ICRP Publication 95. Doses to infants from radionuclides ingested in mothers’ milk

287 Pages·2.82 MB·English

ICRPPublication95
Doses to infants from radionuclides
ingested in mothers’ milk
ICRP Publication 95
Approved by the Commission in November 2004
Abstract–In the present report, ICRP provides information on radiation doses to the infant
duetointakesofradionuclidesinmaternalmilk.AsinPublication88(ICRP,2001)ondoses
tothe embryoandfetusfollowingintakes ofradionuclides bythemother, intakes byfemale
members of the public and female workers are addressed. Acute and chronic intakes are
considered at various times before and during pregnancy as well as during the period of
breastfeeding.Dosecoefficientsperunitintakebythemother(Sv/Bq)aregivenfortheselected
radionuclides ofthesame31elements forwhich age-specificbiokineticmodelsweregivenin
Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995a,b). For these elements, doses were
calculatedforthemostradiologicallysignificantnaturalorartificialradionuclidesthatmight
be released into the environment due to various human activities. Dose coefficients are also
given in this report for radionuclides of an additional four elements: sodium, magnesium,
phosphorus,and potassium.
Relevant human and animal data on elemental and radionuclide transfer to milk are
reviewed.ThebiokineticmodelsforadultsgiveninearlierICRPpublicationsareadaptedto
includetransfertomilk.Modelpredictionsoffractionaltransferofingestedorinhaledactivity
tomilkarediscussedinthereport,andthecorrespondingdosecoefficientsfortheinfantare
comparedwithdosecoefficientsforinuteroexposure,asgiveninPublication88(ICRP,2001).
Illustrativeinformationisalsogivenondosestothefemalebreastfromradionuclidesinbreast
milk,andexternaldosesreceivedbythechildfromradionuclidesretainedinthetissuesofthe
mother.Fortheadditionalelementsconsideredinthisreport,butnotinPublication88(ICRP,
2001),informationisalsogivenondosestotheembryoandfetusfollowingmaternalintakes
of radioisotopesduring orbeforepregnancy.
A CD-ROM isto be issuedgiving datathat will supplement the information givenin this
report.Inadditiontothedosecoefficientsgivenhere,committedequivalentdosestothevarious
organsandtissuesoftheoffspringwillbegiven.Dosecoefficientswillalsobegivenforinhalation
ofarangeofaerosolsizesfortheselectedradionuclidesoftheelementscoveredbythisreport.
(cid:1)2004ICRP.PublishedbyElsevierLtd.
Keywords:Dosecoefficient;Maternalintake;Milk;Infantdose;Ingestion;Inhalation
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CONTENTS
ABSTRACT...................................................................................................................................... iii
GUEST EDITORIAL.................................................................................................................. 1
PREFACE......................................................................................................................................... 5
GLOSSARY...................................................................................................................................... 9
1. INTRODUCTION................................................................................................................... 15
1.1. Background......................................................................................................................... 15
1.2. Pregnancy............................................................................................................................ 15
1.3. Lactation.............................................................................................................................. 17
1.4. Maternal intakes of radionuclides by ingestion or inhalation...................... 18
1.5. Intakes by the infant of radionuclides in breast milk...................................... 20
1.6. Dose coefficients............................................................................................................... 21
2. BREAST MILK......................................................................................................................... 23
3. MODEL DEVELOPMENT AND DOSE CALCULATIONS............................ 29
3.1. Introduction........................................................................................................................ 29
3.2. Intakes by the mother.................................................................................................... 29
3.3. Models for lactation........................................................................................................ 30
3.4. Treatment of decay products...................................................................................... 34
3.5. Dose coefficients for breastfeeding infants............................................................ 35
3.6. Dose to breast from activity secreted in milk...................................................... 36
3.7. Infant doses from radionuclides in the mother’s body.................................... 36
3.8. Dose coefficients for the embryo and fetus additional to those in
Publication 88..................................................................................................................... 36
4. DISCUSSION............................................................................................................................. 37
4.1. Introduction........................................................................................................................ 37
4.2. Transfer of radionuclides to milk............................................................................. 37
4.3. Dose coefficients............................................................................................................... 39
4.4. Conclusions......................................................................................................................... 45
5. BIOKINETIC DATA AND MODELS.......................................................................... 47
5.1. Hydrogen............................................................................................................................. 49
5.2. Carbon.................................................................................................................................. 52
5.3. Sodium.................................................................................................................................. 54
5.4. Magnesium.......................................................................................................................... 57
5.5. Phosphorus.......................................................................................................................... 60
5.6. Sulphur................................................................................................................................. 63
5.7. Potassium............................................................................................................................. 65
5.8. Calcium................................................................................................................................. 68
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5.9. Iron......................................................................................................................................... 74
5.10. Cobalt................................................................................................................................. 78
5.11. Nickel.................................................................................................................................. 81
