Pure. Healthy. Modern.

Today, you might see those words on a product in a natural foods store or an upscale juice bar. But in the early 20th century, they were used to describe lead. Cheap and durable, lead was ubiquitous in everything from paint to gasoline to plumbing.

But though the dangers of lead poisoning were known in the United States, regulation lagged for decades. Meanwhile, lead poisoning became a public health crisis.

When humans breathe, eat, drink or touch traces of lead, it builds up in their bodies. Over time, the toxic metal can cause nerve disorders, create developmental delays, increase blood pressure, cause infertility and affect every organ. It took a concerted effort by concerned citizens to turn the tide on lead.

This Lead Is Killing Us,” an online exhibition from the U.S. National Library of Medicine, tells the stories of activists who mobilized against lead exposure.

The exhibition features images of industrial workers, public housing residents, physicians and others who agitated for change. There are also vintage advertisements that convinced people lead was a desirable addition to their homes.

“Lead helps to guard your health,” crows a 1923 advertisement for Dutch Boy Paints produced by the National Lead Co. Of course, it did anything but. (The company later changed its name to NL Industries, and Sherwin-Williams acquired Dutch Boy in 1980, just after lead was banned in house paint.)

Activists helped usher in modern lead regulations, and between 1976 and 2016, the median concentration of lead in the blood of 1- to 5-year-olds decreased 95 percent.

But people still get lead poisoning. These days, the most vulnerable groups are children under 6, pregnant women, refugees, workers and children who have been adopted internationally.

You can view the exhibition at bit.ly/NLMlead.