Before actually talking about it, let’s make it clear, what are parabens? They are a group of preservatives that can be obtained naturally from fruits like blueberries, or they can also be synthesized artificially, they protect products from microbes, fungus and bacterias.
Between 70-90% of beauty and pharmaceutical products contain it. Authorities consider these products low in toxicity that body can absorb and eliminate fast when consumed internally and when they are from natural origin it is not the same when they are synthesized and overused.
An Edinburgh University run a reseach in 2004 with carcinogenic tissues on breast cancer patients where parabens were to be discovered; there the controversy came out, and it has not been denied or fed by other research. Though some scientist believe that parabens imitate estrogens making them responsibles for the tumors.
As it happens with these and other additives, the overuse of products that contain them disables body’s possibility to eliminate them. So let's not overuse them.