5.12. Zinc...................................................................................................................................... 84
5.13. Selenium............................................................................................................................. 87
5.14. Strontium........................................................................................................................... 90
5.15. Zirconium.......................................................................................................................... 94
5.16. Niobium............................................................................................................................. 96
5.17. Molybdenum.................................................................................................................... 99
5.18. Technetium....................................................................................................................... 101
5.19. Ruthenium........................................................................................................................ 103
5.20. Silver.................................................................................................................................... 106
5.21. Antimony........................................................................................................................... 109
5.22. Tellurium........................................................................................................................... 113
5.23. Iodine.................................................................................................................................. 117
5.24. Caesium.............................................................................................................................. 124
5.25. Barium................................................................................................................................ 128
5.26. Cerium................................................................................................................................ 131
5.27. Lead..................................................................................................................................... 134
5.28. Polonium........................................................................................................................... 136
5.29. Radium............................................................................................................................... 138
5.30. Thorium............................................................................................................................. 142
5.31. Uranium............................................................................................................................. 146
5.32. Neptunium........................................................................................................................ 151
5.33. Plutonium.......................................................................................................................... 154
5.34. Americium......................................................................................................................... 158
5.35. Curium................................................................................................................................ 161
ANNEX A. DOSE COEFFICIENTS FOR OFFSPRING OF FEMALE
WORKERS....................................................................................................................................... 165
ANNEX B. BREAST DOSES FROM RADIONUCLIDES IN MILK.............. 213
ANNEX C. INFANT DOSES FROM RADIONUCLIDES IN THE
MOTHER.......................................................................................................................................... 229
ANNEX D. DOSE COEFFICIENTS FOR THE EMBRYO/FETUS:
RADIOISOTOPES OF SODIUM, MAGNESIUM, PHOSPHORUS, AND
POTASSIUM................................................................................................................................... 235
REFERENCES............................................................................................................................... 269
ICRPPublication95
Guest Editorial
LAST REPORT IN SERIES ON PUBLIC DOSES
Thispublicationondosestoinfantsfromradionuclidesinmothers(cid:1)milkisthelast
inaseries ondosestomembersofthepublic,although,togetherwithitsimmediate
predecessor on doses to the embryo and fetus, it is also applicable to occupational
exposures.TheseriesbeganwithPublication56(ICRP,1989)whichgavedosecoef-
ficientsforarangeofradionuclidesingestedbymembersofthepublic,includingin-
fantsandchildren,withsubsequentreportsgivingvaluesforotherradionuclidesand
considering inhalation as well as ingestion (ICRP, 1989, 1993, 1995b,c, 1996). Pub-
lication 88 (ICRP, 2001) gave dose coefficients for the embryo, fetus, and newborn
child from intakes of radionuclides by the mother before or during pregnancy.
The present report considers transfer of radionuclides to the infant in breast milk
for the intake times used in Publication 88 and additional times during lactation.
Itgivesdosecoefficientsforinfantsfollowingradionuclideintakesbytheirmothers,
withvaluesformembersofthepublicinthemaintextandvaluesforworkersinAn-
nex A. Annexes B and C give examples of doses to maternal breast tissue occurring
during radionuclide transfer, and external doses to the infant from radionuclides in
the mother(cid:1)s body, respectively. Annex D gives dose coefficients for the fetus for
some additional radionuclides not included in Publication 88 (ICRP, 2001).
Adeparturefrompreviouscustominthisreportisadiscussionofdoses(Chapter
4). The main conclusion reached is that for most of the radionuclides considered,
doses to the infant from radionuclides ingested in breast milk are estimated to be
smallincomparisonwithdosestothereferenceadult.Thiscomparisonismadewith
the reference adult because ICRP does not calculate doses separately for males and
females. Comparisons of infant doses with doses specific to female adults would re-
sult in different numerical values but the same general conclusions. On the basis of
the models developed in this report, it is only in the cases of tritiated water, 45Ca,
75Se, and 131I that infant doses may exceed adult doses, by ratios of between 1
and 3, applying to maximum transfer occurring after maternal intakes by ingestion
shortly after birth. Ratios of infant to reference adult doses are generally lower for
intakes by inhalation than for ingestion. Comparisons with Publication 88 (ICRP,
2001)dosestotheoffspringduetoinuteroexposuresshowthat,inmostcases,these
are more important than doses that may result from breastfeeding; exceptions in-
clude 60Co, 131I, and 210Po. The discussion of doses in this report is deliberately
short; further details will be published in the open literature, following an earlier
publication of preliminary results (Harrison et al., 2003). Doses to the embryo
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and fetus from 32P, given in this report, and from bone-seeking alkaline earth iso-
topes of calcium, strontium, and radium, as well as from iodine isotopes, given in
Publication88(ICRP,2001),canbesubstantiallygreaterthanthecorrespondingref-
erenceadultdoses.Thus,whiletheratiosofoffspringtoadultdosearelessthan1for
most radionuclides, those for 32P, for example, are around 10 or more for chronic
intakethroughoutpregnancyorsingleintakesfrom10weeksofpregnancy.Thefac-
torsdeterminingdosesfollowinginuteroexposuresarediscussedelsewhere(Stather
et al., 2002, 2003).
