Table 1.

ICRP equivalent dose limits and NCRP numeric protection criteria for the lens of the eye

	ICRP		NCRP
	Past	Present	Past	Present
Occupational exposure	150 mSv/year (1980–2011)	100 mSv/5 years (≤50 mSv/year) (2011–)	150 mSv/year (1987–2016)	50 mGy/year (2016–)
Public exposure	50 mSv/year (1970–1990)	15 mSv/year (1990–)	15 mSv/year (1993–2016)	15 mGy/year (2016–)
Threshold	>8 Sva	0.5 Gy (2011–)	4 Gyb	N.A. (2016–)
Radiation weighting	${\displaystyle \overline{\mathrm{Q}}}$(1973–1990)	wR (1990–)	wR (1993–2016)	RBE (2016–)

ICRP, International Commission on Radiological Protection;N.A., not available due to uncertainty; NCRP, US National Council on Radiation Protection and Measurements; ${\displaystyle \overline{\mathrm{Q}}}$, effective quality factor; RBE, relative biological effectiveness; VIC, vision impairing cataract; w_R, radiation weighting factor.

^aFor highly fractionated/protracted exposures:>8 Sv for VICs and 5 Sv for detectable opacities. For acute exposure: 5 (2–10) Sv for VICs and 0.5–2 Sv for detectable opacities. The “150 mSv/year limit” was obtained by rounding off “>160 mSv/year” calculated as >8 Sv divided by working life of 50 years.

^bFor cataracts: 4 Gy for fractionated exposures and 2–10 Gy for acute exposure.