C????n? ??ld ?n the street ?? ??mm?nl? m?x?d w?th nearby ?n??th?t???, ??rn?t?r?h, ?u?n?n?, ?r ?ug?r, which ??n r??ult in ?dd?t??n?l t?x???t?. C????n? ?? ?dd??t?v? du? t? ?t? ?ff??t on th? r?w?rd pathway ?n th? brain. Following a ?h?rt ??r??d of u??, th?r? can be a h?gh danger that