​ Chemicals and fossil fuels could be behind falling birth rates

​Alarming new international study published in the prestigious journal Nature Reviews Endocrinology. 

​Professors Anders Juul (left) and Niels Erik Skakkebæk are the main autors of the new study. 

Most of the low and falling birth rates in Denmark and the rest of the world are possibly linked to massive exposure to the chemical substances in almost all consumer products in modern society.

The birth rate is so low in all the industrialised part of the world that there is now a shortage of young people, and in just a few years, the total population will start falling. So far, explanations have primarily focused on cultural aspects. One of the most important has been the changing role of women in society, and that they postpone having children to concentrate on their education, finances and career. However, an international study from Rigshospitalet indicates a secondary and very alarming explanation.

- We have to face it; environmental factors are having a decisive and negative impact on our reproductive capacity, and the cultural explanations cannot stand alone. Semen quality in healthy Danish men is today much poorer than 50 years ago. We have also seen a significant increase in testicular cancer in Denmark and the rest of the world, says the main author of the study, Professor Niels Erik Skakkebæk from Rigshospitalet.​

A major societal problem

With the co-authors of the study, he points to the chemicals in our surroundings as the major culprit. 

- The foetus and children are particularly sensitive to chemical exposure, and this is a contributory factor to the significant increase in the number of congenital abnormalities of the male genital organs in infants, poorer semen quality in young men, and higher incidences of testicular cancer. Exposure could also be why more and more girls in particular reach puberty early, said one of the authors of the study, Professor Anders Juul from Rigshospitalet, and he continued:

- There’s no doubt that we’re facing a serious societal problem. Around one in ten Danish children are born today after assisted reproduction. And more than 20 per cent of men never have children. This cannot be explained genetically because the development has taken place over just a few generations. Therefore, it's extremely important that we examine more closely the relationship between infertility and environmental factors.

The problem started with industrialisation

The study suggests that the decreasing birth rates began at the same time as industrialisation and the start of large-scale burning of fossil fuels. The authors’ hypothesis is that fossil fuels are also major culprits behind the negative influence of chemicals on human reproductivity.

- Ten per cent of the entire global consumption of fossil fuels is currently used as ingredients in chemicals contained in more or less everything around us: Toys, clothes, cosmetics, food, packaging, building materials and so on. Many of the substances are endocrine disruptors, and we are massively exposed to these substances, which can also be traced in blood, urine, semen and amniotic fluid from the entire population, said Niels Erik Skakkebæk.

We must protect pregnant women better

The decreasing birth rates are behind a demographic development that has been a time bomb under society for decades, but we are only now seeing the impact. Over the past 50 years, too few children have been born in Denmark to reproduce the population. 

- In a few years, without a corresponding increase in immigration, we will see a decreasing population like that already seriously challenging the Japanese, said Niels Erik Skakkebæk.

The two professors say this could also become a major problem in Denmark.

- Today, there are fewer young people than there were 50 years ago, and we will simply become short of labour. This is already challenging the very foundation for our welfare society. Our modern lifestyle has a great influence on our ability to reproduce, and the most sensitive individuals are the foetus and children. Therefore, it is crucial that we better protect pregnant women against endocrine disruptors, and it is vital that the relationship between these chemicals and our ability to have children has top priority on the health agenda in Denmark and the rest of the world, stressed Anders Juul.

The study in brief

The study is from Rigshospitalet, but includes data from many countries and different research fields. Researchers have contributed from Denmark, Israel, Brazil, France, the UK and Australia. The main points include:
  • The drop in birth rates can be traced back to the early 1900s and may very well be related to the use of fossil fuels.
  • Since the 1970s, the Danish fertility rate has been less than 2.1 children per woman (rate necessary to maintain the population) while in the same period worldwide it has gone from around five to 2.5 children per woman.
  • Semen quality in Danish men is very low. On average, more than 90 per cent of all sperm cells in a sperm sample are deformed.
  • Ten per cent of all children in Denmark are today born after assisted reproduction, including IVF, ICSI and insemination, e.g. with donor.
  • The number of men with testicular cancer is increasing drastically throughout the Western world.

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