Two contaminants, A and B$,$ are present in drinking water at concentrations of $0\mathrm{.}001$ mg$/$Land $0\mathrm{.}004$ mg$/$L$,$ respectively. The potency factors are $0\mathrm{.}2($mg$/$kg$/$day$)$ for A and $0\mathrm{.}1($mg$/$kg$/$day$)$ for B$.$ For an adult weighing $70$ kg and consuming $2$ L$/$day for $35$ years, calculate the lifetime cancer risk for each contaminant and identify which poses a higherrisk.