Bruhat Bengaluru Mahanagara Palike [BBMP] — harmful ink being used for home quarantine stamping

My 69 year old parents travelled to bangalore by ai flight 775 on aug 14th 2020. On arrival, they were stamped on their hands for home quarantine. The ink used, is so harmful that my parents’ skin are burnt and swollen with pain. I complained to dipr as advised by airport authority and they just sent me phone no for medical helpline. The material needs to be teated and approved for human application.