Scope of the Workshop

Childhood leukemia is a heterogeneous disease and the most common malignancy in children accounting for around one third of all childhood cancer cases below the age of 15 years. The causes of most leukemias are still unknown, but both genetic and environmental factors have been implicated in the aetiology of the disease.

Ionizing radiation is regarded as an established environmental risk factor, found in epidemiological studies and confirmed by experimental data. At the same time data on an increased incidence of childhood leukemia near nuclear facilities are puzzling experts, because the exposures in relation to the case numbers are too low to be considered causal.

Non-ionizing radiation has been studied as a possible risk factor since more than 30 years. No carcinogenic potential of low-level fields (levels below ICNIRP recommendations) has been revealed in experimental studies. However, a consistent pattern of a two-fold increase in childhood leukemia is observed in epidemiological studies associated with average exposure to residential low-frequency magnetic fields above 0,3-0,4 µT. The epidemiological evidence is weakened by methodological limitations and no accepted or even plausible biophysical mechanism challenging the crucial question of causal relationship are currently available.

The apparent inconsistencies between empirical findings and the lack of supportive experimental data have to be considered in the light of other possible risk factors and of new data on the complex origin of childhood leukemia. A number of recent studies supports the hypothesis that initiation of the disease arises prenatally and that exposures before birth or early in life and/or an abnormal immune response play an important role in its further manifestation.

The international workshop will bring together experts from different disciplines and backgrounds in order to summarize the current knowledge on all known risk factors and the recent hypothesis on the aetiology of childhood leukemia. The workshop is intended to help the organizers and other experts in radiation protection to assess the statistical associations observed frequently or consistently at low dose/low level areas in epidemiological studies.