What was the first type of drug known to be widely used in international competition and that led to the first olympic urine-testing programs?

The answer to the question above is steroids.
Steroids was the first type of drug to be widely used in international competition and that led to first olympic urine-testing program, which happened in 1970s. 2,000 people were tested; less than 300 of them has traces of steroids and only 8 came back as positive.

Farm land would be my guess