Lung cancer risk and effective dose coefficients for radon: UNSCEAR review and ICRP conclusions.

The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has provided a detailed and authoritative update of its reviews of the epidemiology and dosimetry of radon and progeny. Lifetime risk of lung cancer calculated using data for several miner cohorts were 2.4-7.5 × 10-4per working level month (WLM) of radon-222 progeny exposure for a mixed male/female population and 3.0-9.6 × 10-4per WLM for a male population. Dosimetric models gave mean values of effective dose coefficients from radon-222 progeny of 12 mSv per WLM for mines, 16 mSv per WLM for indoor workplaces and 11 mSv per WLM for homes. The lifetime risk coefficient used by the International Commission on Radiological Protection (ICRP) is 5 × 10-4per WLM and it has recently recommended an effective dose coefficient for radon-222 and progeny of 3 mSv per mJ h m-3(about 10 mSv per WLM) for most circumstances of exposure. The ICRP risk and dose coefficients are supported by the UNSCEAR review and provide a clear and firm basis for current international advice and standards for protection from radon. Notwithstanding this evidence and the ICRP advice, UNSCEAR will continue to use a lower value of effective dose coefficient of 5.7 mSv per WLM for assessments of population exposures.

The use of dose quantities in radiological protection: ICRP publication 147 Ann ICRP 50(1) 2021.

The International Commission on Radiological Protection has recently published a report (ICRP Publication 147;Ann. ICRP50, 2021) on the use of dose quantities in radiological protection, under the same authorship as this Memorandum. Here, we present a brief summary of the main elements of the report. ICRP Publication 147 consolidates and clarifies the explanations provided in the 2007 ICRP Recommendations (Publication 103) but reaches conclusions that go beyond those presented in Publication 103. Further guidance is provided on the scientific basis for the control of radiation risks using dose quantities in occupational, public and medical applications. It is emphasised that best estimates of risk to individuals will use organ/tissue absorbed doses, appropriate relative biological effectiveness factors and dose-risk models for specific health effects. However, bearing in mind uncertainties including those associated with risk projection to low doses or low dose rates, it is concluded that in the context of radiological protection, effective dose may be considered as an approximate indicator of possible risk of stochastic health effects following low-level exposure to ionising radiation. In this respect, it should also be recognised that lifetime cancer risks vary with age at exposure, sex and population group. The ICRP report also concludes that equivalent dose is not needed as a protection quantity. Dose limits for the avoidance of tissue reactions for the skin, hands and feet, and lens of the eye will be more appropriately set in terms of absorbed dose rather than equivalent dose.

Assessing the reliability of dose coefficients for exposure to radioiodine by members of the public, accounting for dosimetric and risk model uncertainties.

Assessments of risk to a specific population group resulting from internal exposure to a particular radionuclide can be used to assess the reliability of the appropriate International Commission on Radiological Protection (ICRP) dose coefficients used as a radiation protection device for the specified exposure pathway. An estimate of the uncertainty on the associated risk is important for informing judgments on reliability; a derived uncertainty factor, UF, is an estimate of the 95% probable geometric difference between the best risk estimate and the nominal risk and is a useful tool for making this assessment. This paper describes the application of parameter uncertainty analysis to quantify uncertainties resulting from internal exposures to radioiodine by members of the public, specifically 1, 10 and 20-year old females from the population of England and Wales. Best estimates of thyroid cancer incidence risk (lifetime attributable risk) are calculated for ingestion or inhalation of 129I and 131I, accounting for uncertainties in biokinetic model and cancer risk model parameter values. These estimates are compared with the equivalent ICRP derived nominal age-, sex- and population-averaged estimates of excess thyroid cancer incidence to obtain UFs. Derived UF values for ingestion or inhalation of 131I for 1 year, 10-year and 20-year olds are around 28, 12 and 6, respectively, when compared with ICRP Publication 103 nominal values, and 9, 7 and 14, respectively, when compared with ICRP Publication 60 values. Broadly similar results were obtained for 129I. The uncertainties on risk estimates are largely determined by uncertainties on risk model parameters rather than uncertainties on biokinetic model parameters. An examination of the sensitivity of the results to the risk models and populations used in the calculations show variations in the central estimates of risk of a factor of around 2-3. It is assumed that the direct proportionality of excess thyroid cancer risk and dose observed at low to moderate acute doses and incorporated in the risk models also applies to very small doses received at very low dose rates; the uncertainty in this assumption is considerable, but largely unquantifiable. The UF values illustrate the need for an informed approach to the use of ICRP dose and risk coefficients.

