when combined effect is much greater than the sum of the effects of each given alone
synergistic
process to evaluate the potential for adverse health or environmental effects from exposure to naturally occuring or synthetic agents; includes estimate of probability of harm and description of assumptions and uncertainties that go into it
Risk Assessment
receptor expression repression
reduced responsiveness
they work to set levels for safe exposures to: environmental contaminants, food additives, medicinals
Regulatory toxicology
agent that can cause a deleterious response in a biological system