¹ MCL is the Maximun Contaminant Level. This is the permissible level of a contaminant in public water.
² MCLG is a Maximum Contaminant Level Goal. The level of a contaminant in public drinking water at which no known or anticipated adverse effect on the health of persons would occur, and allowing an adequate margin of safety. MCLGs are not enforceable.
³ TEDE is the Total-body Effective Dose Equivalent (also written EDE). A TEDE is a weighting factor for regulatory purposes that converts the dose received by an organ to a whole body dose.
Sources: For current concentrations, 41 FR (Federal Register) 28404, July 9, 1976. For proposed concentrations, 56 FR 33050, July 18, 1991.

SOIL (Current EPA and NRC Standards and Guidelines)
NUCLIDE		CONCENTRATION (picocuries/gram)		DESCRIPTION
		Option 1*	Option 2
Natural Thorium (Th-232 and Th-228) with daughters present and in equilibrium		10a	50b	NRC Guidelines
Natural Uranium (U-238 and U-234) with daughters present and in equilibrium		10c	-	NRC Guidelines
Depleted Uranium
o Soluble		35a	100b	NRC Guidelines
o Insoluble		35	300b	NRC Guidelines
Enriched Uranium
o Soluble		30a	100b	NRC Guidelines
o Insoluble		30	250b	NRC Guidelines
Transuranic elements		11 picocuries/gram		EPA Guidelines
Radium-226 in soils of inactive uranium mill areas		There are two required limits 1) 5 picocuries/gram in the first 15 cm of soil below the surface (in addition to background levels) 2) 15 picocuries/gram average in each layer of soil that is deeper than 15 cm thick 15 cm below the surface (in addition to background levels)		EPA Standards

*(NRC Action Plan has two options)
^a The concentrations of Natural Thorium, depleted and enriched uranium are based on limiting individual doses to 1 millirad per year to the lung and 3 millirad per year to the bones. These guidelines are used as guidelines by EPA for protection against transuranic elements in the environment.
^b Natural thorium decays into radium. For this reason, the maximum concentrations for this nuclide is based on the EPA standards for radium in mill areas, given at the bottom of the table.
^c These concentrations are based on limiting individual doses to 170 millirem per year if the buried material is disturbed.
Sources: 46 FR 52061, October 23, 1981; 42 FR 60956, November 30, 1977; 40 CFR 192.

SURFACE (Equipment and Building Surfaces, NRC Guidelines)
NUCLIDEa		CONCENTRATION (in disintegrations per minuteb / 100 square centimeters)c
		AVERAGEd	MAXIMUMe	REMOVABLE
Natural uranium, Uranium-235, Uranium-238, and associated decay products		5,000 alpha	15,000 alpha	1,000 alpha
Transuranics, Radium-226, Radium-228, Thorium-230, Thorium-228, Protactinium-231, Ac-227, Iodine-125, Iodine-129		100	300	20
Natural Thorium, Thorium-232, Strontium-90, Radium-223 Radium-224, Uranium-232 Iodine-126, Iodine-131 Iodine-133		1,000	3000	200
Beta-gamma emitters (nuclides with decay modes other than alpha emission or spontaneous fission) except Strontium-90 and others noted above.		5,000	15,000	1000

^a Where surface contamination by both alpha and beta-gamma emitting nuclides exists, the limits established for alpha and gamma emitting nuclides should apply independently.
^b As used in this table, dpm (disintregration per minute) means the rate of emission by radioactive material as determined by correcting the counts per minute observed by an appropriate detector for background, efficiency, and geometric factors associated with the instrumentation.
^c One picocurie is about 2 disintegrations per minute (dpm). 100 square centimeters is about 0.1 square foot.
^d Measurements of average contaminants should not be averaged over more than 1 m².
^e The maximum contamination levels applies to an area of no more than 100 cm².
Source: U.S. NRC. Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use of Termination of Licenses for Byproduct, Source, or Special Nuclear Material. Policy and Guidance Directive FC 83-23, Division of Industrial and Medical Nuclear Safety: Washington, DC, August 1987.