Paternal preconceptional radiation exposure in the nuclear industry and leukaemia and non-Hodgkin's lymphoma in young people in Scotland.

OBJECTIVE--To determine if a relation exists between paternal exposure to relatively high levels of radiation in the Scottish nuclear industry and the risk of leukaemia and non-Hodgkin''s lymphoma is subsequently conceived children. DESIGN--Matched case-control study with three controls for each case. SETTING--The whole of Scotland. SUBJECTS--The fathers of 1024 children with leukaemia and 237 children with non-Hodgkin''s lymphoma diagnosed in Scotland below the age of 25 among those born in Scotland since nuclear operations began (in 1958) and the fathers of 3783 randomly chosen controls. The fathers of 80 children with leukaemia and 16 with non-Hodgkin''s lymphoma in north Cumbria were also covered since some workers at one Scottish nuclear site live over the border in that area. Details of all fathers were then matched against records of the nuclear industry. MAIN OUTCOME MEASURES--Paternal preconceptional radiation exposures, particularly relatively high levels, both lifetime and in the six and three months before conception. RESULTS--No significant excess was observed in any subgroup and there was no significant trend: fathers of three controls but no cases were exposed to lifetime preconceptional levels of 100 mSv or greater (Fisher''s exact p value 0.84). In the six months before conception, fathers of two cases and three controls received 10 mSv or more, odds ratio 2.3 (95% confidence interval 0.31 to 17.24). In the three months before conception the fathers of one case and two controls received 5 mSv or more, odds ratio 1.7 (0.10 to 30.76). The results for leukaemia and non-Hodgkin''s lymphoma combined were similar. CONCLUSIONS--No significant excess of leukaemia or of leukaemia and non-Hodgkin''s lymphoma was found at any radiation level in any preconceptional period.     

Results of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria.

OBJECTIVE--To examine whether the observed excess of childhood leukaemia and lymphoma near the Sellafield nuclear plant is associated with established risk factors or with factors related to the plant. DESIGN--A case-control study. SETTING--West Cumbria health district. SUBJECTS--52 Cases of leukaemia, 22 of non-Hodgkin''s lymphoma, and 23 of Hodgkin''s disease occurring in people born in the area and diagnosed there in 1950-85 under the age of 25 and 1001 controls matched for sex and date of birth taken from the same birth registers as the cases. MAIN OUTCOME MEASURES--Antenatal abdominal x ray examinations, viral infections, habit factors, proximity to and employment characteristics of parents at Sellafield. RESULTS--Expected associations with prenatal exposure to x rays were found, but little information was available on viral illnesses. Relative risks for leukaemia and non-Hodgkin''s lymphoma were higher in children born near Sellafield and in children of fathers employed at the plant, particularly those with high radiation dose recordings before their child''s conception. For example, the relative risks compared with area controls were 0.17 (95% confidence interval 0.05 to 0.53) for being born further than 5 km from Sellafield 2.44 (1.04 to 5.71) for children of fathers employed at Sellafield at their conception, and 6.42 (1.57 to 26.3) for children of fathers receiving a total preconceptual ionising radiation dose of 100 mSv or more. Other factors, including exposure to x rays, maternal age, employment elsewhere, eating seafood, and playing on the beach did not explain these relationships. Focusing on Seascale, where the excess incidence has predominantly been reported, showed for the four out of five cases of leukaemia and one case of non-Hodgkin''s lymphoma whose fathers were employed at Sellafield and for whom dose information was obtained that the fathers of each case had higher radiation doses before their child''s conception than all their matched control fathers; the father of the other Seascale case (non-Hodgkin''s lymphoma) was not employed at the plant. These results seem to explain statistically the geographical association. For Hodgkin''s disease neither geographical nor employment associations with Sellafield were found. CONCLUSIONS--The raised incidence of leukaemia, particularly, and non-Hodgkin''s lymphoma among children near Sellafield was associated with paternal employment and recorded external dose of whole body penetrating radiation during work at the plant before conception. The association can explain statistically the observed geographical excess. This result suggests an effect of ionising radiation on fathers that may be leukaemogenic in their offspring, though other, less likely, explanations are possible. There are important potential implications for radiobiology and for protection of radiation workers and their children.     