Strontium biokinetic model for the pregnant woman and fetus: application to Techa River studies.

A biokinetic model for strontium (Sr) for the pregnant woman and fetus (Sr-PWF model) has been developed for use in the quantification of doses from internal radiation exposures following maternal ingestion of Sr radioisotopes before or during pregnancy. The model relates in particular to the population of the Techa River villages exposed to significant amounts of ingested Sr radioisotopes as a result of releases of liquid radioactive wastes from the Mayak plutonium production facility (Russia) in the early 1950s. The biokinetic model for Sr metabolism in the pregnant woman was based on a biokinetic model for the adult female modified to account for changes in mineral metabolism during pregnancy. The model for non-pregnant females of all ages was developed earlier with the use of extensive data on (90)Sr-body measurements in the Techa Riverside residents. To determine changes in model parameter values to take account of changing mineral metabolism during pregnancy, data from longitudinal studies of calcium homeostasis during human pregnancy were analysed and applied. Exchanges between maternal and fetal circulations and retention in fetal skeleton and soft tissues were modelled as adaptations of previously published models, taking account of data on Sr and calcium (Ca) metabolism obtained in Russia (Southern Urals and Moscow) relating to dietary calcium intakes, calcium contents in maternal and fetal skeletons and strontium transfer to the fetus. The model was validated using independent data on (90)Sr in the fetal skeleton from global fallout as well as unique data on (90)Sr-body burden in mothers and their still-born children for Techa River residents. While the Sr-PWF model has been developed specifically for ingestion of Sr isotopes by Techa River residents, it is also more widely applicable to maternal ingestion of Sr radioisotopes at different times before and during pregnancy and different ages of pregnant women in a general population.

Strontium biokinetic model for the lactating woman and transfer to breast milk: application to Techa River studies.

This paper presents a biokinetic model for strontium metabolism in the lactating woman and transfer to breast milk for members of Techa River communities exposed as a result of discharges of liquid radioactive wastes from the Mayak plutonium production facility (Russia) in the early 1950s. This model was based on that developed for the International Commission for Radiological Protection with modifications to account for population specific features of breastfeeding and maternal bone mineral metabolism. The model is based on a biokinetic model for the adult female with allowances made for changes in mineral metabolism during periods of exclusive and partial breast-feeding. The model for females of all ages was developed earlier from extensive data on (90)Sr-body measurements for Techa Riverside residents. Measurements of (90)Sr concentrations in the maternal skeleton and breast milk obtained in the1960s during monitoring of global fallout in the Southern Urals region were used for evaluation of strontium transfer to breast and breast milk. The model was validated with independent data from studies of global fallout in Canada and measurements of (90)Sr body-burden in women living in the Techa River villages who were breastfeeding during maximum (90)Sr-dietary intakes. The model will be used in evaluations of the intake of strontium radioisotopes in breast milk by children born in Techa River villages during the radioactive releases and quantification of (90)Sr retention in the maternal skeleton.

Solid cancer incidence other than lung, liver and bone in Mayak workers: 1948-2004.

BACKGROUND: Cancer incidence in the Mayak Production Association (PA) cohort was analysed to investigate for the first time whether external gamma-ray and internal plutonium exposure are associated with raised incidence of solid cancers other than lung, liver and bone (other solid cancers). METHODS: The cohort includes 22,366 workers of both sexes who were first employed between 1948 and 1982. A total of 1447 cases of other solid cancers were registered in the follow-up period until 2004. The Poisson regression was used to estimate the excess relative risk (ERR) per unit of cumulative exposure to plutonium and external gamma-ray. RESULTS: A weak association was found between cumulative exposure to external gamma-ray and the incidence of other solid cancers (ERR/Gy=0.07; 95% confidence intervals (CIs): 0.01-0.15), but this association lost its significance after adjusting for internal plutonium exposure. There was no indication of any association with plutonium exposure for other solid cancers. Among 16 individual cancer sites, there was a statistically significant association with external exposure for lip cancer (ERR/Gy=1.74; 95% CI: 0.37; 6.71) and with plutonium exposure for pancreatic cancer (ERR/Gy=1.58; 95% CI; 0.17; 4.77). CONCLUSION: This study of Mayak workers does not provide evidence of an increased risk of other solid cancers. The observed increase in the risk of cancer of the lip and pancreas should be treated with caution because of the limited amount of relevant data and because the observations may be simply due to chance.

