Gender ratio of offspring and exposure to shortwave radiation among female physiotherapists.

OBJECTIVES: The goal of this study was to investigate whether the deficit of male births found among the offspring of Danish physiotherapists exposed to shortwave radiation during the first month of their pregnancy could be confirmed among the offspring of physiotherapists from Switzerland. METHODS: A self-administrated questionnaire was mailed (two mailings) to all of the 2846 female members of the Swiss Federation of Physiotherapists. It included questions on the gender and birth-weight of all children of the physiotherapists, as well as on the use of shortwave or microwave equipment during the first month of each pregnancy. The response rate was 79.5%, and the analysis was based on 1781 pregnancies. RESULTS: The gender ratio (the number of males per number of females x 100) was 107 with a 95% confidence interval (95% CI) of 89-127 for the 508 pregnancies exposed to shortwave radiation and 101 (95% CI 90-113) for the 1273 unexposed pregnancies. There was no trend in the gender ratio with increasing intensity or duration of exposure. The prevalence of low birthweight (< or = 2500 g) was not related to exposure to shortwave radiation for either the boys or the girls. CONCLUSIONS: No atypical gender ratio was found for the children of female physiotherapists from Switzerland who had been exposed to shortwave radiation at the beginning of pregnancy. The findings of the Danish study could not be confirmed.

A method for determining simultaneously the dose and the elapsed time since irradiation using TLDs.

Information about the time that has elapsed since an external radiation exposure is useful in order to determine the time of occurrence of an abnormal exposure in personal and accidental dosimetry is presented. This information can be obtained from certain irradiated thermoluminescent dosimeters. A computational method based on decay rates of thermoluminescence glow peaks has been used to estimate a range of suitable values of trap lifetimes of low temperature glow peaks. This provides a basis for the selection of an appropriate thermoluminescent material to assess not only the absorbed dose from a radiation exposure, but also the elapsed time. Experimental studies have been used to obtain additional information on decay rates as a function of energy, temperature and absorbed dose.

The biological effect of very high energy hadrons.

The meristems of Vicia faba bean roots were irradiated at different depths in water in a 250 GeV/c positive hadron beam from the CERN Super Proton Synchrotron (SPS). The growth during the 10 days following irradiation was determined and compared with results obtained from 60Co gamma-ray exposures. The data indicate a Relative Biological Efficiency (r.b.e.) near to one, independent of the contribution of secondaries to the dose. However, some anomalies in the radiation response of the irradiated beans were noted.

RBE and OER values of negative pion beams from growth inhibition of Vicia faba roots.

Two pion beams of different momentum width have been used to expose meristems of Vicia Faba roots under aerobic and hypoxic conditions. The measurements of the resulting 10 days growth inhibition after exposures at various locations on the pion beam axes have been made and RBE and OER values evaluated for 50% effects compared to 60Co gamma-rays. The results have been related to the fractional doses from star products defined by telescope measurements of stopped pions along the same beams. It has been found that the RBE value increases with the fractional "star dose" up to a maximum after which the RBE decreases. The OER values, however, were found to decrease with increasing "star dose" fraction rather rapidly after which it was found to be independent of the "star dose" contribution.