Section 120C. No insurer, agent or broker authorized to issue policies on the lives of persons in the commonwealth shall cancel, refuse to issue or renew, charge any excessive rates or restrict any length of coverage or in any way practice discrimination against persons primarily because the insured person has had a suspected, alleged or confirmed exposure to the potential hazards and afflictions of diethylstilbestrol or compounds commonly referred to as DES. The practices prohibited under this section shall include not only those overtly discriminatory but also practices and devices which are fair in form but discriminatory in practice.