Assessment of the selection process for myocutaneous flap repair and surgical complications in pelvic exenteration surgery.

BACKGROUND: This study aimed to explore and quantify the selection process to guide the decision on closure type (myocutaneous flap repair (MFR) or primary closure) for people undergoing pelvic exenteration. METHODS: This was a retrospective analysis of a prospectively maintained database with review of hospital records for verification and capture of missing data. Associations between four risk factors (previous radiotherapy, previous abdominoperineal resection, need for total exenteration, need for sacrectomy) were assessed individually and collectively as predictors of closure type and wound complications. RESULTS: A total of 203 pelvic exenteration procedures were reviewed (75 primary and 122 recurrent cancers). Thirty-nine patients (19·2 per cent) had MFR and 164 (80·8 per cent) primary closure. Patients who had MFR were significantly more likely to exhibit each risk factor, confirming the selective decision process. MFR had higher rates of complications across all four risk factors, individually and combined. In the primary closure group, there was a significant correlation between the number of risk factors and the proportion of patients with a complication (r = 0·25, P = 0·008). In contrast, no such relationship was found for the MFR group (r = 0·01, P = 0·973). Among patients who had any complication, the primary closure group had significantly lower rates of any wound dehiscence (15 of 64 versus 17 of 28; P < 0·001) and total infection (16 of 64 versus 14 of 28; P = 0·019) compared with the MFR group. CONCLUSION: Rates of wound and septic complications after pelvic exenteration were low in patients with fewer than two risk factors who had a primary closure. MFR had significantly higher complication rates, and should be reserved for patients with two or more risk factors or extensive skin involvement.

Quantifying postdischarge unmet supportive care needs of people with colorectal cancer: a clinical audit.

AIM: There are limited data concerning the unmet needs experienced by patients with colorectal cancer. The aim of this study was to identify unmet supportive care needs of people with colorectal cancer following discharge from hospital. METHOD: Health service utilization was used as a measure of expressed unmet need. A retrospective case note review was conducted of 521 patients surgically treated for colorectal cancer at Royal Prince Alfred Hospital, Sydney, between 1 January 2004 and 31 December 2007. Case notes maintained by a cancer nurse specialist were reviewed to identify postdischarge occasions-of-service where unmet need was expressed. Logistic regression was conducted to investigate predictors of unmet need. RESULTS: Of 521 patients, 219 (42%) patients had unmet supportive care needs, of which 50% of all needs was found in the physical domain. Twenty-six per cent of unmet needs was expressed within the first week following discharge from hospital after cancer surgery; however, 21% persisted after 6 months. Multivariate analysis indentified that in this cohort, younger age predicted the expression of an unmet need (AOR, 0.97; 95% CI, 0.96-0.99). People with rectal cancer remained significantly more likely to require more than one contact with the nurse to satisfy a need (AOR, 2.80; 95% CI, 1.60-5.01) and to report a physical need (AOR, 3.56; 95% CI, 2.03-6.27). CONCLUSION: This study has shown that auditing the interactions of a cancer nurse with patients can provide information about unmet supportive care needs, which can be used to develop relevant supportive care services or interventions for people with colorectal cancer.

What is important in cancer care coordination? A qualitative investigation.

Although it is widely recognised that better coordination of cancer care holds considerable potential to improve patients' experience of care and their outcomes, there is no agreed definition of the term 'care coordination' or consensus as to what it entails. An explorative descriptive qualitative study was undertaken to explore the views and experiences of key stakeholders to identify the key components of cancer care coordination. We conducted semi-structured individual and focus groups interviews with patients (n= 20) who have been treated for any cancer and carers (n= 4) as well as clinicians (n= 29) involved in cancer care, using open-ended questions. Data were collected until saturation of concepts was reached. A phenomenological approach based on grounded theory was used to explore the participants' experiences and views. Seven key components were identified: organisation of patient care, access to and navigation through the healthcare system, the allocation of a 'key contact' person, effective communication and cooperation among the multidisciplinary team and other health service providers, delivery of services in a complementary and timely manner, sufficient and timely information to the patient and needs assessment. The components of cancer care coordination identified provide an empirical basis for the development of metrics and interventions to improve this aspect of cancer care.