Calculationsofexternalphotondosestotheinfantfromradionuclidesinmaternal
tissues, using a modified voxel phantom, show that in some cases it is possible for
external dose to dominate the overall effective dose to the infant. This applies, for
example, to inhalation of insoluble 60Co by the mother, while for other examples
considered in the report, external dose is small compared with the dose resulting
from radionuclides ingested in breast milk.
Having completed this series of publications primarily concerned with public
exposures, the emphasis of Committee 2(cid:1)s work on internal dosimetry has now
turnedtooccupationalexposure.Acomprehensiverevisionofadviceondoseassess-
mentandmonitoring foroccupationalintakesofradionuclidesisbeingprepared.It
is intended to replace Publications 30, 54, 68, and 78 (ICRP, 1979, 1980, 1981,
1988a,b, 1994b, 1997b) by a series of publications that will cover both dosimetry
and the interpretation of bioassay measurements. The first report will cover radio-
nuclidesofthe31elementscoveredinPublication56(ICRP,1989);subsequentpub-
lications will cover additional elements.
ThisseriesofpublicationswilltakeaccountofnewrecommendationsbytheCom-
mission on tissue-weighting factors. It will incorporate an update of nuclear decay
data being prepared (Endo et al., 2003, 2004) as a replacement for Publication 38
(ICRP, 1983a). It will be the first implementation of a new human alimentary tract
model.InapplyingthehumanrespiratorytractmodelgiveninPublication66(ICRP,
1994a), inhaled radionuclides will be assigned to the default absorption types based
onareviewofcurrentinformation,andspecificparametervaluesarealsotobepro-
posed for some compounds. A comprehensive review of the biokinetic models for
systemic activity is underway. A central feature of the review is the need to provide
modelsthatareappropriateforbothprospectivedosimetryandbioassayinterpreta-
tion.Thenewpublicationwillalsousenewvaluesforspecificabsorbedfractionsob-
tained from modelling studies with voxel phantoms (Fill et al., 2004; Zankl et al.,
2003); both male and female voxel phantoms are being developed and will replace
the current mathematical phantom presently used for dose calculations. It will also
apply updated reference anatomical and physiological data given in Publication 89
(ICRP, 2002b).
These publications on occupational intakes of radionuclides will be accompanied
by a Supporting Guidance Document that will give more comprehensive advice on
theassessmentofintakesanddosesfrombioassaydata.Itsaimsaretopromotehar-
monisation of internal dose assessment, to make best use of the available data, and
to apply effort in assessments in proportion to the likely doses involved. The devel-
opment of this document will draw from work carried out in a research project
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(cid:2)Generalguidelines for the estimation of committed doses from incorporation mon-
itoring data(cid:1) (acronym IDEAS) supported by the European Union that has exam-
ined how to improve the assessment of bioassay data.
Returning to this report and the related Publication 88 (ICRP, 2001) on in utero
exposures, the doses calculated in these publications raise issues for the control of
both public and occupational exposures. Clearly for those radionuclides for which
the child(cid:1)s dose can exceed the adult dose, it may be insufficient to base protection
on doses to the mother alone. Consideration will need to be given to circumstances
in which these routes of exposure should be included in critical group dose assess-
ments,andinwhichadditionaladvicewillberequiredconcerningworkwithspecific
radionuclides.
JOOHHNN HAARRRRIISSOONN
ALLAANN PHHIIPPPPSS
JOOHHNN STTAATTHHEERR
3

PREFACE
In 1987, the International Commission on Radiological Protection (ICRP) estab-
lished a Task Group of Committee 2 on Internal Dosimetry to develop age-specific
biokineticanddosimetricmodelsforselectedelementsandradionuclides.ThisTask
Group,togetherwiththeTaskGrouponDoseCalculations,haspreparedaseriesof
publications giving dose coefficients (committed equivalent doses and committed
effectivedosesperunitintake)forintakesofradionuclidesbymembersofthepublic
and workers.
Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995b,c) gave age-specific
biokineticmodels formembersofthepublic forintakesbyingestionand inhalation
of 31 elements. For these elements, dose coefficients were calculated for the most
radiologically significant natural or artificial radioisotopes that might be released
into the environment due to various human activities. In Publication 72 (ICRP,
1996), a compilation of age-dependent committed effective doses for members of
the public for intakes by ingestion and inhalation was given for the radionuclides
covered in Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995b,c).
