Sperm counts declining

Are sperm counts declining?

1. A 1992 study (by Elizabeth Carlson) analyzed 61 studies of semen quality covering 15,000 men among 23 different countries. From 1938 to 1991 the sperm count decline was 50% (113 million sperm to 66 million per ml). 
2. A 1995 French publication noted a 30% decline from 1970 to 1992 (89 to 60 million/ml).
3. Another study looked at French sperm counts from 1989 to 2005. It involved 26,000 men and counts dropped from 73.6 million to 49.9 million sperm/ml. Various factors were controlled for like socioeconomic status and age.

Summary
1938 count: 113 million sperm/ml
1970 count: 89 million
1989 count: 73.6 million
1991 count: 66 million
1992 count: 60 million
2005 count: 49.9 million

From 1938 to 2005 (67 years) levels dropped to 44% of 1938 levels.

Theories of cause include increased endocrine disruptors in our food and bodies (this includes Roundup and BPA and other phthalates), jobs where men sit for most of the day, and too many hot jacuzzi hot tubs.


Sources

1. Sherins, RJ, Delbes, G. Is there a decline in sperm counts in men? American Society of Andrology. 
2. “Decline in semen concentration and morphology in a sample of 26 609 men close to general population between 1989 and 2005 in France”, by M. Rolland, J. Le Moal, V. Wagner, D. Royère, and J. De Mouzon. Human Reproduction journal. doi:10.1093/humrep/des415. Link to abstract. 
3. Pacey, A. A. (2013). Are sperm counts declining? Or did we just change our spectacles? Asian Journal of Andrology, 15(2), 187–190. http://doi.org/10.1038/aja.2012.165. Link to full study. EPUB and PDF also available.