▁drink ing ▁water . ▁The ▁amount ▁of ▁al umin um ▁present ▁in ▁v acc ines ▁is ▁small , ▁less ▁than ▁ 1 ▁mill ig ram , ▁and ▁such ▁low ▁levels ▁are ▁not ▁believed ▁to ▁be ▁harm ful ▁to ▁human ▁health . ▁▁ ▁V acc ine ▁hes it ant ▁people ▁have ▁also ▁vo iced ▁strong ▁concerns ▁about ▁the ▁presence ▁of ▁formal de hy de ▁in ▁v acc ines . ▁F ormal de hy de ▁is ▁used ▁in ▁very ▁small ▁concentr ations ▁to ▁in activ ate ▁vir uses ▁and ▁b acter ial ▁to x ins ▁used ▁in ▁v acc ines . ▁Very ▁small ▁amounts ▁of ▁resid ual ▁formal de hy de ▁can ▁be ▁present ▁in ▁v acc ines ▁but ▁are ▁far ▁below ▁values ▁harm ful ▁to ▁human ▁health . ▁The ▁levels ▁present ▁in ▁v acc ines ▁are ▁min usc ule ▁when ▁compared ▁to ▁naturally - occ urr ing ▁levels ▁of ▁formal de hy de ▁in ▁the ▁human ▁body ▁and ▁pose ▁no ▁significant ▁risk ▁of ▁to x icity . ▁The ▁human ▁body ▁continu ously ▁produces ▁formal de hy de ▁naturally ▁and ▁contains ▁ 5 0 – 7 0 ▁times ▁the ▁greatest ▁amount ▁of ▁formal de hy de ▁present ▁in ▁any ▁v acc ine . ▁Furthermore , ▁the ▁human ▁body ▁is ▁capable ▁of ▁breaking ▁down ▁naturally ▁occurr ing ▁formal de hy de ▁as ▁well ▁as ▁the ▁small ▁amount ▁of ▁formal de hy de ▁present ▁in ▁v acc ines . ▁There ▁is ▁no ▁evidence ▁linking ▁the ▁inf re quent ▁expos ures ▁to ▁small ▁quantities ▁of ▁formal de hy