each bringing something different to the mission.

28-year-old physician and scientist, Alice Hamilton, joined the cause in 1897.

Hamilton hailed from upper middle class roots in Fort Wayne, Indiana, and initially she didn't feel suited for settlement life.

- It was loud.

It was chaotic.

It was crazy.

9,000 visitors a week, doors open in the morning, closed late at night.

And a lot of the Hull House residents, they thrived in that environment.

For others like Alice Hamilton, it was more of a struggle.

- [Narrator] Eventually, Hamilton found her footing.

And in her 20 years at Hull House, she would become an unlikely blend of scientist and crusader.

- She was a thinker ahead of her times on social issues and an early proponent of public health and the importance of public health.

- [Narrator] Most immigrants in the 19th Ward couldn't afford to see a doctor, so Addams encouraged Hamilton to open a well baby clinic to treat the most vulnerable.

That's when some patients pleaded with her to help their husbands, factory workers who were getting sick from mysterious illnesses that left some severely disabled.

(machine pounding) (men shouting) - You had patients with wrist drop, which was a peripheral neuropathy where the nerves were impacted and the patients came in like this and they couldn't manipulate their fingers.

- [Narrator] Hamilton suspected lead poisoning was the culprit.

- [Peter] At a time when the industrial revolution was really taking off in this country, lead exposure was coming from a variety of sources.

- [Narrator] In 1910, Hamilton led a statewide study of lead poisoning, the first of its kind.

- [Peter] Her appointment allowed her access to workplaces with heavy lead exposures.

- [Narrator] Hamilton uncovered dozens of factory operations involving the use of lead, and nearly 600 cases of lead poisoning.

- She was able to identify the source of lead exposure and then trace it as the cause.

It caused sterility.

It caused birth defects in the next generation, and it caused hematologic abnormalities, which we now know also included cancer.

- [Narrator] Thanks to Hamilton's groundbreaking work, Illinois passed the first workers' compensation law in U.S. history.

One year later, the nation followed suit.

- [Peter] The state said, if you cause the disease, you need to be compensating the workers.

Now, that was precedent setting in this country.