The number of spermatozoa among men in Europe, North America, Australia and New Zealand has decreased by more than 50% over the past 40 years, researchers said on Tuesday.
Analysts analyzed 7,500 studies conducted between 1973 and 2001. They selected 185 studies with consistent counting methods and performed data analyses of nearly 43,000 men.
Their findings, reported in the Human Reproduction Update, showed that sperm concentration increased from 99 million per milliliter to 47.1 million mL during the study period, indicating a 52.4% decrease in sperm concentration. The concentration of sperm And 59.3% in these countries. Also, the researchers found that the decrease in the number of sperm does not decrease. Since sperm controls have indices of morbidity and mortality, these results raise potential concerns for health and fertility.
Although previous screening of spermatozoa has been criticized for ignoring confounding variables such as age, sexual activity or infidelity, this research has used coherent methods of sperm screening and many Many data sets to address these concerns.
The review did not directly address the causes of the decline, although in the interviews with New Scientist, thinking of the creator Shanna Swan of the Icahn School of Medicine at Mount Sinai showed that since the decline of these countries, There might be a causal link with the chemicals. The impact of chemicals, such as phthalates, which are often found in food packaging and making their way into almost all brands of macaroni and cheese, has recently been questioned by data suggesting that they may interfere with Production of testosterone and endocrine systems.
Here is Kate Kelland, who reports to Scientific American:
“This study is an urgent awakening for researchers and health authorities around the world to investigate the causes of the sharp decline in sperm count,” said Hagai Levine, who co-led work at the Hebrew School – Hadassah Braun School of Public Health and Community Medicine in Jerusalem.
The analysis did not explore the reasons for the decline, but the researchers stated that the decline in the number of spermatozoa had already been linked to various factors such as exposure to certain chemicals and pesticides, smoking, stress, and obesity.
This suggests that measures of sperm quality can reflect the impact of modern life on male health and act as a “canary in the coal mine” that signals wider health risks, they said.
But not all the bad news – 47.1 million spermatozoa per milliliter is still well above the threshold of 15 million sperm that is considered low from the fertility point of view. The study did not reveal a clear decrease in the number of spermatozoa among men in South America, Asia or Africa, but the authors point out that fewer studies have been carried out in these regions. At the moment, the question of what causes the decline in sperm count remains open, but evidence of the trend is becoming more and more obvious.