Professor Shanna Swan, an American epidemiologist, has been committed to studying the impact of the environment on human health for many years. Recently, she pointed out in her latest book “Countdown”,It is estimated that by 2045, the number of male sperm may be zero, which is mainly caused by the use of environmental pollutants in human daily necessities.
These polluting chemicals include:Phthalates and bisphenol A (BPA) in plastics, and perfluoroalkyl and polyfluoroalkyl substances in waterproof materials.
When human beings face this kind of fertility dilemma, most couples will need to rely on assisted reproductive technology to have offspring. At the same time, human beings are exposed to more and more chemicals in daily life, which will cause the size of male penis to shrink and shrink.
This kind of advanced prediction view urgently needs conclusive evidence to verify, but the current evidence is not sufficient, and further research and analysis are still needed.
Correlation does not equal causation
Epidemiologists have discovered subtle associations between diseases and potential pathogenic factors, such as lung cancer and smoking behavior. Their research cannot determine the cause of the disease-just because the two events are related does not mean it is One is the root cause that caused or triggered another event.
In March of this year, environmental activists published an article mentioning that “hormonal-disrupting chemicals are destroying human fertility”, but the specific causal relationship between the two has not been determined.
We have reason to believe that chemicals that affect the function of human hormones, such as bisphenol A and perfluoroalkyl substances, can affect the reproductive ability of men and women. This can be explained, but so far we still have no conclusive evidence.Selective report
In 2017, Shana and several colleagues published a detailed review research report, showingBetween 1973 and 2011, the number of sperm in men dropped significantly by 59.3%.
However, this review report is somewhat one-sided.The report only observed sperm decline in men in North America, Europe, Australia and New Zealand, and the test subjects did not involve the sperm quality status of men in South America, Asia or Africa.
When the researchers combined the data of male testers from all countries, they found that the sperm quality of previous men showed a downward trend, mainly for the study of men in “Western countries”. The number of subjects and participants in the study was based on Western countries. the Lord.
When conducting research,
avoid biased views as much as possible, but select bias (related to the way the research participants choose), publication bias (researchers tend to report only observations they think are meaningful), and the original research as the basis of the investigation Other limitations of this study may have a greater impact on the study.
Many studies from all over the world show that male sperm counts are on the decline, which is worrying. However, scientists have not yet fully understood the specific reasons for the decline in male sperm counts.
Currently, researchers attribute the cause to chemicals in the environment, while ignoring other important factors, such as chronic diseases, diet, and obesity.
In fact, the decrease in the number of male sperm is closely related to some living habits, and attention should be paid to improving fertility by improving these living habits.
Problems with extrapolation
From 1973 to 2011, the sperm count of the male population studied showed a linear decline. But at that time, just drawing a trend line through data does not prove that the trend line can be pushed forward to an earlier period and later to a later period. This hypothetical data trend that exists outside the observation range is unscientific.
we know,In the early 1940s, the number of sperm in men was about 113 million sperm per milliliter. Based on the data, it is inferred that the number of sperm in men will drop to zero in 2045, and there may also be deviations.
When you see the trend line of sperm count change and extend the time to describe it forward, you will find that the number of male sperm will continue to decrease in the future until it reduces to zero in 2045.
Obviously inferred data is unreasonable and unscientific, but according to the inference, men may not have natural fertility in the next 20 years, which means that families may not be able to have children in the future, humans will not be able to reproduce, and the population will continue to decline. It seems too exaggerated and unscientific.
Don’t be nervous, your penis will not shrink!
The research report that chemicals can cause male penis shrinkage is obviously a grandstanding “headline party”. In fact, there is only one study on 383 young men in the Veneto region of northeastern Italy. The study compares the size of the male penis to that of Shanna. The type of chemical that thinks the male sperm count declines is linked.
It is reported that there are varying degrees of perfluoroalkyl pollution in the Veneto region,Statistics show that the average penis length of 212 men living in areas with moderate or high perfluoroalkyl exposure was 8.6 cm, which was 10% shorter than 171 men (average length 9.7 cm) from areas not exposed to perfluoroalkyl groups. .
However, some of the conclusions of the study affect the reliability of the observation results and also affect whether we can extend it to other populations.
The men tested are grouped according to where they live rather than their place of birth. Since the size of the reproductive organs is determined before birth, the relationship between the environment of their mothers during pregnancy and the size of their penis is more It is more meaningful to analyze where they live. Some people may move from their place of birth to live in other areas, and some people live in other areas without a permanent home.
Due to decades of industrial pollution, men living in contaminated areas of Veneto are exposed to perfluoroalkyl groups very seriously. We are not clear about the potential impact of human exposure to pollutants on a larger scale. What is the relationship between ordinary pollutants (such as food plastic wrap)?
This study lacks specific details about the study subjects and measurement conditions.
Normally, we will exclude those test subjects with abnormal physical conditions, such as the presence of congenital developmental abnormalities. These test subjects will affect the conclusions of the study, but it is not clear yet. Whether such test subjects are included in the study, in addition, the researchers did not mention the variables that affect the measurement of the male penis, such as: room temperature, body posture, whether the penis is in an erect state, etc.
From a semantic point of view, “shrinking” of the male penis is a normal phenomenon. The penis is a spongy body composed of the hardest smooth muscle and connective tissue of the male body. It is a kind of erectile tissue, which will gradually shorten over time after erection.
At present, both individuals and groups,
researchers have not found any research reports or evidence that environmental pollution has caused male penis shortening. Current statistics show that male penis size has not shrunk in the past few decades.
Although environmental pollution is a very urgent problem, fortunately, there is evidence that the catastrophic collapse of human reproductive capacity and the consequent shortening of the penis are unlikely to occur.