Human sex ratio at birth and residential proximity to nuclear facilities in France

The secondary sex ratio in Italy over the past eighty years (1940 to 2019) and potential impact of radiological contamination after atmospheric nuclear testing and after Chernobyl: Temporal change-point analysis using Markov Chain Monte Carlo

In Europe, the male to female ratio at birth (secondary sex ratio: SSR; sex odds: SO) is 1.04-1.06, is influenced by many factors and is declining in industrialized countries. This study was carried out to identify possible impacts of fallout by atomic bomb tests or by the Chernobyl event on SSR in Italy. Italy is a country without commercial nuclear power generation for the last four decades and thus nearly free of radiological confounders. Counts of annual male and female live births in Italy are provided by the World Health Organization (WHO) and by the Italian Istituto Nazionale di Statistica (ISTAT). This study included 57.7 million live births (1940-2019) with overall SSR 1.05829. The Italian SSR trend was modelled with linear and non-linear logistic regression. Trend changes, i.e., periods with level shifts were estimated with Markov Chain Monte Carlo (MCMC). Two distinct idealized level shifts were identified superimposed on a uniform secular downward trend. The first one is seen towards the end of the 1960s with a jump sex odds ratio (SOR) 1.00681, p < 0.0001. The second one occurred in 1987 with SOR 1.00474, p < 0.0001. In each of the 3 periods separated by the two jumps, SSR uniformly decreased with trend SOR per 100 years of 0.98549, p < 0.0001. In conclusion, the secular trend in the Italian SSR showed two marked level shifts, at the end of the 1960s and from 1987 onward. These follow the release of radioactivity by atmospheric atomic bomb tests during the 1960s and by Chernobyl in 1986 and corroborate the hypothesis that ionizing radiation increases SSR.

Trends in births and the birth sex ratio in the vicinity of the Mainz research reactor in Germany

INTRODUCTION

The human sex ratio or sex odds at birth (M/F) are influenced by many factors. Radiation is the only stressor known to elevate the ratio while dropping total births. The Mainz research nuclear reactor (FRMZ) underwent extensive refurbishment commencing in 1992 and with further upgrading in 2011. This study was carried out in order to investigate any possible effects of these events on M/F.

METHODS

Annual municipality-specific births by sex were obtained from official government sources. Statistical methods used included ordinary linear logistic regression and Poisson regression.

RESULTS

M/F rose significantly in 1993 only close to the FRMZ (<10 km) with sex odds ratio (SOR) 1.023 (p = 0.0074) and this rise was associated with numerically equivalent drops in male births of 4.01% (p = 0.0251) and female births of 6.17% (p = 0.0005). No such effects were seen beyond 10 km.

DISCUSSION

These findings add to the corpus of evidence that man-made radiation may have significant effects on total births and on M/F with a skew toward male births. While the authors are certain that suitable precautions were taken when the reactor in Mainz was handled, the findings imply that these may not have been sufficient. Perhaps even greater care and even more stringent precautions need to be employed when dealing with radioactive elements. It clearly behoves humanity to exercise extreme caution when handling, processing, and storing radioactive materials and waste.

A systematic search of the factors that influence the sex ratio at birth

INTRODUCTION

The sex ratio at birth has been studied for decades. A systematic review of the factors that influence this has never been performed. This study conducted a systematic search of this topic.

METHODS

A scoping review of the literature was initially carried out in January 2012 and this was formally updated for contemporaneity in December 2017. A systematic search of the literature subsequently followed in May 2019 and was conducted based on PRISMA statement's flow diagram. The search was applied across five databases: Cumulative Index to Nursing and Allied Health Literature (CINAHL), MEDLINE, PubMed, The Cochrane Library and Web of Science and was restricted to January 1, 1990 to May 31, 2019. The systematic review stopped at screening stage of the PRISMA. A narrative approach was adopted to report study findings.

RESULTS

494 studies were included. Ten factors were identified from the literature as having an influence on M/F, with stress and sex-selective termination being the most predominant. Additional factors included the hormonal theory, geographical trends, coital rates, radiation, secular trends, seasonality and theoretical modeling.

DISCUSSION

Future studies addressing M/F should adopt similar methodologies in order to provide the possibility of comparison between findings and a more formal form of systematic review.

Increases in perinatal mortality in prefectures contaminated by the Fukushima nuclear power plant accident in Japan: A spatially stratified longitudinal study

Descriptive observational studies showed upward jumps in secular European perinatal mortality trends after Chernobyl. The question arises whether the Fukushima nuclear power plant accident entailed similar phenomena in Japan. For 47 prefectures representing 15.2 million births from 2001 to 2014, the Japanese government provides monthly statistics on 69,171 cases of perinatal death of the fetus or the newborn after 22 weeks of pregnancy to 7 days after birth. Employing change-point methodology for detecting alterations in longitudinal data, we analyzed time trends in perinatal mortality in the Japanese prefectures stratified by exposure to estimate and test potential increases in perinatal death proportions after Fukushima possibly associated with the earthquake, the tsunami, or the estimated radiation exposure. Areas with moderate to high levels of radiation were compared with less exposed and unaffected areas, as were highly contaminated areas hit versus untroubled by the earthquake and the tsunami. Ten months after the earthquake and tsunami and the subsequent nuclear accident, perinatal mortality in 6 severely contaminated prefectures jumped up from January 2012 onward: jump odds ratio 1.156; 95% confidence interval (1.061, 1.259), P-value 0.0009. There were slight increases in areas with moderate levels of contamination and no increases in the rest of Japan. In severely contaminated areas, the increases of perinatal mortality 10 months after Fukushima were essentially independent of the numbers of dead and missing due to the earthquake and the tsunami. Perinatal mortality in areas contaminated with radioactive substances started to increase 10 months after the nuclear accident relative to the prevailing and stable secular downward trend. These results are consistent with findings in Europe after Chernobyl. Since observational studies as the one presented here may suggest but cannot prove causality because of unknown and uncontrolled factors or confounders, intensified research in various scientific disciplines is urgently needed to better qualify and quantify the association of natural and artificial environmental radiation with detrimental genetic health effects at the population level.

The sex ratio at birth in France was unchanged 9months after the 1998 FIFA World Cup

INTRODUCTION

Positive psychological phenomena such as increased feelings of belonging linked to hosting the FIFA World Cup were observed in France 1998 and South Africa 2010. Approximately nine months after South Africa hosted the 2010 World Cup the sex ratio at birth increased significantly. Given the similarity of positive psychological phenomena between the two countries, this study sought to determine if the sex ratio at birth increased in France circa nine months after the 1998 World Cup.

METHODS

Anonymized publicly available live birth data from 1994 to 2004 inclusive was obtained from the Insee (Institut National de la Statistique et des Etudes/Économiques - National Institute of Statistics and Economic Studies). For statistical analysis, chi-squared tests were used.

RESULTS

The sex ratio at birth for March and April 1999 did not differ significantly from that of the rest of same period from 1996 to 2000 (p=0.558), there was also no significant difference for February and March 1999.

CONCLUSION

The sex ratio at birth did not increase in France after it hosted the 1998 World Cup. Possible reasons why the sex ratio at birth did not increase as it did in South Africa include a higher French prevalence of modern contraceptive use and a different kind/level of excitement for the World Cup in France since it has previously hosted large international sports tournaments. The influence of the World Cup on the sex ratio at birth depends on the context of a specific country.