Hospital employees often do not recognize the chemical hazards that exist in their work environment. 2. Formaldehyde and xylene are common hazards in histology and pathology laboratories. Occupational and environmental health nurses need to be familiar with the health effects that may result from exposure to these chemicals. 3. Although xylene does not have medical/health surveillance requirements set by OSHA, medical evaluation of employees exposed to xylene above the action level is effective occupational and environmental health practice. 4. Formaldehyde exposed employees require medical/health surveillance. Occupational and environmental health nurses need to be familiar with how to implement and manage a formaldehyde surveillance program.