Paternal radiation exposure and leukaemia in offspring: the Ontario case-control study.

OBJECTIVES--To test the hypothesis that there is an association between childhood leukaemia and the occupational exposure of fathers to ionising radiation before a child''s conception. DESIGN--Case-control study with eight matched controls per case. SETTING--Regions of Ontario, Canada, with an operating nuclear facility. SUBJECTS--Cases were children (age 0-14) who died from or were diagnosed as having leukaemia from 1950 to 1988 and were born to mothers living in the vicinity of an operating nuclear facility. Controls were identified from birth certificates, matched by date of birth and residence at birth. There were 112 cases and 890 controls. MAIN OUTCOME MEASURES--Paternal radiation exposure was determined by a record linkage to the Canadian National Dose Registry. RESULTS--Six fathers of cases and 53 fathers of controls had had a total whole body dose > 0.0 mSv before the child''s conception, resulting in an odds ratio of 0.87 (95% confidence interval 0.32 to 2.34). There was no evidence of an increased leukaemia risk in relation to any exposure period (lifetime or six months or three months before conception) or exposure type (total whole body dose, external whole body dose, or tritium dose), except for radon exposure to uranium miners, which had a large odds ratio that was not significantly different from the null value. CONCLUSIONS--The findings of this study in Ontario did not support the hypothesis that childhood leukaemia is associated with the occupational exposure of fathers to ionising radiation before the child''s conception.     

Geographical distribution of preconceptional radiation doses to fathers employed at the Sellafield nuclear installation,West Cumbria.

OBJECTIVE--To examine whether the geographical distribution of births associated with preconceptional exposure of fathers to radiation at the Sellafield nuclear installation is consistent with the suggestion that this exposure explains the excess of childhood lymphoid malignancy in the adjacent village of Seascale. DESIGN--Retrospective birth cohort study. SETTING--Cumbria, West Cumbria health district, and Seascale civil parish. SUBJECTS--The 10,363 children born in Cumbria during 1950-89 to fathers employed at Sellafield. MAIN OUTCOME MEASURES--The doses of external whole body ionising radiation received by fathers at Sellafield in the total time and in the six months before conception of their children; the proportions of the collective doses associated with Seascale and the rest of West Cumbria. RESULTS--9256 children were born to fathers who had been exposed to radiation before the child''s conception. Of these, 7318 had fathers who were exposed in the six months before conception. Overall 7% (38 person-Sv) of the collective total preconceptional dose and 7% (3 person-Sv) of the collective dose for the six months before conception were associated with children born in Seascale. Of all the children whose fathers worked at Sellafield, 842 (8%) were born in Seascale. The mean individual doses before conception were consistently lower in Seascale than in the rest of West Cumbria. CONCLUSIONS--The distribution of the paternal preconceptional radiation dose is statistically incompatible with this exposure providing a causal explanation for the cluster of childhood leukaemias in Seascale.     

Ionising radiations from nuclear establishments and childhood leukaemias--an enigma

The Gardner report, recently published in the UK, showing a correlation between incidence of childhood leukaemia and paternal exposure to ionising radiations (amongst fathers working in nuclear power plants) has added a new element to debates about both the risk factors in nuclear power plants and the relationships between ionising radiations and leukaemogenesis. The epidemiologic and genetic evidence concerning leukaemias is reviewed here and it is concluded that the leukaemogenic agent, whose existence is indicated in the Gardner report, is unlikely to be paternal radiation dose per se but rather exposure to another factor that is correlated with parternal radiation dose received.     

Mortality of employees of the United Kingdom Atomic Energy Authority, 1946-1979.