Risks from ionising radiation: an HPA viewpoint paper for Safegrounds.

Safegrounds is a forum for developing and disseminating good practice guidance on the management of radioactively contaminated land on nuclear and defence sites in the UK. This review has been provided to Safegrounds as a summary of the basis for current radiation risk estimates and the International Commission on Radiological Protection (ICRP) protection system, in a form that will be accessible to a wide range of stakeholders. Safegrounds has also received viewpoint papers from other members who contend that the ICRP methodology results in substantial underestimates of risk, particularly for internal emitters. There is an extensive literature on the risks of radiation exposure, regularly reviewed by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and other expert groups. These data provide a sound basis for the system of protection recommended by ICRP. The available epidemiological and experimental evidence supports the application of cancer risk estimates derived for acute, high dose, external exposures to low dose exposures to external and internal sources. In the context of radioactively contaminated land on nuclear and defence sites, the national standards for the cleaning up of land and for waste disposal correspond to very low doses, two orders of magnitude less than average annual doses in the UK from natural background radiation (10-20  µSv compared with 2-3 mSv). Risks at such very low doses can only be estimated on the basis of observations after exposure of population groups at much higher doses. The estimated risks at these very low doses, while uncertain, are as likely to be overestimates as underestimates.

ICRP recommendations on radon.

The International Commission on Radiological Protection (ICRP) publishes guidance on protection from radon in homes and workplaces, and dose coefficients for use in assessments of exposure for protection purposes. ICRP Publication 126 recommends an upper reference level for exposures in homes and workplaces of 300 Bq m-3. In general, protection can be optimised using measurements of air concentrations directly, without considering radiation doses. However, dose estimates are required for workers when radon is considered as an occupational exposure (e.g. in mines), and for higher exposures in other workplaces (e.g. offices) when the reference level is exceeded persistently. ICRP Publication 137 recommends a dose coefficient of 3 mSv per mJ h m-3 (approximately 10 mSv per working level month) for most circumstances of exposure in workplaces, equivalent to 6.7 nSv per Bq h m-3 using an equilibrium factor of 0.4. Using this dose coefficient, annual exposure of workers to 300 Bq m-3 corresponds to 4 mSv. For comparison, using the same coefficient for exposures in homes, 300 Bq m-3 corresponds to 14 mSv. If circumstances of occupational exposure warrant more detailed consideration and reliable alternative data are available, site-specific doses can be assessed using methodology provided in ICRP Publication 137.

[Pattern recognition in the differential diagnosis of salivary lymphoepithelial lesions]. / Mustererkennung zur Differenzialdiagnose lymphoepithelialer Läsionen der Speicheldrüsen.

The prototype of a salivary lymphoepithelial lesion is the autoimmune disease Sjögren's syndrome with the characteristic lymphoepithelial duct lesions (LEL). The distinction of Sjögren's syndrome from cases with initial transformation into associated marginal zone B-cell lymphoma (MALT type) can be very challenging, whereby the presence of small "halos" can lead to over-diagnosis. The HIV-associated cystic lymphoepithelial lesion can be histologically almost identical to Sjögren's syndrome and often needs clinical correlation. The sporadic lymphoepithelial cyst of the parotid gland is a frequent finding and has no clinical consequence; however, this entity needs to be identified and distinguished from the above-mentioned entities. The most frequent diagnosis in resected submandibular glands is chronic-fibrosing sialadenitis, so-called Küttner's tumour. Altogether, there is a wide spectrum of lymphoepithelial interaction in the area of salivary glands, including biphasic lymphoepithelial tumours with an obligate lymphoid component, epithelial tumours with facultative tumour-associated lymphoid proliferation, and different processes of intraparotid lymph nodes. The immunohistological reaction for pan-keratin can be very helpful for a thorough pattern analysis of the different lymphoepithelial lesions. The relative frequency of the lesions in different salivary glands can also be diagnostically helpful.

ICRP Publication 141: Occupational Intakes of Radionuclides: Part 4.

