Recommendations

Risk Values and Dose Limits for ICRP 60 and NCRP 116

Recommendations, Risk Values and Other Factors	ICRP Publication 60	NCRP 116
Assumed Radiation Risks
Workers	4.0 x 10^-2 Sv^-1 for fatal cancer	4.0 x 10^-2 Sv^-1 for fatal cancer
	0.8 x 10^-2 Sv^-1 for nonfatal cancer detriment	0.8 x 10^-2 Sv^-1 for nonfatal cancer detriment
	0.8 x 10^-2 Sv^-1 for severe genetic effects	0.8 x 10^-2 Sv^-1 for severe genetic effects
Members of the Public	5.0 x 10^-2 Sv^-1 for fatal cancer	5.0 x 10^-2 Sv^-1 for fatal cancer
	1.0 x 10^-2 Sv^-1 for nonfatal cancer	1.0 x 10^-2 Sv^-1 for nonfatal cancer
	1.3 x 10^-2 Sv^-1 for severe genetic effects	1.3 x 10^-2 Sv^-1 for severe genetic effects
Embryo-fetus	not specifically stated	~10 x 10^-2Sv^-1
Occupational Dose Limits
Based on Stochastic Effects	50 mSv annual effective dose limit and 100 mSv in 5 y cumulative effective dose limit^c	50 mSv annual effective dose limit and 10 mSv x age (y) cumulative effective dose limit^c
Based on Deterministic Effects	150 mSv equivalent dose to lens of eye and 500 mSv annual equivalent dose limit to the skin, hands and feet^d	150 mSv annual equivalent dose to lens of eye and 500 mSv annual equivalent dose limit to the skin, hands and feet^d
Annual Limit on Intake (ALI)	20 mSv E (50) Bq^-1	^_
Annual Reference Levels on Intake (ARLI)	^_	20 mSv E (50) Bq^-1
Public Dose Limits^b
Based on Stochastic Effects	1 mSv annual effective dose limit and, if needed, higher values provided that the annual average over 5 y does not exceed 1 mSv^c	1 mSv annual effective dose limit for continuous exposure, and 5 mSv annual effective dose limit for infrequent exposure^c
Based on Deterministic Effects	15 mSv annual effective dose limit to lens of eye and 50 mSv annual equivalent dose limit to skin, hands, and feet^d	50 mSv annual equivalent dose limit to skin, and extremities^d
Embyo-fetus	2 mSv equivalent dose to the women's abdomen once pregnancy has been declared and limitaing intakes of radionuclides to about 1/20 of an ALI^d	0.5 mSv equivalent dose limit in a month once the pregnancy is known^d
Negligible Individual Dose (NID)	_	0.01 mSv annual effective dose per source or practice^e

^bThe dose limits exclude medical and natural background exposures	^c The concepts of effective dose equivalent and effective dose are different	^d The concepts of equivalent dose and dose equivalent are also different
^e NID does not have a corresponding risk level

The difference between effective dose and effective dose equivalent and equivalent dose and dose equivalent

The equivalent dose (H_T) is conceptually different from the dose equivalent (H).

The dose equivalent (H) is based on the absorbed dose at a "point" in tissue which is weighted by a distribution of quality factors (Q) which are related to the LET distribution of the radiation at that point. NCRP 93 (1987)

The equivalent dose, on the other hand, is based on an average absorbed dose in a tissue or an organ (D_T) and weighted by the radiation weighting factor (W_R) for the radiation(s) impinging on the body or, in the case of internal emitters, the radiation emitted by the source. So the equivalent dose is the product of the average-absorbed dose (D_T,R) in a tissue or organ (T) due to radiation (R) and a radiation factor (W_R) for each radiation in question. The equivalent dose is used in NCRP 116. .

When irradiation is from radionuclides deposited in various tissues and organs, nonuniform or partial body exposures usually occur.

The effective dose (E) is intended to provide a means for handling non-uniform irradiation situations, as did the earlier dose equivalent.

The effective dose (E) is the sum of the weighted equivalent doses for all irradiated tissues or organs. The tissue weighting factor (W_T) takes into account the relative detriment to each organ and tissue including the different mortality and morbidity risks from cancer, the risk of severe hereditary effects for all generations, and the length of life lost due to these effects.

Depending on the half lives of the radionuclides, there will be effects over time from radiation doses. To account for the continuing irradiation of organs and tissues after intake, there is the commited dose concept.

The committed equivalent dose, H_T(t), is the time integral of the equivalent dose-rate in a specific tissue (T) following intake of a radionuclide into the body.

Unless specified otherwise, an integration time of 50 y after intake is recommended for the occupational dose, and 70 y for members of the public.

The committed effective dose E(t), for each internally deposited radionuclide is calculated by summing the products of the committed equivalent doses and appropriate W_T values for all tissues irradiated.

For radionuclides with an effective half-life, exceeding three months, the committed equivalent dose and the committed effective dose are greater than the equivalent or effective dose received in the year of intake because they reflect the dose that will be delivered in the future as well as that delivered in the year of intake.

The committed equivalent dose and the committed effective dose are appropriate for all routine radioprotection purposes and should be used, for example, for assessing compliance with the annual effective dose limits and for planning and design.

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Risk Values and Dose Limits for ICRP 60 and NCRP 116

The difference between effective dose and effective dose equivalent and equivalent dose and dose equivalent

The equivalent dose (HT) is conceptually different from the dose equivalent (H).

The dose equivalent (H) is based on the absorbed dose at a "point" in tissue which is weighted by a distribution of quality factors (Q) which are related to the LET distribution of the radiation at that point. NCRP 93 (1987)

When irradiation is from radionuclides deposited in various tissues and organs, nonuniform or partial body exposures usually occur.

The effective dose (E) is intended to provide a means for handling non-uniform irradiation situations, as did the earlier dose equivalent.

Depending on the half lives of the radionuclides, there will be effects over time from radiation doses. To account for the continuing irradiation of organs and tissues after intake, there is the commited dose concept.

The committed equivalent dose, HT(t), is the time integral of the equivalent dose-rate in a specific tissue (T) following intake of a radionuclide into the body.

Unless specified otherwise, an integration time of 50 y after intake is recommended for the occupational dose, and 70 y for members of the public.

The committed effective dose E(t), for each internally deposited radionuclide is calculated by summing the products of the committed equivalent doses and appropriate WT values for all tissues irradiated.

The committed equivalent dose and the committed effective dose are appropriate for all routine radioprotection purposes and should be used, for example, for assessing compliance with the annual effective dose limits and for planning and design.

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The equivalent dose (H_T) is conceptually different from the dose equivalent (H).

The committed equivalent dose, H_T(t), is the time integral of the equivalent dose-rate in a specific tissue (T) following intake of a radionuclide into the body.

The committed effective dose E(t), for each internally deposited radionuclide is calculated by summing the products of the committed equivalent doses and appropriate W_T values for all tissues irradiated.

Last Updated: