Many people were becoming sickly after consuming American packaged meat and it got to the point where foreign governments were going to ban American meat imports. These issues were caused by poorly ventilated slaughterhouses that were ridden with many diseases that were included with the shipping of meat.
To combat widespread sickness and prevent a ban on American meat imports, Roosevelt understood that he had to take action. In order to combat these issues, he passed the Meat Inspection act of 1906. This ensured that meat shipped over state lines would be inspected upon being shipped. Many large shipping companies that shipped via train took the opportunity to drive their fly by night competitors out of business because it was easier to get the government's seal of approval. Soon after, he passed the Pure Food and Drug Act in the same year to accompany the previous act by prohibiting the sale of mislabeled food and pharmaceuticals.
As president, Roosevelt was a key person that attributed to passing these acts.
The Pure Food and Drug Act remained strong for a duration of 5 years until a loophole in the Pure Food and Drug Act was discovered when the Supreme Court ruled in U.S. v. Johnson states that the 1906 Food and Drugs Act does not prohibit false therapeutic claims, but only false and misleading statements about the ingredients or identity of a drug. This was quickly combated in 1912 when Congress enacted the Sherley Amendment to overcome the ruling in U.S. v. Johnson. The Sherley Amendment provided language that prohibited the intentional labeling of medication bottles or packaging with false therapeutic claims. Since then, there have only been minor additions or subtractions simply due to the passage of time. Overall, I believe that these acts were highly effective because they prevented much disease and prevented poisonous products from affecting more people than it already did.