See Shanna Swan and the Count Down book. This effect is already established, many of the mechanisms are established, science is discovering more mechanisms, but we already know enough to start taking public health actions.

The epi evidence is clear and the mechanisms behind several exposure like phthalates have been established in animal studies and human epidemiological studies.

notable are:

1. The question of declining sperm density revisited: an analysis of 101 studies published 1934-1996.

2. Environmental phthalate exposure in relation to reproductive outcomes and other health endpoints in humans