The lens of the eye is one of the more sensitive tissues in the body to radiation, especially related to forming cataracts. The current NRC dose limit for the eye is 15 rem in a year, which is lower than the limits for other single organs. (The unit “rem” is used to measure the amount of radiation you get from a source – 0.1 rem is the average amount each of us gets each year from naturally occurring radiation.)
Now, the International Commission on Radiological Protection (ICRP) has found that the eye is more sensitive than previously thought. Based on this, the ICRP has recommended a new lower dose limit for the lens of the eye. The new recommendation is two rem a year, averaged over the course of five years, with no single year exceeding five rem. Copies of the ICRP statement are available on the NRC website.
While the best current evidence is that no one in the U.S. has been receiving exposure to the lens of the eye at levels close to our current limits, some people working with radiation are getting exposures at, or slightly above, the new international recommendations.
We at NRC have been talking with licensees and other stakeholders for the past two years about possible changes to our radiation protection regulations as part of a process to ask for early input related to radiation protection rulemaking. These new international recommendations for limits to the lens of the eye are yet another issue that we need to consider.
To continue talking with stakeholders, we published a notice soliciting stakeholder input in the Federal Register on August 31, 2011. The notice gives background on the issue, and asks questions about the different ways in which a change might be written, and the kinds of impacts that might occur if a change was made. The Federal Register notice can also be accessed from the the NRC website at: http://www.nrc.gov/about-nrc/regulatory/rulemaking/potential-rulemaking/opt-revise.html
We welcome comments from all of those interested in the issue. Comments are due by October 31, 2011. The notice describes different ways in which comments can be sent to us.
Based on the comments received, we will be preparing a paper for Commission consideration that will include options for how the agency may proceed. So, please let us know – what should we do to see clearly?Donald A. Cool, Ph.D. Senior Advisor, Radiation Safety and International Liaison