The primary goal of a company's product hazard assessment and communication program is to protect the health of its employees and customers. As litigation and government regulatory activity concerning product hazard identification and communication have increased, product hazard programs have become more sophisticated and complex. Hazard assessment has evolved from determination of acute toxic effects resulting from a single exposure to more complex assessment of effects from long-term, low level exposure. The evaluation of data and qualitative and quantitative extrapolation from animals to humans can be difficult. Pharmacokinetic data on interspecies similarities or differences can enhance the reliability of extrapolation. Communication of known or potential health effects to the employee and the customer is the key to ensuring safe use of the product and is accomplished by labeling the product container and by the Material Safety Data Sheet.