Thursday, July 27, 2017

Collapsing Human Sperm Count and the Future of Humanity



Is humanity in trouble?

If you haven't seen this study, you ought to take a look at it now:
Hagai Levine, Niels Jørgensen, Anderson Martino-Andrade, Jaime Mendiola, Dan Weksler-Derri, Irina Mindlis, Rachel Pinotti, and Shanna H. Swan (2017). Temporal trends in sperm count: a systematic review and meta-regression analysis. Human Reproduction Update, pp. 1–14, 2017. doi:10.1093/humupd/dmx022

ABSTRACT: There was a significant decline in SC between 1973 and 2011 among Unselected Western (−1.38; −2.02 to −0.74; P < 0.001) and among Fertile Western (−0.68; −1.31 to −0.05; P = 0.033), while no significant trends were seen among Unselected Other and Fertile Other. Among Unselected Western studies, the mean SC [SPERM CONCENTRATION] declined, on average, 1.4% per year with an overall decline of 52.4% between 1973 and 2011..

Trends for TSC [TOTAL SPERM COUNT) and SC were similar, with a steep decline among Unselected Western (−5.33 million/year, −7.56 to −3.11; P < 0.001), corresponding to an average decline in mean TSC of 1.6% per year and overall decline of 59.3%. Results changed minimally in multiple sensitivity analyses, and there was no statistical support for the use of a nonlinear model…

WIDER IMPLICATIONS: This comprehensive meta-regression analysis reports a significant decline in sperm counts (as measured by SC and TSC) between 1973 and 2011, driven by a 50–60% decline among men unselected by fertility from North America, Europe, Australia and New Zealand. Because of the significant public health implications of these results, research on the causes of this continuing decline is urgently needed….
This study was a META-ANALYSIS so it looked at the results of 7,500 empirical studies on sperm counts and therefore came to its conclusions based on evaluation of the results of those 7,500 studies.

Most, albeit not all, of those studies reviewed in this meta-analysis address people of European descent. The paper notes that relatively few fertility studies are available for people in the global south.

Here is an empirical study of declining sperm quality and count among Chinese men:
Chuan Huang, Baishun Li, Kongrong Xu, Dan Liu, Jing Hu, Yang Yang, HongChuan Nie, Liqing Fan, Wenbing Zhu, ( ). Decline in semen quality among 30,636 young Chinese men from 2001 to 2015Fertility and Sterility, 107(1), 83–88.e2 DOI: http://dx.doi.org/10.1016/j.fertnstert.2016.09.035
Patient(s)
A total of 30,636 young adult men who applied to be sperm donors at the Hunan Province Human Sperm Bank of China in 2001–2015 were included in the study.
Intervention(s)  Physical examination and analysis of blood and semen samples.  
Main Outcome Measure(s)

Semen parameters, such as semen volume, sperm concentration, total sperm count, progressively motile sperm count, sperm progressive motility, sperm morphology, and round cells.  
Result(s)

Many of the semen parameters showed a decreasing trend over the 15-year observation period. The sperm concentration and percentage of sperm with normal morphology decreased from 68 × 106/mL to 47 × 106/mL and from 31.8% to 10.8%, respectively. Although sperm progressive motility showed irregular variation, the progressively motile sperm count decreased from 34 × 106 to 21 × 106 over the 15-year period. Furthermore, the rate of qualified donors fell from 55.78% in 2001 to 17.80% in 2015, and the rate for 2015 was approximately threefold lower than the corresponding rates in 2001.  
Conclusion(s)

The semen quality among young Chinese men has declined over a period of 15 years, especially in terms of sperm concentration, total sperm count, sperm progressive motility, and normal morphology.
What is causing this alarming decline in human sperm quality and quantity?

There are no doubt multiple variables that impact sperm quality, ranging from "lifestyle" factors such as diet, stress, and smoking to environmental factors, such as pesticides and BPA.

What is strangely missing from the acknowledged lists of culprits responsible for our looming reproductive collapse are the toxic and radioactive elements that we have unleashed upon the earth including lead, arsenic, mercury, and radioactive isotopes, particularly those that bioaccumulate in the testes (such as plutonium) and that impact the endocrine system (such as radioiodine).

I've written extensively at my blog about the concerns of twentieth century scientists and physicians who studies the effects of ionizing radiation on reproduction. here are a couple of highly relevant samples:
https://majiasblog.blogspot.com/2012/05/burdening-species-with-genetic.html?m=0

http://majiasblog.blogspot.com.au/2012/06/systematic-study-in-first-bear-study-on.html#comment-form

http://majiasblog.blogspot.com/2013/05/bear-report-1956.html
These links address the 1956 Biological Effects of Atomic Radiation Report. The Genetics Subcommittee's contribution to this report outlined the potential for ionizing radiation to lead to sudden collapses in reproductive fitness due to accumulated germline cell damage.

Too much genetic and/or epigenetic damage to germline cells promises the collapse of our species.

I've previously posted about the potential relationship between exposure to ionizing radiation and de novo mutations linked with autism. Children with autism have been found to have more de novo mutations than parents and unaffected siblings.

What causes de novo mutations? Well, do novo mutations and epigenetic changes can be caused by myriad genotoxins but exposure ionizing radiation is among the most potent mutagens known.

The relationship between autism and ionizing radiation has not been studied, despite the sharp INCREASE IN AUTISM INCIDENTS in CA after Fukushima.

You can read more about the relationship I posit between autism and exposure to ionizing radiation here:

Majia's Blog: Autism and Exposure to Excess Ionizing Radiation: Is ... 
Majia's Blog: Autism and Radiation

Majia's Blog: Might Ionizing Radiation Contribute to Autism?

Majia's Blog: Ionizing Radiation and Our Neural System

Majia's Blog: Autism and the Environment: Let's Study Radiation

Majia's Blog: Ionizing Radiation and Germ Cell Damage: Link to Autism?

Majia's Blog: Living in a Radiation Contaminated Zone

Majia's Blog: Autism Conference and My Paper on the Ontology of ...

Majia's Blog: Chronic Radiation Exposure and Human Health
 

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