Childhood cancer in Cumbria

Obstetric Outcomes in West Cumberland Hospital: Is There a Risk from Sellafield?

A retrospective study was made of the obstetric outcome of 18,252 babies born in West Cumberland Hospital in the years 1975 to 1985. There were 934 premature births (before 37 weeks), 555 small for dates births (under 2.5 kg but not before 37 weeks), 167 stillbirths, 125 neonatal deaths and 236 reported congenital malformations. The 212 babies born to mothers from Seascale during that time were compared with the births to mothers from other areas in West Cumbria Health District in order to assess any adverse effect from possible radioactive discharge at nearby Sellafield. There was no evidence of any increased incidence of these outcomes in Seascale births. Adequate retrospective data on miscarriage rates were not available, but using indirect information on hospital inpatients, no statistically significant increased incidence was found, although the absolute numbers of miscarriage in Seascale were slightly higher than expected. From this evidence, no adverse effects on completed pregnancies can be attributed to the Sellafield plant of British Nuclear Fuels. However, a prospective study of miscarriage incidence in West Cumbria and near other nuclear installations is urgently needed.

Residential proximity of children with leukaemia and non-Hodgkin's lymphoma in three areas of northern England

A retrospective population-based case-control interview study has been conducted in three distinct areas in the north of England where local excesses of children with leukaemia have been reported. A total of 109 cases of childhood (0-14 years at diagnosis) leukaemia and non-Hodgkin's lymphoma who were born in one of the study areas and diagnosed there between 1974 and 1988 were included in the study. One control per case was matched on sex, date-of-birth and health district of birth. The objective was to compare residential histories of cases and controls and in particular to determine whether case children had lived in the same place at the same time more often than controls. The residential distance between two children was taken to be the smallest geographical distance between homes they had 'occupied' simultaneously for a period of at least 6 months between conception and diagnosis. Case children were more likely than expected to have other cases as their nearest neighbours by residential distance (observed = 69, expected = 54.5, P = 0.006). A detailed examination of the nearest neighbour pattern permits the generation of further specific hypotheses. These suggest that persistent infection established in utero or early infancy may be involved in the development of some cases of childhood leukaemia. Horizontal transmission of the agent(s) within small communities may occur but there is no evidence of direct contact between cases.

Parental occupations of children with leukaemia in west Cumbria, north Humberside, and Gateshead

OBJECTIVE

To determine whether parental occupations and chemical and other specific exposures are risk factors for childhood leukaemia.

DESIGN

Case-control study. Information on parents was obtained by home interview.

SETTING

Three areas in north England: Copeland and South Lakeland (west Cumbria); Kingston upon Hull, Beverley, East Yorkshire, and Holderness (north Humberside), and Gateshead.

SUBJECTS

109 children aged 0-14 born and diagnosed as having leukaemia or non-Hodgkin's lymphoma in study areas during 1974-88. Two controls matched for sex and date and district of birth were obtained for each child.

MAIN OUTCOME MEASURES

Occupations of parents and specific exposure of parents before the children's conception, during gestation, and after birth. Other adults living with the children were included in the postnatal analysis.

RESULTS

Few risk factors were identified for mothers, although preconceptional association with the food industry was significantly increased in case mothers (odds ratio 2.56; 95% confidence interval 1.32 to 5.00). Significant associations were found between childhood leukaemia and reported preconceptional exposure of fathers to wood dust (2.73, 1.44 to 5.16), radiation (3.23, 1.36 to 7.72), and benzene (5.81, 1.67 to 26.44); ionising radiation alone gave an odds ratio of 2.35 (0.92 to 6.22). Raised odds ratios were found for paternal exposure during gestation, but no independent postnatal effect was evident.

CONCLUSION

These results should be interpreted cautiously because of the small numbers, overlap with another study, and multiple exposure of some parents. It is important to distinguish periods of parental exposures; identified risk factors were almost exclusively restricted to the time before the child's birth.

On statistical methods for analysing the geographical distribution of cancer cases near nuclear installations

There is great public concern, often based on anecdotal reports, about risks from ionising radiation. Recent interest has been directed at an excess of leukaemia cases in the locality of civil nuclear installations at Sellafield and Sizewell, and epidemiologists have a duty to pursue such information vigorously. This paper sets out to show that the epidemiological methods most commonly used can be improved upon. When analysing geographical data it is necessary to consider location. The most obvious quantification of location is ranked distance, though other measures which may be more meaningful in relation to aetiology may be substituted. A test based on distance ranks, the "Poisson maximum test", depends on the maximum of observed relative risk in regions of increasing size, but with significance level adjusted for selection. Applying this test to data from Sellafield and Sizewell shows that the excess of leukaemia incidence observed at Seascale, near Sellafield, is not an artefact due to data selection by region, and that the excess probably results from a genuine, if as yet unidentified cause (there being little evidence of any other locational association once the Seascale cases have been removed). So far as Sizewell is concerned, geographical proximity to the nuclear power station does not seem particularly important.

Evidence for an infective cause of childhood leukaemia: comparison of a Scottish new town with nuclear reprocessing sites in Britain

Increases of leukaemia in young people that cannot be explained in terms of radiation have been recorded near both of Britain's nuclear reprocessing plants at Dounreay and Sellafield. These were built in unusually isolated places where herd immunity to a postulated widespread virus infection (to which leukaemia is a rare response) would tend to be lower than average. The large influxes of people in the 1950s to those areas might have been conducive to epidemics. The hypothesis has been tested in Scotland in an area identified at the outset as the only other rural area that received a large influx at the same time, when it was much more cut off from the nearest conurbation than at present--the New Town of Glenrothes. A significant increase of leukaemia below age 25 was found (10 observed, expected 3.6), with a greater excess below age 5 (7 observed, expected 1.5).

Childhood cancer in the Northern Region, 1968-82: incidence in small geographical areas

The place of residence of all cases of childhood cancer occurring in the Northern Region from 1968 to 1982 has been analysed by electoral wards. The wards have been ranked according to rate and Poisson probability. Both rankings show a wide geographical scatter throughout the region of areas with an apparent excess incidence of cancer. These areas are not confined to the Cumbrian coast.