – 900

Iodine

  • l-126 – 3
  • l-129 – 1
  • l-131 – 3
  • l-132 – 90
  • l-133 – 10
  • l-134 – 100
  • l-135 – 30

Lanthanum

  • La-140 – 60

Lutetium

  • Lu-177 – 300

Manganese

  • Mn-52 – 90
  • Mn-54 – 300
  • Mn-56 – 300

Mercury

  • Hg-197 – 900
  • Hg-197m – 600
  • Hg-203 – 60

Molybdenum

  • Mo-99 – 600

Neodymium

  • Nd-147 – 200
  • Nd-149 – 900

Neptunium

  • Np-239 – 300

Nickle

  • Ni-59 – 300
  • Ni-63 – 50
  • Ni-65 – 300

Niobium

  • Nb-93m 1,000
  • Nb-95 – 300
  • Nb-97 – 3,000

Osmium

  • Os-185 – 200
  • Os-191 – 600
  • Os-191m – 9,000
  • Os-193 – 200

Phosphorus

  • P-32 – 30

Protactinium

  • Pa-230 – 600
  • Pa-233 – 300
  • Pb-203 – 1,000

Palladium

  • Pd-103 – 900
  • Pd-109 – 300

Promethium

  • Pm-147 – 600
  • Pm-149 – 100

Praseodymium

  • Pr-142 – 90
  • Pr-143 – 100

Platinum

  • Pt-191 – 300
  • Pt-193 – 3,000
  • Pt-193m – 3,000
  • Pt-197 – 300
  • Pt-197m – 3,000

Plutonium

  • Pu-241 – 300

Rubidium

  • Rb-86 – 600
  • Rb-87 – 300

Rhenium

  • Re-186 – 300
  • Re-187 – 9,000
  • Re-188 – 200

Rhodium

  • Rh-103m – 30,000
  • Rh-105 – 300

Ruthineum

  • Ru-103 – 200
  • Ru-105 – 200
  • Ru-106 – 30
  • Ru-97 – 1,000

Sulfur

  • S-35 inorg – 500

Samarium

  • Sm-151 – 1,000
  • Sm-153 – 200

Scandium

  • Sc-46 – 100
  • Sc-47 – 300
  • Sc-48 – 80

Selenium

  • Se-75 – 900

Silicon

  • Si-31 – 3,000

Silver

  • Ag-105 – 300
  • Ag-110m – 90
  • Ag-111 – 100

Sodium

  • Na-22 – 400
  • Na-24 – 600

Strontium

  • Sr-85 – 900
  • Sr-85m – 20,000
  • Sr-89 – 20
  • Sr-90 – 8
  • Sr-91 – 200
  • Sr-92 – 200

Tantalum

  • Ta-182 – 100

Terbium

  • Tb-160 – 100

Technetium

  • Tc-96 – 300
  • Tc-96m – 30,000
  • Tc-97 – 6,000
  • Tc-97m – 1,000
  • Tc-99 – 900
  • Tc-99m – 20,000

Tellurium

  • Te-125m – 600
  • Te-127 – 900
  • Te-127m – 200
  • Te-129 – 2,000
  • Te-129m – 90
  • Te-131m – 200
  • Te-132 – 90

Thallium

  • Tl-200 – 1,000
  • Tl-201 – 900
  • Tl-202 – 300
  • Tl-204 – 300

Thulium

  • Tm-170 – 100
  • Tm-171 – 1,000

Tin

  • Sn-113 – 300
  • Sn-125 – 60

Tungsten

  • W-181 – 1,000
  • W-185 – 300
  • W-187 – 200

Vanadium

  • V-48 – 90

Yttrium

  • Y-90 – 60
  • Y-91 – 90
  • Y-91m – 9,000
  • Y-92 – 200
  • Y-93 – 90

Ytterbium

  • Yb-175 – 300

Zinc

  • Zn-65 – 300
  • Zn-69 6,000
  • Zn-69m – 200

Zirconium

  • Zr-93 – 2,000
  • Zr-95 – 200
  • Zr-97 – 60