There are studies of cell cultures, laboratory animals, wildlife, and accidentally exposed humans that show that environmental chemicals cause a wide range of reproductive, developmental, growth, and behavior effects, and so while "endocrine disruption in humans by pollutant chemicals remains largely undemonstrated, the underlying science is sound and the potential for such effects is real."  While compounds that produce estrogenic, androgenic, antiandrogenic, and antithyroid actions have been studied, less is known about interactions with other hormones.
They are g2g for sure. I've used Tren enanthate, testosterone enanthate, sustanon and clenbuterol from Alpha Pharma. Gains with the injectable steroids were really great. Nothing to complain about and almost no pip (all ampoules). However the clen (Astralean 40 mcg) I used was really underdosed, perhaps a bad batch or something. I had to take 4 pills at once to feel something. With other clens My hands were shaking with only 2 pills of 20 mcg. They also have a site to check if the products you have are legit or not. They all have a nice seal above their serial numbers