▁ph osph orus ▁will ▁be ▁exha usted ▁within ▁the ▁next ▁ 1 0 0 ▁years ▁at ▁current ▁rates ▁of ▁usage . ▁Without ▁mechan isms ▁such ▁as ▁tax es ▁or ▁subs id ies ▁to ▁internal ize ▁external ities , ▁business es ▁may ▁ignore ▁them ▁despite ▁the ▁costs ▁im posed ▁on ▁society . ▁To ▁make ▁such ▁non f is cal ▁benefits ▁econom ically ▁relevant , ▁advoc ates ▁have ▁pushed ▁for ▁legisl ative ▁action ▁to ▁increase ▁the ▁demand ▁for ▁rec yc led ▁materials . ▁The ▁United ▁States ▁Environment al ▁Prote ction ▁Agency ▁( E PA ) ▁has ▁concluded ▁in ▁favor ▁of ▁rec y cling , ▁saying ▁that ▁rec y cling ▁efforts ▁reduced ▁the ▁country ' s ▁carbon ▁em issions ▁by ▁a ▁net ▁ 4 9 ▁million ▁metric ▁t onnes ▁in ▁ 2 0 0 5 . ▁In ▁the ▁United ▁Kingdom , ▁the ▁W aste ▁and ▁Resources ▁Action ▁Program me ▁stated ▁that ▁Great ▁Britain ' s ▁rec y cling ▁efforts ▁reduce ▁CO 2 ▁em issions ▁by ▁ 1 0 – 1 5 ▁million ▁t onnes ▁a ▁year . ▁Rec y cling ▁is ▁more ▁efficient ▁in ▁dens ely ▁populated ▁areas , ▁as ▁there ▁are ▁econom ies ▁of ▁scale ▁involved . ▁ ▁C ertain ▁requirements ▁must ▁be ▁met ▁for ▁rec y cling ▁to ▁be ▁econom ically ▁feas ible ▁and ▁environment ally ▁effective . ▁These ▁include ▁an ▁ade qu ate ▁source ▁of ▁rec y cl ates , ▁a ▁system ▁to ▁extract ▁those ▁rec y cl ates ▁from ▁the ▁waste ▁stream , ▁a ▁nearby ▁factory ▁capable ▁of ▁re processing ▁the ▁rec