Regulatory Guide 8.13
| ML13350A220 | |
| Person / Time | |
|---|---|
| Issue date: | 03/31/1975 |
| From: | NRC/OSD |
| To: | |
| References | |
| RG-8.013 | |
| Download: ML13350A220 (4) | |
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U.S. NUCLEAR REGULATORY COMMISSION March 1975 RE Q ULAT Y GWU DE
OFFICE OF STANDARDS DEVELOPMENT
REGULATORY GUIDE 8.13 INSTRUCTION CONCERNING PRENATAL RADIATION EXPOSURE
A. INTRODUCTION
after conception, when a womaii may not be aware that she is pregnant, the National Council on Radiation Section 19.12 of 10 CFR Part 19 states that all Protection and Measurements (NCRP) recommended in individuals working in or frequenting any portion of a its Report No. 39 that special precautions be taken to restricted area must be instructed in the health pro- limit exposure when an occupationally expo'ed woman tection problcms associated with exposure to radioactive could be pregnant.
materials or radiation. This guide describes the instruc- tion that should be provided concerning biological risks
C. REGULATORY POSITION
to embryos or fetuses resulting from prenatal exposure.
Instruction to workers performed under § 19.12 should be given prior to assignment to work in a
B. DISCUSSION
restricted area. In providing instruction about health protection problems associated with radiation exposure, Since the Law of Bergonie and Tribondeau was female workers and those who may supervise or work published in 19061 it has been known that the sensitiv- with them should be given specific instruction about ity of cells to radiation damage is related to their prenatal exposure risks to the developing embryo and reproductive activity and inversely related to their fetus.
degree of differentiation. It follows that children could W.,," be expected to be more radiosensitive than adults, The instruction should ensure that the employees fetuses more radiosensitive than children, and embryos understand:
even more radiosensitive.
1. That the NCRP has recommended holding This principle has long been a factor in the prenatal occupational exposure to 0.5 rem or less during development of radiation exposure standards. Section the entire period of gestation; and
20.104 of 10 CFR Part 20 places different limits on minors than on adult workers. Specifically, it limits 2. The reasons for this recommendation.
anyone under the age of 18 to exposures not exceeding
10% of the limits for adult workers. The instruction should include the information provided in the Appendix to this guide. It should be A special situation arises when an occupationally presented to the employee, her supervisors, and her
, exposed woman is pregnant. Exposure of the abdomen co-workers both orally and in written for
m. Each person
- of such a worker to penetrating radiation from either should be given an opportunity to ask questions, and external or internal sources would also involve exposure each person should be asked to acknowledge in writing of the embtyo or fetus. Because a number of studies that the instruction has been received.
have indicated that the embryo or fetus, is more sensitive dthn an adult, particularly during the first three months
D. IMPLEMENTATION
Corjttes Rendus des Seances de I'Aeademie des Sciences. VoL The purpose of this section is to provide informa-
143, pp. 983-985, 1906. don to licensees regarding the use of this guide.
uSNRC REGULATORY GUIDES Comments should be Sent to the Seetelarv oft he Commissiaon. U S Nuttlest Aegelatony Catonrnition. WashingIton. VC. 20M.. Attention locketing ean Rflasototy Guides &to issued to desctibo and myakeavailable t to the oub) c 5ef.. Section.
oIttehade &rceptebt. to the MAC staff of itmplemtenting Wo.CtiC parts of the Caommhl,acoon, .#9tittions. to dtnefiteoltteCh.nose used by tif. rtaff in theh guidaessansuediolthievoollaviglo Wod divisaons.
euroi soxsocf~c problems of ocislootetd accidents. or to provide guitdance ittýegol Coons Ae~viso"y Guide* era ..ot substitutes to, *.q..tht-onC. and COtv1-6til.t I G. P,odoicts Wttt them, Is not ,acquired Mehd o ou.n ittfttot h~ c u O 2. Research an Toll Roesor*" I Transportation tthe guides rovtitbe occeotabte It they ptoodo a bros, ilat the foondinis rosti ttle to 3 FUG128611od Meeloatt Vlcod4.0 11.Oecupat~ooa1 "*S~til shot uisi,&we a# lon~tinuance of a petnit or h~eiposby the Cammistsoon 4 o ~i 1 Antitrust Ae,..i C. Commtittotn and sugge'stect'o for ttttpvereuthsnt t these 5.u'dwsat. encouteogtd Sit40l fit"@. end tedtvlls illo be fewined as sootoop.aft, to accommnodute eorn
~~fts "'d Ito JetlCtnow tot01I'oreton of eleeenence Hooee'.e
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9 Moaterials and PtessiPlotaee,,on 111.Genetal Copies Of Published girdhes mew be obtained by woollen *equest indicatin~g the l
tltri outdoe. ttece-ied viilithS.n400tov months Altm, t6 isuanarce. 0d1 be coer divisonsO devs,,., to the U S Nuclear Pogulostory Commsottton. Washington. D C
tl.,a~y~saut.teirelogot.n; the noeadto, ust&..I, t",soon 20W. Alfttent11 Oeiftfor.Office ol SteAdordo Developmen~t ENCLOSURE I
Except In those cases in which the licensee chooses working in or frequenting any portion of a restricted to propose an alternative method for complying with the area, and -those who may supervise or work with such portion of the Commission's regulations previously employees, concerning the health protection problems specified, the methods described herein should be used associated with prenatal radiation exposure.