An analysis was conducted of 3373 deaths among 39 546 people employed by the United Kingdom Atomic Energy Authority between 1946 and 1979, the population having been followed up for an average of 16 years. Overall the death rates were below those prevailing in England and Wales but consistent with those expected in a normal workforce. At ages 15-74 years the standardised mortality ratios (SMRs) were 74 for deaths from all causes and 79 for deaths from all cancers. Mortality from only four causes was above the national average--namely, testicular cancer (SMR 153; 10 deaths), leukaemia (SMR 123; 35 deaths), thyroid cancer (SMR 122; three deaths), non-Hodgkin''s lymphoma (SMR 107; 20 deaths)--but in none was the increase significant at the 5% level. Half of the authority''s employees were recorded as having been monitored for exposure to radiation, their collective recorded exposure being 660 Sv (65 954 rem). Among these prostatic cancer was the only condition with a clearly increased mortality in relation to exposure. Of the 19 men who had a radiation record and died from prostatic cancer at ages 15-74 years, nine had been monitored for several different sources of exposure to radiation. The standardised mortality ratios were 889 (six deaths) in employees monitored for contamination by tritium, 254 (nine deaths) in those monitored for contamination by other radionuclides, and 385 (nine deaths) in those with dosimeter readings totalling more than 50 mSv (5 rem); but the same nine subjects tended to account for each of these significantly raised ratios. Because multiple exposures were common and other relevant information was not available the reason for the increased mortality from prostatic cancer in this population could not be determined and requires further investigation. Excess mortality rates of 2.2 and 12.5 deaths per million person years per 10 mSv (1 rem) were estimated for leukaemia and all cancers, respectively. The confidence limits around these estimates were wide, included zero, and made it unlikely that the International Commission on Radiological Protection''s cancer risk coefficients were underestimated by more than 15-fold. Thus despite this being the largest British workforce whose mortality has been reported in relation to low level ionising radiation exposure, even larger populations will need to be followed up over longer periods before narrower ranges of risk estimates can be derived.     

Trends in childhood leukaemia in the Nordic countries in relation to fallout from atmospheric nuclear weapons testing.

OBJECTIVE--To obtain further information about the risks of childhood leukaemia after exposure to ionising radiation at low doses and low dose rates before or after birth or to the father''s testes shortly before conception. DESIGN--Observational study of trends in incidence of childhood leukaemia in relation to estimated radiation exposures due to fallout from atmospheric nuclear weapons testing during the 1950s and 1960s. SETTING--Nordic countries. SUBJECTS--Children aged under 15 years. MAIN OUTCOME MEASURES--Incidence rates of leukaemia by age at diagnosis, sex, country, and calendar year of diagnosis or year of birth; exposure category; relation between leukaemia and exposure for children aged 0-14 and 0-4 separately. RESULTS--During the high fallout period the average estimated dose equivalent to the fetal red bone marrow was around 140 mu Sv and the average annual testicular dose 140 mu Sv. There was little evidence of increased incidence of leukaemia among children born in these years. Doses to the red bone marrow of a child after birth were higher, and during the high exposure period children would have been subjected to an additional dose equivalent of around 1500 mu Sv, similar to doses received by children in several parts of central and eastern Europe owing to the Chernobyl accident and about 50% greater than the annual dose equivalent to the red bone marrow of a child from natural radiation. leukaemia incidence and red marrow dose was not related overall, but rates of leukaemia in the high exposure period were slightly higher than in the surrounding medium exposure period (relative risk for ages 0-14: 1.07, 95% confidence interval 1.00 to 1.14; for ages 0-4: 1.11, 1.00 to 1.24). CONCLUSIONS--Current predicted risks of childhood leukaemia after exposure to radiation are not greatly underestimated for low dose rate exposures.     

Methods and basic data of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria.

