Follow up study of children born to mothers resident in Seascale,West Cumbria (birth cohort).

Records on 1068 children who were born to mothers resident in Seascale Civil Parish during 1950-83 were studied. There was a large degree of mobility among the families, and nearly half of the children did not subsequently attend the main local school. Use of the National Health Service Central Register, however, enabled us to follow up the children''s records regardless of place of residence. The excess of leukaemia among Seascale children first supported from the analysis of geographical areas is confirmed. There were five deaths from leukaemia identified to 30 June 1986 compared with 0.53 expected at national rates--a ratio of 9.36 (95% confidence interval 3.04 to 21.84). One of these deaths occurred after the child had left Seascale. There were four deaths from other cancers compared with 1.06 expected--a ratio of 3.76 (95% CI 1.02 to 9.63). In addition, three further cases of cancer, apart from the deaths, were reported compared with 1.19 expected since 1971--a ratio of 2.53 (95% CI 0.52 to 7.40). For other causes of death, including stillbirths and infant mortality, there was a reported deficit compared with national rates, some of which at least was to be expected on the basis of the social class composition of the population of Seascale. In view of the importance of this cohort of births continued follow up is planned, with the possibility of extending it to include births since 1983, and the methods available for this type of study will be examined further.     

Population based survival rates for childhood cancer in Britain, 1980-91.

OBJECTIVES--To investigate the survival of children with cancer diagnosed during 1980-91 in order to assess the impact of developments in medical care on a population basis. DESIGN--Retrospective cohort study. SETTING--Great Britain. SUBJECTS--14973 children with cancer diagnosed during 1980-91 and included in the population based National Registry of Childhood Tumours. MAIN OUTCOME MEASURES--Actuarial survival rates. RESULTS--For all cancers combined, two year survival increased from 66% to 76% between 1980-2 and 1989-91, and five year survival increased from 57% to 65% between 1980-2 and 1986-8. Significant increases in survival rates occurred among children with acute lymphoblastic leukaemia, acute nonlymphocytic leukaemia, retinoblastoma, osteosarcoma, Ewing''s sarcoma, rhabdomyosarcoma, and malignant gonadal germ cell tumours. No trend in survival was seen for children with Hodgkin''s disease, central nervous system tumours, neuroblastoma, or Wilms''s tumour. CONCLUSIONS--Nearly two thirds of children who have cancer diagnosed can now expect to survive at least 10 years.     

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.     

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.     

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.     

Reducing Neonatal Mortality in India: Critical Role of Access to Emergency Obstetric Care

Background

Neonatal mortality currently accounts for 41% of all global deaths among children below five years. Despite recording a 33% decline in neonatal deaths between 2000 and 2009, about 900,000 neonates died in India in 2009. The decline in neonatal mortality is slower than in the post-neonatal period, and neonatal mortality rates have increased as a proportion of under-five mortality rates. Neonatal mortality rates are higher among rural dwellers of India, who make up at least two-thirds of India''s population. Identifying the factors influencing neonatal mortality will significantly improve child survival outcomes in India.

Methods

Our analysis is based on household data from the nationally representative 2008 Indian District Level Household Survey (DLHS-3). We use probit regression techniques to analyse the links between neonatal mortality at the household level and households'' access to health facilities. The probability of the child dying in the first month of birth is our dependent variable.

Results

We found that 80% of neonatal deaths occurred within the first week of birth, and that the probability of neonatal mortality is significantly lower when the child''s village is closer to the district hospital (DH), suggesting the critical importance of specialist hospital care in the prevention of newborn deaths. Neonatal deaths were lower in regions where emergency obstetric care was available at the District Hospitals. We also found that parental schooling and household wealth status improved neonatal survival outcomes.

Conclusions

Addressing the main causes of neonatal deaths in India – preterm deliveries, asphyxia, and sepsis – requires adequacy of specialised workforce and facilities for delivery and neonatal intensive care and easy access by mothers and neonates. The slow decline in neonatal death rates reflects a limited attention to factors which contribute to neonatal deaths. The suboptimal quality and coverage of Emergency Obstetric Care facilities in India require urgent attention.     

Doctor,you're in tobacco sales!

The director of British Columbia''s Doctors'' Stop-Smoking Project says that, whether they recognize it or not, doctors have the best and most competitive position within the tobacco industry because they have the best product line. Dr. Frederic Bass says physicians'' products—health and freedom from addiction—will win against the competition, which can offer only smoke, addiction to nicotine and ill health. “We offer the better deal,” he says, “but are we selling like we could? That''s the issue.”     