Committed effective doses for the inhalation or ingestion of radionuclides by
workers who are occupationally exposed have been given in Publication 68 (ICRP,
1994b) based on the most recent dosimetric and biokineticmodels for adults. Addi-
tionally, a compilation of dose coefficients for both workers and members of the
public has been issued on a CD-ROM (ICRP, 1999).
Publication 88 (2001) gave dose coefficients for the offspring (embryo, fetus, and
newbornchild)offemalemembersofthepublicandfemaleworkersfollowingacute
or chronic intakes of radionuclides either before or during pregnancy. The radio-
nuclidesconsideredwereselectedisotopesofthe31elementsforwhichage-dependent
biokineticmodelsweregiveninPublications56,67,69,and71.Thereportcoveredthe
doses received in utero and after birth arising from radionuclides transferred across
theplacenta,andthedosereceivedinuterofrommaternaldepositsofradionuclides.
ACD-ROM has been issued (ICRP, 2002a) giving supplementary data.
The present report gives dose coefficients for the infant due to intakes of radio-
nuclides in maternal milk. As in Publication 88 (ICRP, 2001), intakes by female
members of the public and female workers are addressed, considering acute and
chronic intakes by ingestion or inhalation at various times before and during preg-
nancy as well as during the period of breastfeeding. Dose coefficients are given for
the selected isotopes of the 31 elements for which age-dependent biokinetic models
were given in Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995b,c). Dose
coefficients are also given for isotopes of four additional elements: sodium, magne-
sium, phosphorus, and potassium. Relevant human and animal data on elemental
and radionuclide transfer to milk are reviewed. The biokinetic models for adults
given in Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995b,c) for 31 ele-
ments, and in Publication 30 (ICRP, 1979, 1980, 1981) for sodium, magnesium,
phosphorus, and potassium, are adapted to include transfer to milk. Model predic-
tions of fractional transfer of ingested or inhaled activity to milk are discussed in
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the report, and the correspondingdose coefficients forthe infant are compared with
dose coefficients for in utero exposure, as given in Publication 88 (ICRP, 2001).
Illustrative information is also given on doses to the female breast from radionuc-
lides in breast milk, and external doses received by the child from radionuclides re-
tained in the tissues of the mother. For the additional elements considered in this
report, but not in Publication 88 (ICRP, 2001), information is also given on doses
to the embryo and fetus following maternal intakes of radioisotopes during or be-
fore pregnancy.
A CD-ROM is to be issued giving data that will supplement the information in
this report. In addition to the dose coefficients given here, committed equivalent
doses to the various organs and tissues of the offspring will be given. Dose coeffi-
cients will also be given for inhalation of a range of particle sizes for the selected
radionuclides of the elements covered by this report.
The membership of the Task Group on Internal Dosimetry was as follows:
J.W. Stather (Chairman) R.A. Guilmette H. Me´tivier
E. Ansoborlo J.D. Harrison D. Noßke
M.R. Bailey N. Ishigure F. Paquet
A. Bouville R.W. Leggett D.M. Taylor
K.F. Eckerman, as the Chairman of the Task Group on Dose Calculations, is an
(cid:2)ex-officio(cid:1) member of the Task Group on Internal Dosimetry.
The corresponding members were:
A. Birchall W. Kreyling A. Rannou
X.-A. Chen D. Lee P. Roth
F.A. Fry D. Newton T.J. Smith
O. Hoffman M.-L. Perrin D. Whillans
J. Inaba J. Piechowski
The membership of the Task Group on Dose Calculations was as follows:
K.F. Eckerman (Chairman) H. Menzel A.W. Phipps
V. Berkovski D. Noßke B. Siebert
W. Bolch N. Petoussi-Henß M. Zankl
N. Hertel
The corresponding members were:
L. Bertelli R.W. Leggett M. Stabin
T.P. Fell I.A. Likhtarev A. Ulanovsky
J.G. Hunt G. Miller G. Xu
L. Johansson M. Pelliccioni
G.M. Kendall R. Richardson
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The membership of Committee 2 during the period of preparation of this report
was:
(1997–2001)
A. Kaul (Chairman) F.A. Fry A.R. Reddy
A. Bouville J. Inaba M. Roy
B.B. Boecker I.A. Likhtarev J.W. Stather
X. Chen J.L. Lipsztein D.M. Taylor
G. Dietze H. Me´tivier T. Wøhni
K.F. Eckerman H. Paretzke (1997–1998)
(2001–2005)
C. Streffer (Chairman) F.A. Fry H. Paretzke
M. Balonov J. Inaba A.S. Pradhan
B.B. Boecker I.A. Likhtarev J.W. Stather
A. Bouville J.L. Lipsztein D.M. Taylor
G. Dietze H.-G. Menzel Y. Zhou
K.F. Eckerman H. Me´tivier
7