The two crossword solutions for the term 'prefix with hazard' are ECO and BIO. ECO stands for 'ecology, ' which is the study of the interactions between organisms and their environment. BIO stands for 'BIOLOGICAL, ' which is the study of living organisms and their relationship to each other and their environment. Both ECO and BIO are prefixes that can be used to describe a hazard, such as an environmental or BIOLOGICAL hazard.