The risk of latex sensitization in children with spina bifida is related to recurrent mucus membrane exposure to water soluble natural rubber latex protein eluting off of urinary catheters. The amount water soluble of natural rubber latex protein that could possibly contact the mucous membranes of a child playing at a playground that has ground tire mulch would be extremely low, assuming the child was not ingesting or chewing on the mulch. There is no publication in PubMed that I could find on this issue.
I hope this information is helpful.
Eric Macy, MD, MS, FAAAAI