 Safety Margin A safety margin is the factor that is added to account for uncertainties. For example, if a chronic test in fish showed no effects at 00μg/L, an assessment factor of 00 is still added, meaning that the acceptable concentration in water would be only 0μg/L. Safety factors in environmental risk assessments vary depending on area and test system, and are typically higher for the assessment of acute effects than for chronic effects. VIEW FULL GLOSSARY 