Previous studies have pointed out that exposure of parents to certain chemicals before the child is born may affect the sex ratio of the child born.The eco-chill survey started in 10, targeting 2010 pairs of parents and children nationwide, and is conducting follow-up surveys until the child turns 13 years old.Here, we used data from about 5 of these to examine the chemicals that fathers used at work before pregnancy and the relationship between their frequency and the sex ratio of the offspring.

　We asked their fathers to answer how often they used the 23 chemicals at work for more than half a day during the three months before their partner's pregnancy was discovered, and compared the gender percentages of the children born.As a result, it was found that the higher the frequency of pesticide use, the lower the proportion of boys born.This association was almost the same with statistical adjustments to other factors, such as the mother's use of chemicals.As for medical disinfectants, statistically significant results were obtained that the proportion of boys was low in the children of fathers who used them at least once a week.On the other hand, for mercury, radiation and other chemicals, no association was found between the frequency of use by the father and the sex ratio of the child born.

　In a birth cohort survey that tracks the period of growth before a child is born, such as the Ecochill survey, it is the book that reported the relationship between occupational exposure to chemicals in fathers and the sex ratio of offspring. This is my first time studying.However, since this study does not use objective indicators such as the concentration of chemical substances in blood, further accumulation of knowledge supporting this study is awaited.

Paper information:[The Lancet Planetary Health] Physical occupational exposure to chemicals and secondary sex ratio: results from the Japan Environment and Children's Study