▁in ▁August ▁through ▁October ▁ 2 0 0 8 , ▁found ▁that ▁the ▁concentr ations ▁of ▁materials ▁that ▁made ▁up ▁t ire ▁cr umb ▁were ▁below ▁levels ▁considered ▁harm ful . ▁In ▁addition , ▁the ▁overall ▁study ▁protocol ▁and ▁many ▁of ▁the ▁methods ▁were ▁found ▁to ▁be ▁appropriate ▁and ▁could ▁be ▁implemented ▁in ▁the ▁field . ▁ ▁The ▁study , ▁however , ▁did ▁note ▁that ▁due ▁to ▁its ▁limited ▁nature ▁and ▁the ▁large ▁divers ity ▁of ▁materials ▁used ▁to ▁make ▁t ire ▁cr umb , ▁no ▁definit ive ▁conclus ions ▁could ▁be ▁reached . ▁▁ ▁The ▁Office ▁of ▁Environment al ▁Health ▁Haz ard ▁Ass ess ment ▁of ▁the ▁California ▁Environment al ▁Prote ction ▁Agency ▁tested ▁skin ▁sens it ization ▁by ▁play ground ▁surfaces ▁made ▁of ▁rec yc led ▁t ires ▁and ▁found ▁no ▁sens it ization ▁observed ▁suggesting ▁that ▁these ▁surfaces ▁would ▁not ▁cause ▁skin ▁sens it ization ▁in ▁children , ▁nor ▁would ▁they ▁be ▁expected ▁to ▁el ic it ▁skin ▁reaction ▁in ▁children ▁already ▁sens it ized ▁to ▁late x . ▁▁ ▁Chem R isk , ▁Inc . ▁in ▁Pitts burgh ▁conducted ▁a ▁review ▁of ▁expos ure ▁to ▁rec yc led ▁t ire ▁rub ber ▁found ▁on ▁play ground s ▁and ▁synth etic ▁tur f ▁fields . ▁They ▁concluded ▁that ▁no ▁ad verse ▁human ▁health ▁or ▁e colog ical ▁health ▁effects ▁are ▁likely ▁to ▁result ▁from ▁these ▁benef icial ▁re uses ▁of ▁t ire ▁materials . ▁ ▁Although ▁rub ber ▁mul ch ▁is ▁generally ▁regarded ▁as ▁safe , ▁rec yc led ▁t