OBJECTIVE--To examine whether the observed excess of childhood leukaemia and lymphoma near the Sellafield nuclear plant is associated with established risk factors or with factors related to the plant. DESIGN--A case-control study. SETTING--West Cumbria health district. SUBJECTS--52 Cases of leukaemia, 22 of non-Hodgkin''s lymphoma, and 23 of Hodgkin''s disease occurring in people born in the area and diagnosed there in 1950-85 under the age of 25 and 1001 controls matched for sex and date of birth taken from the same birth registers as the cases. MAIN OUTCOME MEASURES--Antenatal abdominal x ray examinations, viral infections, habit factors, proximity to and employment characteristics of parents at Sellafield. RESULTS--Ascertainment of cases through multiple sources was as complete as possible, and the diagnosis was established for nearly all cases from hospital records and by independent pathological review when suitable material (60% (58) of cases) was available. Identification and tracing of the parents of cases and controls enabled questionnaires to be forwarded to 730 (66%), and 467 (64%) of the questionnaires were returned completed. Obstetric records were located for 481 (44%) of the relevant births, more frequently in recent years. Linkage of study subjects to the Sellafield workforce file enabled dates of employment and records on external doses of whole body ionising radiation to be obtained. Concordance of information from duplicate sources (when available) was reasonably high with no indications of bias. CONCLUSION--Overall the collected data were sufficiently reliable for detailed analysis and careful interpretation.     

Epipodophyllotoxins,alkylating agents,and radiation and risk of secondary leukaemia after childhood cancer.

OBJECTIVE--To investigate the incidence and aetiology of secondary leukaemia after childhood cancer in Britain. DESIGN--Cohort study and a case-control study. SETTING--Britain and population based National Register of Childhood Tumours. SUBJECTS--Cohort of 16,422 one year survivors of childhood cancer diagnosed in Britain between 1962 and 1983, among whom 22 secondary leukaemias were observed. A case-control study of 26 secondary leukaemias observed among survivors of childhood cancer diagnosed in Britain between 1940 and 1983; 96 controls were selected matched for sex, type of first cancer, age at first cancer, and interval to diagnosis of secondary leukaemia. MAIN OUTCOME MEASURES--Dose of radiation averaged over patients'' active bone marrow and total accumulated dose of epipodophyllotoxins, alkylating agents, vinca alkaloids, antimetabolites, and antibiotics (mg/m2) given for the original cancer. RESULTS--Cumulative risk of secondary leukaemia within the cohort did not exceed 0.5% over the initial five years beyond one year survival, except that after non-Hodgkin''s lymphomas 1.4% of patients developed secondary leukaemia. Corresponding figure for patients treated for non-Hodgkin''s lymphomas in the early 1980s was 4%. The relative risk of secondary leukaemia increased significantly with exposure to epipodophyllotoxins and dose of radiation averaged over patients'' active bone marrow. Ten patients developed leukaemia after having an epipodophyllotoxin-teniposide in nine cases, etoposide in one. Chromosomal translocations involving 11q23 were observed relating to two secondary leukaemias from a total of six for which there were successful cytogenetic studies after administration of an epipodophyllotoxin. CONCLUSIONS--Epipodophyllotoxins acting alone or together with alkylating agents or radiation seem to be involved in secondary leukaemia after childhood cancer.     

Mortality of employees of the Atomic Weapons Establishment, 1951-82.

