I recall litening to two 1 hour radio broadcast presentations by a public health MD (from memory I believe his name was Stuart Levy from the USA) . This was 5 to 10 years ago. But I do not think what he presented has changed very much in the US.
He reported that in the US cattle industry feeding cattle with estrogen is an permissible practice. The intention is to increase the weight of the cows which brings an increase of gross profit of about $140 per head (multiply that by over 30 millions of cows & you see the economic aspect which drives the cattle industry lobby).
Normally ,according to regulation, the estrogen should be injected in an ear of the cows to slow & limit the amount absorbed. But in many cases the drug is illegaly injected in other parts of the animals to increase absorption up to a point where the dose is 200 times higher (if my memory serves me right) .
At the time of the broadcast it was said that only 10 US federal inspectors were assigned to check observance of regulation accross the country which essentially means no enforcement.
The MD reported epidemiology studies comparing the rate of cancer incidence over 2 periods of time for breast cancer (before & after the introduction of estrogen use in cattle) for different age groups of women.
There was a strong correlation between incidence & estrogen in livestock.
Here is a more recent article on the same subject:
http://www.phschool.com/science/scie...ones_beef.html Hormones: Here's the Beef
Environmental concerns reemerge over steroids given to livestock