The Committee examined reports on whether there were increased leukaemia risks among people who lived around estuaries. Data obtained from the Leukaemia Research Fund (LRF) Data Collection Study (DCS) for 1984 -1986, suggested a raised incidence of leukaemia at all ages in estuaries compared with inland areas, and coastal wards showed a decreased incidence of leukaemia, although both with only a marginal level of statistical significance. However a similar study investigating DCS data from later years questioned the quality of the DCS data collection, as it was not maintained to an equal standard in all areas. Further, some areas included originally were not considered later, and some areas previously excluded were included later. In addition, the DCS data had truncated ages that differed over time: age 84 for the earlier data and 79 for the later data. The later study suggested no significant elevation of leukaemia in estuarine wards for either all leukaemia or childhood leukaemia compared with inland. The data had been broken down into mud, mouth and tidal areas for estuaries; the small increases for mud and mouth areas were not statistically significant. Overall, the Committee considered that no reliable conclusions could be drawn about the risk of leukaemia near estuaries from the DCS analyses.

The DCS studies and their data raised concerns among some members of the committee about certain other decisions concerning epidemiological studies, such as the failure of the UKCCS to look at environmental releases of radioactivity.

It was suggested that a further study of similar design to the DCS studies would be useful. Such a study, using data from the UKCCS, had been suggested by Dr Roman and the Committee would contact her over the protocols for the study.


Continuing its discussions on Dr Busby’s second event theory, the Committee considered the biological plausibility of the SET. It considered a review of the extent to which experimental data supported or opposed the requirement of the second event theory (SET) that radiation should stimulate resting cells into replication. The review had been unable to find any references to activation of resting cells by small doses of radiation. The report examined the sensitive G2/M phase of the cell cycle, looking at mutations, chromosome aberrations, and transformations: there was nothing to indicate the huge radiosensitivity required by the SET. The review concluded there was no evidence for the effects suggested by or required by the second event theory.


The Committee discussed proposed research into the binding of strontium-90 to DNA. This binding may occur to either the base pair structure or the chromatin-protein scaffolding; not finding a preferential binding in the former case would not necessarily disqualify the theory. The detrimental effect of strontium would depend on whether it was bound to the DNA, folded in its structure, or attached to one of the proteins in DNA. In principle, there would be a large difference in potential effect between strontium on the DNA molecule, or slightly further away on its chromatin. The Committee also discussed the possibility of conducting an in vivo experiment measuring chromosome aberrations in bone marrow, for comparison with previous studies in which an effect on bone marrow cellularity in rats had been reported at doses as low as about 1 mGy. Discussions centred on transmutation effects, ionising events, strontium-90 and strontium-89 carcinogenesis and experiments that studied genetic damage in mice due to the injection of radionuclides. They agreed to suggest experiments for further research, which would include radionuclides other than strontium-90.


The Committee continued its examination of studies investigating childhood leukaemia in Nordic countries following test bomb fallout in the 1950s and 1960s. Further investigation was suggested to determine whether the apparent increase in infant leukaemia incidence in Denmark in the 1960s was real or a result of reporting methods, improved diagnostics or other data biases. Denmark had a small database of infant and childhood leukaemia and few excess cases due to fallout were expected because of Denmark’s low rainfall. It was noted that, prior to 1970, a substantial proportion of childhood leukaemia cases in Denmark were “type unspecified”. Later studies showed that although the incidence rate of “all leukaemias" was approximately constant with time, "unspecified leukaemias" decreased with time, and “acute leukaemias" correspondingly increased. The suggested reason is that initially a large proportion of childhood leukaemias were of an unspecified type, but later these were more likely to be classified as acute leukaemia as diagnostic criteria improved.


The Committee discussed the possible association of airborne tritium emissions from nuclear plants with apparent increases in lagged neonatal deaths nearby. A study by a "citizen scientist", which had not been published in a peer review journal, had been examined by an independent academic who had concluded that the "citizen scientist" had not proved his case but, in the absence of available information, the matter should receive further investigation. The Committee considered this was a subject for further research. They decided to keep the matter under review and to consider it further at future meetings.

Next (Meeting 9)