The 2007 Recommendations (ICRP, 2007) introduced changes that affect the calculation of effective dose, and implied a revision of the dose coefficients for internal exposure, published previously in the Publication 30 series (ICRP, 1979a,b, 1980a, 1981, 1988) and Publication 68 (ICRP, 1994b). In addition, new data are now available that support an update of the radionuclide-specific information given in Publications 54 and 78 (ICRP, 1989a, 1997) for the design of monitoring programmes and retrospective assessment of occupational internal doses. Provision of new biokinetic models, dose coefficients, monitoring methods, and bioassay data was performed by Committee 2 and its task groups. A new series, the Occupational Intakes of Radionuclides (OIR) series, will replace the Publication 30 series and Publications 54, 68, and 78. OIR Part 1 (ICRP, 2015) describes the assessment of internal occupational exposure to radionuclides, biokinetic and dosimetric models, methods of individual and workplace monitoring, and general aspects of retrospective dose assessment. OIR Part 2 (ICRP, 2016), OIR Part 3 (ICRP, 2017), this current publication, and the final publication in the OIR series (OIR Part 5) provide data on individual elements and their radioisotopes, including information on chemical forms encountered in the workplace; a list of principal radioisotopes and their physical half-lives and decay modes; the parameter values of the reference biokinetic models; and data on monitoring techniques for the radioisotopes most commonly encountered in workplaces. Reviews of data on inhalation, ingestion, and systemic biokinetics are also provided for most of the elements. Dosimetric data provided in the printed publications of the OIR series include tables of committed effective dose per intake (Sv per Bq intake) for inhalation and ingestion, tables of committed effective dose per content (Sv per Bq measurement) for inhalation, and graphs of retention and excretion data per Bq intake for inhalation. These data are provided for all absorption types and for the most common isotope(s) of each element. The online electronic files that accompany the OIR series of publications contains a comprehensive set of committed effective and equivalent dose coefficients, committed effective dose per content functions, and reference bioassay functions. Data are provided for inhalation, ingestion, and direct input to blood. This fourth publication in the OIR series provides the above data for the following elements: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), actinium (Ac), protactinium (Pa), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), and fermium (Fm).

Immunohistochemical study of fibroblasts and mast cells in chronic submandibular sialadenitis.

AIM: To further our understanding of the processes involved in fibrosis that occurs in chronic submandibular sialadenitis by investigating the distribution of myofibroblasts, CD34-positive fibroblasts and tryptase-containing mast cells. MATERIALS AND METHODS: Thirty specimens of chronic submandibular sialadenitis with varying degrees of fibrosis and five normal submandibular glands were examined immunohistochemically for the presence of CD34, alpha-smooth-muscle-actin, desmin and tryptase. RESULTS: Myofibroblasts were not demonstrated by the techniques for alpha-smooth-muscle-actin or desmin. CD34-positive fibroblasts were found around normal and moderately atrophic acini, but were not found around extremely atrophic acini and duct-like structures or in periductal and interlobular fibrous tissue. Tryptase-containing mast cells were found around vessels in normal submandibular glands. They were found in increased numbers in chronic submandibular sialadenitis, particularly in glands with widespread fibrosis, in which they were found in the fibrous tissue, and in which the increase was statistically significant. CONCLUSIONS: The results of this investigation suggest that tryptase-containing mast cells are likely to be involved in the fibrosis of chronic submandibular sialadenitis, but myofibroblasts and CD34-positive fibroblasts are not.

The mandate and work of ICRP Committee 2 on doses from radiation exposure.

The practical implementation of the International Commission on Radiological Protection's (ICRP) system of radiological protection requires the availability of appropriate methodology and data. Over many years, ICRP Committee 2 has provided sets of dose coefficients to allow users to evaluate equivalent and effective doses for radiation exposures of workers and members of the public. The methodology being applied in the calculation of doses is state-of-the-art in terms of the biokinetic models used to describe the behaviour of inhaled and ingested radionuclides, and the dosimetric models used to model radiation transport for external and internal exposures. This overview provides an outline of recent work and future plans, including publications on dose coefficients for adults, children, and in-utero exposures, with new dosimetric phantoms in each case. For the first time, ICRP will publish dose coefficients for intakes of radon isotopes calculated using dosimetric models. Committee 2 is also working with Committee 3 on dose coefficients for radiopharmaceuticals, and leading a cross-committee initiative to provide advice on the use of effective dose. The remit of Committee 2 has now been widened to include all data requirements for the assessment of doses to humans and non-human biota.

