Applications of Toxicological Principles

APPLICATIONS OF TOXICOLOGICAL PRINCIPLES

Health professionals may be asked to provide an opin-ion of the cause and effect relationship between expo-sure to a xenobiotic and an adverse health effect rang-ing from symptoms of toxicity to death. Certain principles, including an assessment of temporality, should be considered in such an evaluation. Do the symptoms or disease follow the exposure within a proper time frame? In addition, an evaluation of the toxicological properties of the substance should be in-cluded. Does the xenobiotic possess properties that can logically be expected to cause the damage or disease in question? For many chemicals, the qualitative consider-ation of the types of symptoms, injury, or disease that may occur after exposure can be predicted based on the available toxicological data or known biological activity of the chemicals. If the toxicity or disease does not fit into this known profile, a causal relationship between the chemical and the problem should be questioned fur-ther. If the xenobiotic has the appropriate toxicological properties, quantitative consideration of the total dose received must be carefully evaluated. Was the dose high enough to produce health effects? Finally, the possibil-ity of alternate causes of the health problems must be investigated carefully. Are there other more logical ex-planations for the symptoms? If appropriate, drug side effects should be considered as a possible cause of the adverse health effects. Lifestyle and avocations also must be evaluated. Alternate causation is ideally evalu-ated by a thorough and frequently tedious review of complete medical, occupational, and social records of the patient.