after September 1, 1975, to instruct female employees APPENDIX TO REGULATORY GUIDE 8.13 POSSIBLE HEALTH RISKS TO CHILDREN OF WOMEN
WHO ARE EXPOSED TO RADIATION DURING PREGNANCY
.Some recent studies have shown that the risk of restricted area of the health protection problems asso- leukemia and other cancers in children increases if the ciated with radiation exposure. This instruction would in mother Is exposed to a significant amount of radiation many cases include information on the possible risks to during pregnancy. According to a report by the unborn babies. The regulations also state* that National Academy of Sciences, the incidence of licensees should keep radiation exposures as low as leukemia among children under 10 years of age in the practicable. According to the National Council on United States could rise from 3.7 cases in 10,000 Radiation Protection and Measurements, particular children to 5.6 cases in 10,000 children if the children efforts should be made to keep the radiation exposure of were exposed to I rem of radiation before birth (a an embryo or fetus at the very lowest practicable level
"rem" is a measure of radiation). The Academy has also during the entire period of pregnancy.
estimated that an equal number of other types of cancers could result from this level of radiation. Thus it is the responsibility of your employer to tuthough other scientific studies have shown a much take all practicable steps to reduce your radiation smaller effect from radiation, the Nuclear Regulatory exposure. Then it is your responsibility to decide Commission wants women employees of its licensees to whether the exposure you are receiving is sufficiently be aware of any possible risk so that the women can take low to protect your unborn child. The advice of your steps they think appropriate to protect their offspring. employer's health physicist or radiation protection officer should be obtained to determine whether radia- As an employee of a Nuclear Regulatory Commis- tion levels in your working areas are high enough that a Sion licensee, you may be exposed to more radiation baby could receive 0.5 rem or more before birth. If so, than the general public. However, the Nuclear Regula- the alternatives that you might want to consider are:
tory Commission has established a basic exposure limit for all occupationally exposed adults of 1.25 reins per calendar quarter, or 5 reins per year. No clinical evidence (a) If you are now pregnant or expect to be soon, of harm would be expected in an adult working within you could decide not to accept or continue assignments these levels for a lifetime. Because the risks of undesir- in these areas.
able effects may be greater for young p)eople, persons under 18.years of age are permitted to be exposed to (b) You could reduce your exposure, where only 10 percent of the adu!. occupational limits. (This possible, by decreasing the amount of time you spend in lower limit is also applied to members of the general the radiation area, increasing your distance from the public.) radiation source, and using shielding.
The scientific organization called the National Council on Radiation Protection and Measurements has (c) If you do become pregnant, you could ask your recommended that because unborn babies may be more employer to reassign you to areas involving less exposure sensitive to radiation than adults, their radiation dose as to radiation. If this is not possible, you might consider a result of occupational exposure of the mother should leaving your job. If you decide to take such steps, do so not exceed 0.5 rem. Other scientific groups, including without delay. The unborn child is most sensitive to the International Commission on Radiation Protection, radiation during the first three months of your preg.
have also stressed the need to keep radiation doses to nancy.
unborn children as low as practicable.
(d) You could delay having children until you are All Nuclear Regulatory Cornnii&sion li'ensees are no longer working in an area where the radiation dose to now required* to inform all Individuals who work in a your unborn baby could exceed 0.5 rem.
- By Title 10. Part 19 of the Code of Federai Regulations. "In Title 10, Part 20.
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You may also, of course, choose to: 0.072 rem per year. The average dose from one chest X-ray is 0.045 rem.
(e) Continue working in the higher radiation areas, but with full awareness that you are doing so at some Radiation can also be received from natural sources small increased risk for your unborn child. such as rock or brick structures, front consumer pro- ducts such as television and glow-in-the-dark watches, The following facts should be noted to help you make a and from air travel. The possible annual dose from decision: working 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> a day near a granite wall at the Redcap Stand in Grand Central Station, New York City, is 0.2
1. The first three months of pregnancy are the rem, and the average annual dose in the United States most important, so you should make your decision from TV, consumer products, and air travel is 0.0026 quickly. rem.
