At JK Enterprises, we pride ourselves on our top-quality materials, and never more than with our playground mulch. Unlike landscaping mulches, playground mulches are meant to be played on and around, so it’s crucial that it is clean, free from debris and splinter resistant. Additionally, to be labelled “playground” mulch, it is required to be a “certified safety surface” which means, among other things, that it is firm underfoot (so as to be ADA accessible and not cause tumbles) and that it be cushiony enough for landing on if a fearless youngster should fall from the monkey bars. We’ve explained a bit more about playground mulches in another blog post.
But what about the other popular “certified safety surface” for playgrounds? That’s rubber mulch. Rubber mulch is popular for a few reasons. For one thing, it’s “recycling”. It’s made from the millions of tires that wear out every year and that tire companies would have to pay big bucks to dispose of. The very thing that makes it hard to dispose of is what schools and playgrounds like about it -- it doesn’t decompose. That means you never have to top it up as you have to periodically with wood mulches, which break down over time.
Now, we understand that not everyone wants to top up their wood mulch every year or two, but if that’s the case, try pea gravel. We don’t like rubber mulches and here’s why.
The Side Effects of Rubber Mulch
Let’s start with the least-scary reason; the environment. Rubber doesn’t really decompose. It’s kind of like plastic. It just sits there, getting weathered away like so many bottle caps. If the playground ever stops being a playground, the rubber “crumbs” will most likely get turned under the soil. That’s not recycling. That’s polluting. And they’re selling you the pollutants.
The other reason is much more scary. According to some, rubber mulch is not as inert as the marketing materials claim. Although the EPA okayed its use, the very limited study that they did (only two playgrounds) merely tested the risk of lead contamination. However, the Connecticut Agricultural Experiment Station reported “under relatively mild conditions of temperature and leaching solvent, components of crumb rubber produced from tires (i) volatilize into the vapor phase and (ii) are leached into water in contact with the crumbs.” (source)
Environment and Human Health, a Connecticut-based non-profit research agency, released a report saying, in part, “It is clear that the recycled rubber crumbs are not inert, nor is a high-temperature or severe solvent extraction needed to release metals, volatile organic compounds, or semi-volatile organic compounds. The release of airborne chemicals and dust is well established by the current information...Health endpoints of concern are numerous, including acute irritation of the lungs, skin, and eyes, and chronic irritation of the lung, skin, and eyes. Knowledge is somewhat limited about the effects of semi-volatile chemicals on the kidney, endocrine system, nervous system, cardiovascular system, immune system, developmental effects and the potential to induce cancers,” and that rubber mulch “may not be appropriate for playgrounds with open layers of recycled tire crumbs.”