Hello,
There are no carcinogens as such in Glister toothpaste. Chemist must be referring to fluoride as carcinogenic but then most of the toothpastes have it and many studies on Google search have shown that it is carcinogenic but till now no proven study which is authentic have shown carcinogenic effect from toothpaste.
He must have denied it also as it is an amway product and other than always members it can't be sold.
Next Steps
u can use glister. There is no issue.
either buy from Amazon or some amway dealer.
Health Tips
you can go through other toothpastes too like colgate total or oral b prohealth tooth paste.