A total of 22,552 workers employed by the Atomic Weapons Establishment between 1951 and 1982 were followed up for an average of 18.6 years. Of the 3115 who died, 865 (28%) died of cancer. Mortality was 23% lower than the national average for all causes of death and 18% lower for cancer. These low rates were consistent with the findings in other workforces in the nuclear industry and reflect, at least in part, the selection of healthy people to work in the industry and the disproportionate recruitment of people from the higher social classes. At some time during their employment 9389 (42%) of the workers were monitored for exposure to radiation, the average cumulative whole body exposure to external radiation being 7.8 mSv. Their mortality was generally similar to that of other employees, even when exposures were lagged by 10 years. The rate ratio after a 10 year lag in workers with a radiation record compared with other workers was 1.01 (95% confidence interval 0.92 to 1.10) for all causes of death and 1.06 (0.89 to 1.27) for all malignant neoplasms. The only significant differences were for prostatic cancer (rate ratio 2.23; 95% confidence interval 1.13 to 4.40) and for cancers of ill defined and secondary sites (rate ratio 2.37; 1.23 to 4.56). Cancers of lymphatic and haemopoietic tissues were notable for their low occurrence in the study population, with only four deaths from leukaemia and two from multiple myeloma in workers with a radiation record, 9.16 and 3.55 deaths respectively being expected on the basis of national rates. Among workers who had a radiation record 3742 (40%) were also monitored for possible internal exposure to plutonium, 3044 (32%) to uranium, 1562 (17%) to tritium, 638 (7%) to polonium, and 281 (3%) to actinium. In these workers mortality from malignant neoplasms as a whole was not increased, but after a 10 year lag death rates from prostatic and renal cancers were generally more than twice the national average, these excesses arising in a small group of workers monitored for exposure to multiple radionuclides. Though mortality from lung cancer in workers monitored for exposure to plutonium was below the national average, it was some two thirds higher than in other radiation workers, the excess being of borderline statistical significance. Mortality from malignant neoplasms as a whole showed a weak and non-significant increasing trend with increasing level of cumulative whole body exposure to external radiation. When the exposures were lagged by 10 years the trend became stronger and significant, the estimated increase in relative risk per 10 mSv being 7.6% (95% confidence interval 0.4% to 15.3%). This trend was confined almost entirely to workers who were also monitored for exposure to radionuclides (p<0.001), the main contributions coming from lung cancer and prostatic cancer. Exposures of the lung and prostate from internal sources of radiation were not quantified, except for the contribution from tritium. It was therefore not possible to assess the extent to which the associations were due to internally deposited radionuclides rather than external exposure. The finding for prostatic cancer taken in conjunction with the results of other studies suggest a specific occupational hazard in a small group of workers in the nuclear industry who had comparatively high exposures to external radiation and who were also monitored for internal exposure to multiple radionuclides. Research is needed to discover whether any of the radionuclides and other substances concerned are concentrated in the prostate. The occurrence of lung cancer in this workforce requires further investigation taking into account smoking habits and tissue doses from inhaled radionuclides.     

Childhood leukaemia and non-Hodgkin's lymphoma near large rural construction sites,with a comparison with Sellafield nuclear site.

OBJECTIVE--To determine whether population mixing produced by large, non-nuclear construction projects in rural areas is associated with an increase in childhood leukaemia and non-Hodgkin''s lymphoma. DESIGN--A study of the incidence of leukaemia and non-Hodgkin''s lymphoma among children living near large construction projects in Britain since 1945, situated more than 20 km from a population centre, involving a workforce of more than 1000, and built over three or more calendar years. For periods before 1962 mortality was studied. SETTING--Areas within 10 km of relevant sites, and the highland counties of Scotland with many hydroelectric schemes. SUBJECTS--Children aged under 15. RESULTS--A 37% excess of leukaemia and non-Hodgkin''s lymphoma at 0-14 years of age was recorded during construction and the following calendar year. The excesses were greater at times when construction workers and operating staff overlapped (72%), particularly in areas of relatively high social class. For several sites the excesses were similar to or greater than that near the nuclear site of Sellafield (67%), which is distinctive in its large workforce with many construction workers. Seascale, near Sellafield, with a ninefold increase had an unusually high proportion of residents in social class I. The only study parish of comparable social class also showed a significant excess, with a confidence interval that included the Seascale excess. CONCLUSION--The findings support the infection hypothesis and reinforce the view that the excess of childhood leukaemia and non-Hodgkin''s lymphoma near Sellafield has a similar explanation.     

Rural population mixing and childhood leukaemia: effects of the North Sea oil industry in Scotland,including the area near Dounreay nuclear site.

OBJECTIVE--To determine if any excess of childhood leukaemia and non-Hodgkin''s lymphoma was associated with certain striking examples of population mixing in rural Scotland produced by the North Sea oil industry. DESIGN--Details were traced for over 30,000 workers involved in the construction of the large oil terminals in the Shetland and Orkney islands in northern Scotland or employed offshore. Home addresses of the 17,160 Scottish residents were postcoded, integrated with census data, and then classified as urban or rural. Rural postcode sectors, ranked by proportion of oil workers, were grouped into three categories with similar numbers of children but contrasting densities of oil workers. The incidence of leukaemia and non-Hodgkin''s lymphoma was examined in these rural (and also in urban) categories in the periods 1974-8, 1979-83 and 1984-8. SETTING--Scotland. SUBJECTS--Young people below age 25. RESULTS--A significant excess of leukaemia and non-Hodgkin''s lymphoma was found in 1979-83 in the group of rural home areas with the largest proportion of oil workers, following closely on large increases in the workforce. The area near the Dounreay nuclear installation, where an excess of leukaemia is already well known, was within the rural high oil category. CONCLUSION--The findings support the infection hypothesis that population mixing can increase the incidence of childhood leukaemia in rural areas. They also suggest that the recent excess in the Dounreay-Thurso area is due to population mixing linked to the oil industry, promoted by certain unusual local demographic factors.     

