First, Wiesel et al. (2011) found that the birth defect rate of infants born from mothers who were occupationally exposed to radiation is significantly higher than those babies from the unexposed reference group. Mothers working with radiation dosimeter were exposed to ionizing radiation. Ionizing radiation is used in the medical industry to examine human bodies and treat diseases.
Researchers from Johannes Gutenberg University Mainz, Germany analyzed data on 3,816 infants who were born in south-west Germany between January 2007 and February 2008. 161 babies (4.3%) out of 3,787 reference group newborns whose mothers were not exposed to radiation showed birth defects. However, among 29 newborns whose mothers wore radiation dosimeter occupationally in the first trimester of pregnancy, four babies (13.8%) were born with defects.
Workers in nuclear power plants can be exposed to the same kind of radiation that the women working in the medical industry. Nuclear industry advocates may disagree with me. If so, how about the people exposed to radiation still being emitted from suspectedly at least partially melted-down six reactors of the Fukushima Dai-ichi (福島 第一) nuclear power plant in Japan? Since myths about nuclear power's safety are debunked now, nobody can tell future mothers that neighborhood nuclear power plants are safe for their pregnancy.
Second, radiation exposure causes abnormal sex ratios. Scherb and Voigt, researchers from German Research Center for Environmental Health investigated both time series birth data and compared sex ratios between babes born near nuclear power plants and those born in locations far from nuclear power plants.
Independent variables in this study are: presence of nuclear power plants within 35 km, atmospheric atomic bomb tests, and Chernobyl nuclear power plant accident.
Before introducing the results, I want to clarify the meaning of the term 'sex odds.'
[Sex Odds] = [male births]/[female births]
Sex odds is an indicator of reproductive health. Strikingly, this German study found statistically significant differences of sex odds between babies born areas (or times) affected by radiation and those from reference areas (or times).
(1) Effects of atmospheric radioactive fallout are not seen yet
From 1950 to 1963, sex odds decreased in both Europe and the USA.
Although atomic bomb tests were conducted during this period, its effects were not evident.
(2) Radioactive fallout due to atomic bomb tests
From 1964 to 1975, sex odds increased.
From 1976 to 1986, sex odds decreased again.
It was in 1963 when Partial Nuclear Test Ban Treaty went into effect. Before 1963, atomic bomb tests were conducted around the world. However their effects effects were observed after the treaty became in effect. The researchers assume radioactive fallouts were delayed.
(3) Radioactive fallout due to the Chernobyl nuclear power plant disaster
From 1987 to 2000, there was a upward shift in sex odds in Europe which is near Chernobyl.
From 1987 to 2002, sex odds decreased in the USA which is far from Chernobyl.
Another finding in this study is that sex odds of babies born within 35 km from German and Swiss nuclear power plants are higher than those born outside the radius area.
In sum, higher ratios of boys are born in times or areas that are affected by radiation from atomic bomb tests, nuclear disaster, or nearby nuclear power plants in normal operating conditions. It is not because more boys were born but because boy births were less decreased than girl births.
However, this study manifests that even low-level exposure to radioactive materials that have traveled long distance through atmosphere can cause genetic damages in people or survival rate changes in human embryos or fetuses.
My conclusions drawn from these two studies are simple.
If any parents want to have a healthy baby, they had better do two things:
(1) They have to live at least 35 km away from nuclear power plants.
(2) They have to live at least one continent away from possible nuclear tests or disasters.
Wiesel, A., Spix, C., Mergenthaler, A., & Queißer-Luft, A. (2011). Maternal occupational exposure to ionizing radiation and birth defects. Radiation and Environmental Biophysics. http://dx.doi.org/10.1007/s00411-010-0350-9
Scherb, H., & Voigt, K. (2011). The human sex odds at birth after the atmospheric atomic bomb tests, after Chernobyl, and in the vicinity of nuclear facilities. Environmental Science and Pollution Research. http://dx.doi.org/10.1007/s11356-011-0462-z
Nuclear and Industrial Safety Agency. (2011). Seismic Damage Information. Press Releases. Retrieved since March 12, 2011 from http://www.nisa.meti.go.jp/english/press/index.html