Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis

Abstract

BackgroundThe ratio of male to female offspring at birth may be a simple and non-invasive way to monitor the reproductive health of a population. Except in societies where selective abortion skews the sex ratio, approximately 105 boys are born for every 100 girls. Generally, the human sex ratio at birth is remarkably constant in large populations. After the Chernobyl nuclear power plant accident in April 1986, a long lasting significant elevation in the sex ratio has been found in Russia, i.e. more boys or fewer girls compared to expectation were born. Recently, also for Cuba an escalated sex ratio from 1987 onward has been documented and discussed in the scientific literature.Presentation of the hypothesisBy the end of the eighties of the last century in Cuba as much as about 60% of the food imports were provided by the former Soviet Union. Due to its difficult economic situation, Cuba had neither the necessary insight nor the political strength to circumvent the detrimental genetic effects of imported radioactively contaminated foodstuffs after Chernobyl. We propose that the long term stable sex ratio increase in Cuba is essentially due to ionizing radiation.Testing of the hypothesisA synoptic trend analysis of Russian and Cuban annual sex ratios discloses upward jumps in 1987. The estimated jump height from 1986 to 1987 in Russia measures 0.51% with a 95% confidence interval (0.28, 0.75), p value < 0.0001. In Cuba the estimated jump height measures 2.99% (2.39, 3.60), p value < 0.0001. The hypothesis may be tested by reconstruction of imports from the world markets to Cuba and by radiological analyses of remains in Cuba for Cs-137 and Sr-90.Implications of the hypothesisIf the evidence for the hypothesis is strengthened, there is potential to learn about genetic radiation risks and to prevent similar effects in present and future exposure situations.

Letter to the Editor

“…However, the findings presented by Victor Grech must not be considered in isolation, they are rather consistent with early observations after the atomic bombing of Japan, and are clearly in line with our results after Chernobyl and in the vicinity of nuclear facilities [8,9,17,23,24]. The relief of ionizing radiation as a possible culprit for the sex ratio increases after radiological events offered by Jargin: social factors and negligibility of doses is not convincing as gradually changing social factors cannot entail abrupt sex ratio changes and a doubling of the background radiation is certainly not trivial.…”

The Influence of Migration on Secular Trends in Sex Ratios at Birth in Cuba in the Past Fifty Years

“…This has been attributed to having caused a paradoxical rise in M/F (17). It has also been hypothesized that this rise in M/F could have been caused by radioactively contaminated food imports from Russia by the Chernobyl accident of April 1986 (14), a plausible albeit unproven possibility (18). This hypothesis is supported by the fact that the increase in M/F between 1986 and 1989 is paralleled by a decline in total births over the same period (Table 4).…”

Sex ratios at birth after induced abortion

“…2,3 Modest variations in the natural male:female ratio have been linked to demographic, biologic and environmental factors, 2,4-6 including wartime and environmental disasters. [7][8][9] In certain Asian countries, a higher-thanexpected male:female ratio at birth is thought to be a product of sex discrimination fuelled by the preference for sons. This preference has been attributed to various economic and cultural factors, including provision of financial support in old age, the burden of dowry payments and worship duties in India, 10,11 patrilineal lineage in China and India, and the 1-child policy in China.…”