  We analyze the electronic properties of adatom doped graphene in the low
impurity concentration regime. We focus on the Anderson localized regime and
calculate the localization length ($\xi$) as a function of the electron doping
and an external magnetic field. The impurity states hybridize with carbon's
$p_z$ states and form a partially filled band close to the Dirac point. Near
the impurity band center, the chiral symmetry of the system's effective
Hamiltonian is partially preserved which leads to a large enhancement of $\xi$.
The sensitivity of transport properties, namely Mott's variable range hopping
scale $T_0$, to an external magnetic field perpendicular to the graphene sheet
leads to a colossal magnetoresistance effect, as observed in recent
experiments.
