Fitch produces an ESG exposure score with elements rated on a scale of one-to-five where three is neutral in that a risk is minimally relevant or it is well-managed, and four and five are relevant to the credit risk.

"22% of the 1500 issuers we rate are affected by ESG issues, surprisingly not so much on environmental issues, but social and government," he said.

Investors are increasingly asking for ESG risk information to include in their investment decisions, particularly in light of disasters such as tailings dam failures.

For David Coombs, head of copper consulting at CRU, ESG-related risk exposure will change how major miners will divest assets going forward.

"The long standing practice of divesting near end-of-life assets to smaller companies is less likely to happen in the future as big companies become more concerned about their reputations in light of the Brazil tailings disasters. Going forward, they will increasingly hold onto them to ensure closure issues are properly managed," he said.