A reader recently asked me to look into a playground mulch product to determine its toxicity.  I’d like to share the results with you because I think it will be helpful to anyone trying to decide what material to use for their outdoor playsets but also because it is a good example of how important it is to look beyond marketing claims and understand what regulations do and do not address.

The product is described as a virgin rubber mulch product that contains no phthalates, heavy metals or VOCs.  It meets California indoor air standards.  The company distinguishes its product from tire-derived rubber (TDR) that is often used on playgrounds and turf fields and has been found to emit dangerous levels of chemicals as well lead.

The company is unable to provide a Safety Data Sheet (SDS) because it is made from trimmings and unused material from children’s safety tile flooring.  Their product is a combination of products from many different manufacturers.

They were able to provide testing that showed that the test sample had:

• No detectable levels of phthalates. This is not surprising because while phthalates were widely used in flooring, manufacturers have been eliminating them.
• Lead detected at 3ppm which is well below California’s restriction of <80ppm for playground mulch but it is not zero.

There was no testing done for Total VOCs (TVOC) but if the product meets California Section 01350 it must have TVOC less than or equal to 0.5mg/m³.

Here are my concerns that this product, while perhaps not as bad a tire-derived rubber, has some of the same issues:

VOCs

• A  2010 study by California’s Department of Public Health (CDPH) titled Tire-Derived Rubber (TDR) Flooring Chemical Emissions Study found:

• • Both TDR and new rubber (NR) flooring products still emit a myriad of VOC chemicals, and their release is not uniform among the different products. A minority of products released excessive amounts of chemicals; and
  • Xylene, butylated hydroxytoluene, ethylbenzene, toluene, formaldehyde and acetaldehyde were found in a range of products. Benzene and carbon disulfide were above the health threshold in one or two samples… Some of the identified chemicals do not yet have health-based standards, making their health impacts difficult to assess.

Even if the product meets California Standards, it is likely emitting at least some of the above chemicals, just at a level that meets the standard.  Because this will be outdoors, the risk is somewhat mitigated (although it’s still not good for the environment!).

Lead

There is a level of lead, it is simply below the standard allowed.  California has a restriction of 80ppm for rubber mulch used on playgrounds.  While no level of lead is safe, some soil can contain levels of lead that are higher.  The EPA considers 400ppm in soil acceptable.  But, again, no level is safe.

The limitations of the testing provided is that it is unclear how much of the finished product is actually tested.  Because the product is a combination of materials from many manufacturers, it is not known if the test covers products from every supplier or is it a test of just one or a few.  Given the potential problems with new virgin rubber it is a concern.

Overall, this product is likely much less toxic than tire-derived rubber mulch.  It does, however, have low levels of lead and VOCs.  The VOCs will be mitigated because it will be outdoors.  While this is a less toxic product, I would still opt for natural, untreated wood mulch.