Where's the crumb rubber?

Good to see that the Examiner is still asking questions about the stuff the city is using in city parks (Rec and Park exposing children to potentially cancerous material).

From Robyn Purchia's op-ed:

For years, city officials have assured San Francisco that it’s safe for kids to play on ground-up, used tires. But a cancer cluster linked to tire fields in Washington and a lack of comprehensive studies has federal and state agencies concerned. Although these agencies have commissioned more studies, our local government keeps touting the health benefits of playing on tires.

Shouldn’t The City at least let us know where it put the potentially carcinogenic material?

In some parks, like South Sunset and Silver Terrace, the ubiquitous black pellets are obvious. But sometimes it’s not. Concerned parents around The City have asked me if the rubber padding in their kid’s football field or the playground where their toddler plays is made from ground-up tires, also known as crumb rubber...

Previous posts on the issue here, here, and here.