2. At the present occupational exposure limit, the Radiation, like many things, can be harmful. A large actual risk to the unborn baby is small, but experts dose to the whole body (such as 600 reins in one day)
disagree on the exact amount of risk. would probably cause death in about 30 days, but such large doses result only from rare accident
s. Control of
3. There is no need to be concerned about sterility exposure to radiation is based on the assumption that or loss of your ability to bear children. The radiation any exposure, no matter how small, involves some risk.
dose required to produce such effects is more than 100 The occupational exposure limits are set so low, how- times larger than the Nuclear Regulatory Commission's ever, that medical evidence gathered over the past 50
dose limits for adults. years indicates no clinically observable injuries to indi- viduals due to radiation exposures when the established
4. Even if you work in an area where you receive radiation limits are not exceeded. This was true even for only 0.5 rem per three-month period, in nine months exposures received under the early occupational ex- you could receive 1.5 reins, which exceeds the full-term posure limits, which were many times higher than the limit suggested by the NCRP. Therefore, if you d&cide to present limits. Thus the risk to individuals at the restrict your unborn baby's exposure as recommended occupational exposure levels is considered to be very by the NCRP, be aware that the 0.5 rem limit applies to low. However, it is impossible to say that the risk is zero.
- the full nine-month pregnancy. To decrease the risk still further, licensees are expected to keep actual exposures as far below the limits as
- The remainder of this document contains a brief practicable.
explanation of radiation and its effects on humans. As you will see, some radiation is present everywhere and The current exposure limits for people working with the levels of radiation most employees of Nuclear radiation have been developed and carefully reviewed by Regulatory Commission licensees receive are not much nationally and internationally recognized groups of larger than these natural levels. Because the radiation scientists. It must be remembered, however, that these levels in the facility where you will be working are limits are for adults. Special consideration is appropriate required by law to be kept quite low, there is not when the person being exposed is, or may be, an considered to be a significant health risk to individual expectant mother, because the exposure of an unborn adult employees. child may also be involved.
Discussion of Radiation The amount of radiation a person receives is called Prenatal Irradiation the "dose" and is measured in "reins." The average peron in the United States gets a dose of one rem from The prediction that an unborn child would be more sensitive to radiation than an adult is supported by natural sources every 12 years. The dose from natural observations for relatively large doses. Large doses radiation is higher in some states, such as Colorado, delivered before birth alter both physical development Wyoming, and South Dakota, primarily because of and behavior in experimentally exposed animals. A
cosmic. radiation. There the average person gets one rem report of the National Academy of Sciences states that every 8 years.
short-term doses in the range of 10 to 20 reins cause Natural background radiation levels are also much subtle changes In the nerve cells of unborn and infant higher in certain local areas. A dose of one rem may be rats. The report also states, however, that no radiation- received in some areas on the beach at Guarapari, Brazil, induced changes in development have been demon- in only about 9 days, and some people in Kerala, India, strated to result In experimental animals from doses up get a dose of one rem every 5 months. to about I rem per day extended over a large part of the period before birth.
Many people receive additional radiation for
'C medical reasons. The annual radiation dose averaged over the United States population from diagnostic X.rays is The National Academy of Sciences also noted that doses of 25 to 50 reins to a pregnant human may cause
8.13-3
growth disturbances in her offspring. Such doses sub. Bibliography stantially exceed. of course, the maximum permissible Donald G. Pizzarello and Richard L. Witcofski, occupational exposure limits.
Basic Radiation Biology, Philadelphia: Lea and Concern about prenatal exposure (i.e., exposure of a Febizer. 1967.
child while in its mother's uterus) at the permissible occupational levels is primarily based on the possibility 2. National Academy of Sciences - National Research that cancer (especially leukemia) may develop during the Council, The Effccts on Populationsof Exposure to first 10 years of the child's life. Several studies have been Low Levels of Ioni:ing Radiation, Washington, performed to evaluate this risk. One study involved the D.C., November 1972.
followup of 77.000 children exposed to radiation before birth (because of diagnostic abdominal X-rays made for 3. National Council on Radiation Protection and medical purposes during their mother's pregnancy). Measurements. Basic Radiation Protection Criteria, Another stud)y involved the followup of 20.000 such NCRP Report No. 39, Washington, D.C., January children. In addition, 1292 children who received 15, 1971.
prenatal exposure during the bombing of Hiroshima and 4. United Nations. Ionizing Radiation: Levels and Nagasaki were studied. Although contradictory results Effects, 2 vol., Reports of the United Nations have been obtained, most of the evidence sugests a Scientific Committee on the Effects of Atomic relationship between prenatal exposure and an increased Radiation, Report No. A/8725, United Nations.
risk of childhood cancer. New York, 1972.
Summary
5. US. Atomic Energy Commission, Division of Occupational exposures to radiation arc being kept Technical Information, Understanding the Atom low. flowever, qualified scientists have recommended Series:
that the radiation dose to a pregn,,.nt woman should not exceed 0.5 rem because of possible risks to her unborn Atoms, Nature and Alan child. Since this 0.5 rem is lower than the dose generally permitted to adult workers, women may want to take The Genetic Effects of Radiation special actions to avoid receiving higher exposures, just as they might stop smoking during pregnancy or might The NaturalRadiation Environment climb stairs more carefully to reduce possible risks to their unborn children. Your Body and Radiation UNITED STATES
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