There was an article in The Economist about this as well[0], which points out something that most other sources I've seen seemed to have skipped over:
"...much of the effect could be caused by changes in how sperm quality is measured.. the World Health Organisation’s manual on the subject has been revised four times since it was first published in 1980..."
"...a continuing investigation of Danish conscripts, is notable for having been established with a consistent method of measurement from the start. Its data show no changes over the years. And Dr Rolland and Dr le Moal admit that, despite the apparent drop in sperm counts they found, there was no increase in the number of infertile men during the period of their study."
I haven't actually dived into this new study to see if the authors accounted for these factors. Even if they did, it seems odd that the one study which has maintained the same method of measurement is the one that shows no changes.
Those revisions have actually enabled the problem to stay hidden longer; they've reduced the sperm count threshold at which men are considered "normal". You may be referring to technical issues, such as distinguishing live from dead sperm, or measuring motility---but WHO numbers don't reflect that.
"...much of the effect could be caused by changes in how sperm quality is measured.. the World Health Organisation’s manual on the subject has been revised four times since it was first published in 1980..."
"...a continuing investigation of Danish conscripts, is notable for having been established with a consistent method of measurement from the start. Its data show no changes over the years. And Dr Rolland and Dr le Moal admit that, despite the apparent drop in sperm counts they found, there was no increase in the number of infertile men during the period of their study."
I haven't actually dived into this new study to see if the authors accounted for these factors. Even if they did, it seems odd that the one study which has maintained the same method of measurement is the one that shows no changes.
[0] http://www.economist.com/news/science-and-technology/2156787...