The ICRP protection quantities, equivalent and effective dose: their basis and application.

Equivalent and effective dose are protection quantities defined by the The International Commission on Radiological Protection (ICRP). They are frequently referred to simply as dose and may be misused. They provide a method for the summation of doses received from external sources and from intakes of radionuclides for comparison with dose limits and constraints, set to limit the risk of cancer and hereditary effects. For the assessment of internal doses, ICRP provides dose coefficients (Sv Bq(-1)) for the ingestion or inhalation of radionuclides by workers and members of the public, including children. Dose coefficients have also been calculated for in utero exposures following maternal intakes and for the transfer of radionuclides in breast milk. In each case, values are given of committed equivalent doses to organs and tissues and committed effective dose. Their calculation involves the use of defined biokinetic and dosimetric models, including the use of reference phantoms representing the human body. Radiation weighting factors are used as a simple representation of the different effectiveness of different radiations in causing stochastic effects at low doses. A single set of tissue weighting factors is used to take account of the contribution of individual organs and tissues to overall detriment from cancer and hereditary effects, despite age- and gender-related differences in estimates of risk and contributions to risk. The results are quantities that are not individual specific but are reference values for protection purposes, relating to doses to phantoms. The ICRP protection quantities are not intended for detailed assessments of dose and risk to individuals. They should not be used in epidemiological analyses or the assessment of the possibility of occurrence and severity of tissue reactions (deterministic effects) at higher doses. Dose coefficients are published as reference values and as such have no associated uncertainty. Assessments of uncertainties may be appropriate in specific analyses of doses and risks and in epidemiological studies.

In utero and postnatal haemopoietic tissue doses resulting from maternal ingestion of strontium isotopes from the Techa River.

Reliable estimates of tissue doses to individuals exposed as a result of radioactive releases to the Techa River are essential prerequisites for epidemiological analyses. This paper describes progress made in collaborative studies, sponsored by the European Union, between the Urals Research Center for Radiation Medicine and the UK Health Protection Agency to provide dose estimates to Techa River populations following in utero exposures and infant exposures resulting from breast-feeding. Studies have concentrated on the assessment of internal doses from 90Sr as the main contributor to internal doses to the Techa River populations.

Dose coefficients calculated using the new ICRP model for the human alimentary tract.

Publication 100 of the International Commission on Radiological Protection (ICRP) provides a Human Alimentary Tract Model (HATM) to replace the gastrointestinal (GI) model described in Publication 30. The HATM will be used for future calculations of dose coefficients and bioassay predictions, first in a series of publications on occupational intakes of radionuclides, and subsequently in revision of dose coefficients for public exposures. This paper compares dose coefficients calculated using the new model with current values calculated using the GI model for a range of radionuclides. Colon doses are lower using the HATM in all cases considered, in some cases by significant factors. Stomach doses tend to be lower, but are in some cases higher under HATM. The extent to which these changes in doses to gut tissues impacts upon the effective dose varies among nuclides, but there is a tendency for lower effective doses. Special-case applications of the HATM are also described, considering retention on teeth or in the walls of the small intestine. Although the effect of such retention on the regional tissue dose can be large, the effective dose is not greatly changed.

Review of standards of protection for pregnant workers and their offspring.

The recommendations of the International Commission on Radiological Protection and the IAEA Basic Safety Standards (BSS) make clear that the embryo and fetus should be regarded as a member of the public when considering the protection of female workers who are or may be pregnant. The BSS note that the embryo and fetus should be 'afforded the same broad level of protection as required for members of the public'. Similar guidance is included in national legislation in a number of countries. On the basis of a review of such guidance, it was concluded that although the recommendations provided in the BSS are in general agreement with the international consensus on approaches to the protection of pregnant workers and their offspring, more specific supporting guidance is needed. The IAEA is preparing a technical document that extends and clarifies previous advice and considers the practical application of the advice for workers in different types of workplace, for which important potential routes of exposure for the pregnant worker have been identified. This action is being carried out under the framework of the International Action Plan for Occupational Radiation Protection.