Sorry, my last quote source was from Manitoba government Agriculture, Food and Rural Initiatives publication on food safety (not the Canadian gov't). Here is another section:

Hormones Increase Beef Quality
Hormones are produced naturally by all plants and animals including humans. Growth promotants contain estrogen-like hormones which add to the animal's own natural hormone production. The hormones increase beef quality by directing growth towards muscle and away from fat, allowing feed to be converted more efficiently to meat.

Hormone implants are placed under the skin of the ear, an inedible part of the carcass. The pellets dissolve slowly over a period of time and add to the amount of hormone naturally present. There is no need to be concerned about hormone residues in meat as only tiny quantities remain. For example, a 100 gram (3½ oz.) serving of steak from a steer treated with growth hormones contains about 1.9 nanograms of estrogen. (A nanogram is one-billionth of a gram.) The same amount of steak from an untreated steer contains 1.2 nanograms - a difference of only 0.7 billionth of a gram! Compare this to a 100 gram (3½ oz.) serving of cabbage which can contain up to 2,400 nanograms of naturally occurring estrogen, 1200 times more than that serving of beef.

Synthetic growth hormones are not allowed to be used in raising hogs, poultry and dairy animals. However, these animals do contain natural estrogen (as do some vegetables).

Antibiotics Help Sick Animals and Protect Consumers
Antibiotics are permitted for use in cattle, pork and poultry production:
•To treat sick animals and birds
•To control and/or to prevent disease during times of stress
•To promote increased feed efficiency or growth rates
Consumers have voiced concern, that people who are allergic to antibiotics and sulfa drugs may be exposed to them from residue in food. There is also concern that the use of these drugs at low doses creates drug-resistant food-borne bacteria, thus making bacterial food poisoning more difficult to treat.

In actual fact, allergic reaction from residues in food is rare and all food-borne bacteria are killed by adequate cooking, whether they are resistant to antibiotics or not.

Facts About Food Safety