Distribution of childhood leukaemias and non-Hodgkin's lymphomas near nuclear installations in England and Wales.

OBJECTIVE--To examine the relation between the risk of childhood leukaemia and non-Hodgkin''s lymphoma and proximity of residence to nuclear installations in England and Wales. DESIGN--Observed and expected numbers of cases were calculated and analysed by standard methods based on ratios of observed to expected counts and by a new statistical test, the linear risk score test, based on ranks and designed to be sensitive to excess incidence in close proximity to a putative source of risk. SETTING--Electoral wards within 25 km of 23 nuclear installations and six control sites that had been investigated for suitability for generating stations but never used. SUBJECTS--Children below age 15 in England and Wales, 1966-87. MAIN OUTCOME MEASURE--Registration of any leukaemia or non-Hodgkin''s lymphoma. RESULTS--In none of the 25 km circles around the installations was the incidence ratio significantly greater than 1.0. The only significant results for the linear risk score test were for Sellafield (P = 0.00002) and Burghfield (P = 0.031). The circles for Aldermaston and Burghfield overlap; the incidence ratio was 1.10 in each. One of the control sites gave a significant linear risk score test result (P = 0.020). All the tests carried out were one sided with P values estimated by simulation. CONCLUSION--There is no evidence of a general increase of childhood leukaemia or non-Hodgkin''s lymphoma around nuclear installations. Apart from Sellafield, the evidence for distance related risk is very weak.     

Complexities in Research on Fathering: Illustrations from the Tufts Study of Young Fathers

Theory and research suggest that the transition to parenthood is a major life transition, and that adaptation to the parenting role is influenced by a complex set of factors, including the relationship with the child's mother, family of origin, and how the father is situated within sociocultural contexts. The father–]mother relationship is particularly important for men making the transition to fatherhood. This study examined patterns of fathering among young fathers (15–24 years) and investigated how fathers' relationships with the mothers of their young children (infants and toddlers) were related to fathering. In general, higher quality father–mother relationships were related to greater father involvement with children; when mothers were perceived as barriers to involved fathering fathers also had less accurate and adaptive parenting knowledge, attitudes, and behavior. Person-centered analyses revealed quite complex relations between father–mother relationships and father–child interaction. One pattern showed strong positive father–mother relationships associated with a disengaged pattern of father–child interaction, while another pattern showed sensitive and positive father–child engagement in the context of negative or distant father–mother relationships. Four patterns of association between fathering and mother–father relationships were demonstrated. Results highlight the complexity of understanding fathering and family relationships among young fathers.     

Influence of paternal immunity on idiotype expression in offspring

The immune response of the rat to group A streptococcal carbohydrate (SACHO) and an associated idiotype, Id-1, was used to examine the effect of paternal immunity on Id-1 and SACHO-specific antibody expression by the offspring. First litters, conceived before immunization of the father, had significantly higher Id-1 levels than litters conceived by the same parental pairs after hyperimmunization of the father (P > 0.01). Total anti-SACHO levels were not affected. The effect appeared to be independent of the level of Id-1 expressed by the father or grandfather. No significant difference in Id-1 production was found between offspring of actively immune, neonatally Id-1 suppressed fathers and fathers expressing high levels of Id-1. We suggest that the paternal immunoregulatory influence acts via the maternal immune system to modify the idiotype repertoire expressed in the immune response of the offspring, and is not the result of genetic transmission of a trait acquired by the father. Some possible mechanisms of transmission are discussed.     

Mortality and occupational exposure to radiation: first analysis of the National Registry for Radiation Workers.

