Environmental experts have studied artificial grass installations for negative health effects. Most of them agree that the artificial grass are safe for children and adults alike to play on. But the jury is still out. Most of the studies that have been done were not comprehensive enough to say unequivocally that artificial grass crumb rubber infills are bad for human beings to be in contact with. The only way to say for sure is to do more tests.
Official organizations like the Synthetic Turf Council claim that there are no bad side effects from playing on an artificial grass field with crumb rubber infills; and other artificial grass companies claim likewise. But the conflict of interest of these companies and their claims of crumb rubber's harmlessness leaves many skeptical. More are pushing for crumb rubber's ban if tests cannot be completed.
The main obstacle preventing more thorough tests from being completed is that testing is very expensive, more expensive than most companies are willing to dish out, especially for something that could result in evidence which might be harmful to their business.
Other companies with a conflict of interest propose hiring a disinterested third party to conduct the tests so that artificial grass can be absolved in this crumb rubber controversy.