Charge quantization in a chiral bilepton gauge model
  In the context of the standard model the quantization of the electric charge occurs only family by family. When we consider the three families together with massless neutrinos the electric charge is not quantized any more. Here we show that a chiral bilepton gauge model based on the gauge group SU(3)_C X SU(3)_L X U(1)_N explains the quantization of the electric charge when we take into account the three families of fermions. This result does not depend on the neutrino masses. Charge quantization occurs either the neutrinos are massless or Dirac or Majorana massive fields. 
C.A de S. Pires and O.P. Ravinez