$(1)$ Suppose that a $3-$ month subchronic study was conducted in rats, the NOAEL and LOAEL for the styrene were $450$ mg$/$kg and $1100$ mg$/$kg body weight per day, respectively. If each of the adjustment factors is equal to $10,$ calculate the reference dose for this chemical. $(2)$ If an adult has drunk water from a well contaminated by styrene for $35$ years. The concentration of styrene in the groundwater is $3\mathrm{.}2$ mg$/$L and RfD value is referred from the previous question. Calculate the health risk of an adult for drinking the groundwater using the information below:

IR $=3\mathrm{.}2$ L$/$day$,$ EF$=335$ days$/365$ days, and BW$=80$ kg$.$