Epidemiology of chickenpox in England and Wales, 1967-85

Routine sources of data on chickenpox morbidity and mortality in England and Wales were reviewed for 1967-85. Only two epidemics occurred, one in 1967 and one in 1980, both of which were immediately followed by two to three years of low incidence. The age distribution of the disease appears to be changing, with more cases now being reported in children aged 0-4 years. The number of deaths in adults have, however, increased, particularly those deaths that are associated with pneumonia and immunosuppression. At present in England and Wales more deaths are attributed to chickenpox than to whooping cough and mumps.Widespread use of selective immunisation against chickenpox might be justified in England and Wales, but before routine immunisation of the child population can be considered special surveys to determine the incidence and severity of chickenpox and the effect of the vaccine on the subsequent development of herpes zoster are needed as well as cost-benefit studies of immunisation.     

Young Children's Probability of Dying Before and After Their Mother's Death: A Rural South African Population-Based Surveillance Study

Background

There is evidence that a young child''s risk of dying increases following the mother''s death, but little is known about the risk when the mother becomes very ill prior to her death. We hypothesized that children would be more likely to die during the period several months before their mother''s death, as well as for several months after her death. Therefore we investigated the relationship between young children''s likelihood of dying and the timing of their mother''s death and, in particular, the existence of a critical period of increased risk.

Methods and Findings

Data from a health and socio-demographic surveillance system in rural South Africa were collected on children 0–5 y of age from 1 January 1994 to 31 December 2008. Discrete time survival analysis was used to estimate children''s probability of dying before and after their mother''s death, accounting for moderators. 1,244 children (3% of sample) died from 1994 to 2008. The probability of child death began to rise 6–11 mo prior to the mother''s death and increased markedly during the 2 mo immediately before the month of her death (odds ratio [OR] 7.1 [95% CI 3.9–12.7]), in the month of her death (OR 12.6 [6.2–25.3]), and during the 2 mo following her death (OR 7.0 [3.2–15.6]). This increase in the probability of dying was more pronounced for children whose mothers died of AIDS or tuberculosis compared to other causes of death, but the pattern remained for causes unrelated to AIDS/tuberculosis. Infants aged 0–6 mo at the time of their mother''s death were nine times more likely to die than children aged 2–5 y. The limitations of the study included the lack of knowledge about precisely when a very ill mother will die, a lack of information about child nutrition and care, and the diagnosis of AIDS deaths by verbal autopsy rather than serostatus.

Conclusions

Young children in lower income settings are more likely to die not only after their mother''s death but also in the months before, when she is seriously ill. Interventions are urgently needed to support families both when the mother becomes very ill and after her death. Please see later in the article for the Editors'' Summary     

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.     

Education and Eminence in British Medicine

The educational background of eminent members of the British medical profession was examined by recourse to Who''s Who. Substantial differences in background were found among the various medical specialties. Members of specialties enjoying high prestige within the profession—physicians, surgeons—were more likely than other members of the sample to have been to an English school as opposed to one in Scotland, Wales, or Northern Ireland, and to a headmasters'' conference school as opposed to a grammar school. Educational background was also found to relate to the aspect of the patient''s body on which specialists normally worked. Specialists coming from English headmasters'' conference schools were more likely than others to work on living bodies rather than dead bodies or parts of bodies, on the head rather than on the lower trunk, on male bodies rather than female bodies, and on the body''s surface rather than its inside.     

Immune Deficiency,Thrombocytopenia and Osteomyelitis in Pediatric Patients

Surgical decompression of osteomyelitis in pediatric patients should be an essential part of therapy in most cases. The initial deferral of prompt decompression in two patients because of underlying chronic, hemorrhagic (thrombocytopenic) disorders—one with Wiskott-Aldrich syndrome and one with Gaucher''s disease—resulted in more serious and prolonged courses of the infectious processes. The complications might have been ameliorated by earlier drainage in each case. Based upon the experience gained from these two patients, we recommend early drainage, with appropriate treatment of the hemorrhagic disorder, to prevent more widespread dissemination or prolongation of osseous infection in similarly affected children.     

Major Radiodiagnostic Imaging in Pregnancy and the Risk of Childhood Malignancy: A Population-Based Cohort Study in Ontario

Background

The association between fetal exposure to major radiodiagnostic testing in pregnancy—computed tomography (CT) and radionuclide imaging—and the risk of childhood cancer is not established.

Methods and Findings

We completed a population-based study of 1.8 million maternal-child pairs in the province of Ontario, from 1991 to 2008. We used Ontario''s universal health care–linked administrative databases to identify all term obstetrical deliveries and newborn records, inpatient and outpatient major radiodiagnostic services, as well as all children with a malignancy after birth. There were 5,590 mothers exposed to major radiodiagnostic testing in pregnancy (3.0 per 1,000) and 1,829,927 mothers not exposed. The rate of radiodiagnostic testing increased from 1.1 to 6.3 per 1,000 pregnancies over the study period; about 73% of tests were CT scans. After a median duration of follow-up of 8.9 years, four childhood cancers arose in the exposed group (1.13 per 10,000 person-years) and 2,539 cancers in the unexposed group (1.56 per 10,000 person-years), a crude hazard ratio of 0.69 (95% confidence interval 0.26–1.82). After adjusting for maternal age, income quintile, urban status, and maternal cancer, as well as infant sex, chromosomal or congenital anomalies, and major radiodiagnostic test exposure after birth, the risk was essentially unchanged (hazard ratio 0.68, 95% confidence interval 0.25–1.80).