OBJECTIVE--To study cause specific mortality of radiation workers with particular reference to associations between fatal neoplasms and level of exposure to radiation. DESIGN--Cohort study. SETTING--United Kingdom. SUBJECTS--95,217 radiation workers at major sites of the nuclear industry. MAIN OUTCOME MEASURE--Cause of death. RESULTS--Most standardised mortality ratios were below 100: 83 unlagged, 85 with a 10 year lag for all causes; 84 unlagged, 86 lagged for all cancers; and 80 for all known other causes, indicating a "healthy worker effect." The deficit of lung cancer (75 unlagged, 76 lagged) was significant at the 0.1% level. Standardised mortality ratios were significantly raised (214 unlagged, 303 lagged) for thyroid cancer, but there was no evidence for any trend with external recorded radiation dose. Dose of external radiation and mortality from all cancers were weakly correlated (p = 0.10), and multiple myeloma was more strongly correlated (p = 0.06); for leukaemia, excluding chronic lymphatic, the trend was significant (p = 0.03; all tests one tailed). The central estimates of lifetime risk derived from these data were 10.0% per Sv (90% confidence interval less than 0 to 24%) for all cancers and 0.76% per Sv (0.07 to 2.4%) for leukaemia (excluding chronic lymphatic leukaemia). These are, respectively, 2.5 times and 1.9 times the risk estimates recommended by the International Commission on Radiological Protection, but 90% confidence intervals are large and the commission''s risk factors fall well within the range. The positive trend with dose for all cancers, from which the risk estimate was derived, was not significant. The positive association between leukaemia (except chronic lymphatic leukaemia) was significant and robust in subsidiary analyses. This study showed no association between radiation exposure and prostatic cancer. CONCLUSION--There is evidence for an association between radiation exposure and mortality from cancer, in particular leukaemia (excluding chronic lymphatic leukaemia) and multiple myeloma, although mortality from these diseases in the study population overall was below that in the general population. The central estimates of risk from this study lie above the most recent estimates of the International Commission on Radiological Protection for leukaemia (excluding chronic lymphatic leukaemia) and for all malignancies. However, the commission''s risk estimates are well within the 90% confidence intervals from this study. Analysis of combined cohorts of radiation workers in the United States indicated lower risk estimates than the commission recommends, and when the American data are combined with our analysis the overall risks are close to those estimated by the commission. This first analysis of the National Registry for Radiation Workers does not provide sufficient evidence to justify a revision in risk estimates for radiological protection purposes.     

Electron paramagnetic resonance measurements of absorbed dose in teeth from citizens of Ozyorsk

In 1945, within the frame of the Uranium Project for the production of nuclear weapons, the Mayak nuclear facilities were constructed at the Lake Irtyash in the Southern Urals, Russia. The nuclear workers of the Mayak Production Association (MPA), who lived in the city of Ozyorsk, are the focus of epidemiological studies for the assessment of health risks due to protracted exposure to ionising radiation. Electron paramagnetic resonance measurements of absorbed dose in tooth enamel have already been used in the past, in an effort to validate occupational external doses that were evaluated in the Mayak Worker Dosimetry System. In the present study, 229 teeth of Ozyorsk citizens not employed at MPA were investigated for the assessment of external background exposure in Ozyorsk. The annually absorbed dose in tooth enamel from natural background radiation was estimated to be (0.7 ± 0.3) mGy. For citizens living in Ozyorsk during the time of routine noble gas releases of the MPA, which peaked in 1953, the average excess absorbed dose in enamel above natural background was (36 ± 29) mGy, which is consistent with the gamma dose obtained by model calculations. In addition, there were indications of possible accidental gaseous MPA releases that affected the population of Ozyorsk, during the early and late MPA operation periods, before 1951 and after 1960.     

Can paternal preconceptional radiation account for the increase of leukaemia and non-Hodgkin's lymphoma in Seascale?

