I was reading a Slate article about lead in children’s toys. In it, it says that lead paint is still commonly used for road markings and bridges.
Is this really true? Is this source of lead harmful to human health?
Those road markings and painted bridges eventually get degraded and the paint gets pulverized to dust. I would think that this would spread lead over a wide area and anyone in the vicinity would be at a great risk of lead poisoning, even those in cars. I ride my bicycle for thousands of kilometres each year on the road and this would really concern me if it could harm me.
What is the straight dope?
I didn’t even know road paint had lead in it. I look forward to the replies of those educated in this field.
While I can’t speak directly for the toxicity impacts of lead in road paint my suspicion would be that it is in such minute quantities that it would not impact people’s health too much. That said, there are concerns and attempts to reduce it. In Minnesota about 10-15 years ago the Department of Transportation changed the standards for yellow road paint to remove the lead. (Evidently lead was not used in the white paint.) This resulted in a change in color from bright yellow to a pale creamed-corn type of yellow. The paint suppliers have improved the mix now and the yellow paint is almost back to its former glory, but those first few years were a bit strange.
I don’t know about other parts of the country.
I also know that bridges and watertowers are now painted with unleaded paint. It is a problem when removing paint from old bridges and towers by sandblasting in preparation for repainting. They have to enclose the entire structure and collect all the paint dust for proper disposal, a procedure that adds a lot to the overall cost.
Short answer: Yes, lead in highway markings and bridge paint is very harmful to humans.
It’s a very significant problem for bridge workers but possibly not so much of a problem for highway stripe painters as those people are working with less paint in a far greater area (miles of road), and road striping is relatively automated and done from a distance, rather than the much more hands-on nature of bridge work which often involves working in fairly confined or even completely enclosed spaces.
The “old style” yellow paint was pigmented with Chrome Yellow, chemically known as lead chromate. Unfortunately, while it’s a vivid and durable yellow, it’s also described as “profoundly toxic” as another component of the pigment is hexavalent chromium.
As long as you’re not spending a lot of time licking the centerline, the lead paint on roads probably won’t harm you very much. The problem with lead paint in houses and lead paint on toys, is that it flakes off or turns to dust, and then, because small children eventually put everything in their mouth, gets swallowed (and children are much more susceptible to lead problems).
As mentioned, the lead paint on bridges is a concern for workers (I know someone who worked on some bridge demolition/reconstruction projects; the company paid for regular lead tests for all the workers), and for neighbors (containment and proper disposal is often called for).