Conclusions

Although major radiodiagnostic testing is now performed in about 1 in 160 pregnancies in Ontario, the absolute annual risk of childhood malignancy following exposure in utero remains about 1 in 10,000. Since the upper confidence limit of the relative risk of malignancy may be as high as 1.8 times that of an unexposed pregnancy, we cannot exclude the possibility that fetal exposure to CT or radionuclide imaging is carcinogenic. Please see later in the article for the Editors'' Summary     

Epilepsy and Pregnancy: A Report from the Oxford Record Linkage Study

The files of the Oxford Record Linkage Study were used to identify 223 infants delivered to 168 epileptic women as the result of 218 pregnancies. There were six stillbirths, two of which were grossly malformed. It was shown that the population of epileptic mothers differed significantly from the total reproducing population in respect of social class. Each pregnancy resulting in a livebirth was therefore matched exactly for social class, civil status, maternal age, parity, hospital, and year of delivery with three control deliveries resulting in livebirths. The defects noted at birth were abstracted from the Record Linkage files, and any subsequent hospital admissions or deaths of the children were also abstracted.There were highly significant excesses of congenital abnormalities among the infants born to epileptic mothers (13·8% of livebirths had some degree of defect of congenital origin compared with 5·6% of controls, P <0·0005). It was shown that neither the frequency with which the mother had fits nor the length of time she had had the epilepsy seemed to bear any relation to the frequency of defects in the offspring—with the exception of the two mothers who developed epilepsy in the first     

Combined Impact of Lifestyle-Related Factors on Total and Cause-Specific Mortality among Chinese Women: Prospective Cohort Study

Background

Although cigarette smoking, excessive alcohol drinking, obesity, and several other well-studied unhealthy lifestyle-related factors each have been linked to the risk of multiple chronic diseases and premature death, little is known about the combined impact on mortality outcomes, in particular among Chinese and other non-Western populations. The objective of this study was to quantify the overall impact of lifestyle-related factors beyond that of active cigarette smoking and alcohol consumption on all-cause and cause-specific mortality in Chinese women.

Methods and Findings

We used data from the Shanghai Women''s Health Study, an ongoing population-based prospective cohort study in China. Participants included 71,243 women aged 40 to 70 years enrolled during 1996–2000 who never smoked or drank alcohol regularly. A healthy lifestyle score was created on the basis of five lifestyle-related factors shown to be independently associated with mortality outcomes (normal weight, lower waist-hip ratio, daily exercise, never exposed to spouse''s smoking, higher daily fruit and vegetable intake). The score ranged from zero (least healthy) to five (most healthy) points. During an average follow-up of 9 years, 2,860 deaths occurred, including 775 from cardiovascular disease (CVD) and 1,351 from cancer. Adjusted hazard ratios for mortality decreased progressively with an increasing number of healthy lifestyle factors. Compared to women with a score of zero, hazard ratios (95% confidence intervals) for women with four to five factors were 0.57 (0.44–0.74) for total mortality, 0.29 (0.16–0.54) for CVD mortality, and 0.76 (0.54–1.06) for cancer mortality. The inverse association between the healthy lifestyle score and mortality was seen consistently regardless of chronic disease status at baseline. The population attributable risks for not having 4–5 healthy lifestyle factors were 33% for total deaths, 59% for CVD deaths, and 19% for cancer deaths.

Conclusions

In this first study, to our knowledge, to quantify the combined impact of lifestyle-related factors on mortality outcomes in Chinese women, a healthier lifestyle pattern—including being of normal weight, lower central adiposity, participation in physical activity, nonexposure to spousal smoking, and higher fruit and vegetable intake—was associated with reductions in total and cause-specific mortality among lifetime nonsmoking and nondrinking women, supporting the importance of overall lifestyle modification in disease prevention. Please see later in the article for the Editors'' Summary     

Reported Influenza in Pregnancy and Subsequent Cancer in the Child

A longitudinal study of 1,959 infants born in the first week of March 1958 to mothers who were reported to have had influenza during pregnancy revealed an incidence of cancer of 4·1 per 1,000 compared with only 0·8 per 1,000 among the 14,791 infants of mothers who had not had influenza.This increase was caused by cases of leukaemia and other neoplasms of lymphatic and haematopoietic tissue (I.C.D. 200-209) (P <0·0001).Data from the reports of the Registrar General for England and Wales were used to estimate the number of infants born in each year from 1955 to 1964 who subsequently died of cancer before 5 years of age. The rates for each year were compared with an estimate of the prevalence of influenza during the preceding winter. After allowing for the overall trend in the cancer death rate, a highly significant correlation was shown with deaths attributed to causes classified as I.C.D. 200-209 (P <0·005), but not with deaths attributed to other cancers. The increase in the risk of developing these neoplasms among children whose mothers had influenza is estimated to be not less than fourfold. Even so the risk remains small (3 to 4 per 1,000).     