OBJECTIVE--To determine if the excess of leukaemia and non-Hodgkin''s lymphoma in Seascale is restricted to those born in the parish and whether it might be explained by the postulated relation with paternal preconceptional radiation. DESIGN--Comparison, separately for those born in the parish and those born elsewhere, of the numbers of these malignancies observed in Seascale with those expected on the basis of reference rates for England and Wales. Details of paternal radiation levels were sought for each case. SETTING--The parish of Seascale in west Cumbria. SUBJECTS--Residents of Seascale below age 25 years in the years 1951-91. MAIN OUTCOME MEASURES--The observed and expected numbers of cases of leukaemia and non-Hodgkin''s lymphoma within Seascale among those born there and among those born elsewhere. Also, the levels of any paternal preconceptional radiation associated with each case. RESULTS--A significant excess of leukaemia and non-Hodgkin''s lymphoma at ages 0-24 was found in Seascale in those who were born there (ratio of observed to expected cases 8.6 and 20.2 respectively; p < 0.01). This also applied to those not born there (7.2 and 16.5; p < 0.01), a group often regarded as not showing an excess. The estimates were then conservatively recalculated so as to overestimate the risks among those born in Seascale and underestimate them among those born elsewhere. On this basis the six cases in those born in Seascale compare with 0.38 expected (15.8; p < 0.001), of which two were associated with paternal preconceptional life-time levels of 100 mSv or greater and three others with levels of 90-99 mSv. Among those born elsewhere, there were five cases (expected 0.74; ratio 6.7, p < 0.01), of which only one was associated with a high level of such radiation. CONCLUSIONS--Paternal preconceptional radiation cannot be the sole cause of the excess in Seascale since it will not explain the excess among those born outside Seascale. It follows that, unless two causes are to be postulated, any single cause must be a factor other than paternal preconceptional radiation. On this basis, the association found among those born there, if not partly due to chance, may reflect an indirect relation with the true cause. The recent hypothesis about such paternal radiation has originated in a subgroup of the excess cases that have aroused concern.     

Association between incidence of non-Hodgkin's lymphoma and solar ultraviolet radiation in England and Wales.

OBJECTIVES--To examine whether the incidence of non-Hodgkin''s lymphoma in different areas of England and Wales is associated with levels of solar ultraviolet radiation. DESIGN--Geographically based study examining the association between incidence of non-Hodgkin''s lymphoma and estimated levels of solar ultraviolet radiation, controlling for social class and employment in agriculture. SETTING--59 counties in England and Wales. SUBJECTS--All registered cases of non-Hodgkin''s lymphoma during the period 1968-85. MAIN OUTCOME MEASURE--Age and sex adjusted odds ratio for non-Hodgkin''s lymphoma in each county. RESULTS--Incidence of non-Hodgkin''s lymphoma was significantly associated with solar ultraviolet radiation levels (P < 0.001), even after social class and employment in agriculture were controlled for (P = 0.004). In a comparison of counties in the highest and lowest quarters of solar ultraviolet radiation, the relative risk of non-Hodgkin''s lymphoma was 1.27 (95% confidence interval 1.24 to 1.29), rising to 1.34 (1.32 to 1.37) after adjustment for social class and employment in agriculture. CONCLUSIONS--The incidence of non-Hodgkin''s lymphoma in different areas of England and Wales is positively associated with levels of solar ultraviolet radiation. These results are consistent with the hypothesis that exposure to solar ultraviolet radiation increases the risk of non-Hodgkin''s lymphoma.     

Trends in infant leukaemia in West Germany in relation to in utero exposure due to the Chernobyl accident

A temporary increase in the incidence of infant leukaemia in Greece was reported by Petridou et al., which was attributed to in utero exposure to ionising radiation resulting from the Chernobyl accident. We performed a similar analysis based on the data of the German Childhood Cancer Registry in order to check whether the observation could be confirmed by means of independent data. Applying the same definitions as Petridou et al., we also observed an increased incidence of infant leukaemia in a cohort of children born after the Chernobyl accident. More detailed analyses, regarding areas with different contamination levels and dose rate gradients over time after the accident, showed, however, no clear trend with regard to exposure. It would therefore appear less likely that the observed effect was caused by exposure to ionising radiation due to the Chernobyl accident. Received: 30 January 1998 / Accepted in revised form: 23 April 1998