Familial cancer on a Scottish island.

When the causes of death were determined in 18 relations of a child with Fanconi''s anaemia 10 deaths were found to be due to carcinoma of various organs. Cases of osteogenic sarcoma, leukaemia, and Marfan''s syndrome were also discovered among relatives. The family was from a remote community in the hebrides and there was considerable intermarriage. Suggestive evidence of heterozygosity was found by chromosome analysis.     

Maternal fatness and viability of preterm infants

To investigate the effect of maternal fatness on the mortality of infants born preterm up to the corrected age of 18 months 795 mother-infant pairs were studied. Maternal fatness was defined by Quetelet''s index (weight/(height²)) and all infants weighed less than 1850 g at birth. In 771 mother-infant pairs maternal age, complications of pregnancy, mode of delivery, parity, social class, and the baby''s sex and gestation were analysed by a logistic regression model for associations with infant mortality (but deaths from severe congenital abnormalities and those occurring during the first 48 hours after birth were excluded). In a subgroup of 284 mother-infant pairs all infant deaths except those from severe congenital abnormalities were analysed in association with the infant''s birth weight and gestation and the mother''s height and weight; this second analysis included another 24 infants who had died within 48 hours after birth. In the first analysis mortality overall was 7% (55/771), rising from 4% (71/173) in thin mothers (Quetelet''s index <20) to 15% (6/40) in mothers with grades II and III obesity (Quetelet''s index >30). After adjusting for major demographic and antenatal factors, including serious complications of pregnancy, maternal fatness was second in importance only to length of gestation in predicting death of infants born preterm. In the second analysis mortality overall was 15% (44/284), rising from 9% (5/53) in thin mothers to 47% (8/17) in mothers with grades II and III obesity. In both analyses the relative risk of death by 18 months post-term was nearly four times greater in infants born to obese mothers than in those born to thin mothers. In addition, maternal fatness was associated with reduced birth weight, whereas it is associated with macrosomia in term infants.These data differ fundamentally from those reported in full term babies of obese mothers. It is speculated that the altered metabolic milieu in obesity may reduce the ability of the fetus to adapt to extrauterine life if it is born preterm.     

Case-control study of leukaemia and non-Hodgkin's lymphoma among children aged 0-4 years living in west Berkshire and north Hampshire health districts.

OBJECTIVE--To investigate the relation between parental employment in the nuclear industry and childhood leukaemia and non-Hodgkin''s lymphoma. DESIGN--Case-control study. SETTING-West Berkshire and Basingstoke and North Hampshire District Health Authorities. SUBJECTS--54 children aged 0-4 years who had leukaemia or non-Hodgkin''s lymphoma diagnosed during 1972-89, who were born in the study area and were resident there when cancer was diagnosed. Six controls were selected for each case: four from hospital delivery registers and two from livebirth registers maintained by the NHS central register. Controls were matched for sex, date of birth (within six months), and area of residence at birth and time of diagnosis. MAIN OUTCOME MEASURES--Parents'' employment by the nuclear industry and exposure to ionising radiation at work. RESULTS--Five (9%) of the 54 cases and 14 (4%) of the 324 controls had fathers or mothers, or both, who had been employed by the nuclear industry (relative risk 2.2, 95% confidence interval 0.6 to 6.9). Nuclear industry employees who work in areas where exposure to radiation is possible are given film badges to monitor their exposure to external penetrating ionising radiation. Three fathers of cases and two fathers of controls (and no mothers of either) had been monitored in this way before their child was conceived (relative risk 9.0, 95% confidence interval 1.0 to 107.8). No father (of a case or control) had accumulated a recorded dose of more than 5 mSv before his child was conceived, and no father had been monitored at any time in the four years before his child was conceived. A dose-response relation was not evident among fathers who had been monitored. CONCLUSIONS--These results suggest that the children of fathers who had been monitored for exposure to external penetrating ionising radiation in the nuclear industry may be at increased risk of developing leukaemia before their fifth birthday. The finding is based on small numbers and could be due to chance. If the relationship is real the mechanisms are far from clear, except that the effect is unlikely to be due to external radiation; the possibility that it could be due to internal contamination by radioactive substances or some other exposure at work should be pursued. The above average rates of leukaemia in the study area cannot be accounted for by these findings.     

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.