Variables influencing the toxic response to organophosphates in humans.

Concerns and doubts associated with the predictable health effects in humans following exposure to xenobiotics is primarily due to the failure to consider the variables influencing the toxic response in each instance. Lack of correlation between laboratory data, animal experiments and clinical findings in man associated with exposure to organophosphates (OPs) is an example. We have reviewed the literature to identify the variables that need to be considered following exposure to OPs. These include factors related to the OP (physico-chemical properties, solvents, impurities), duration and routes of exposure, and factors related to the individual(s) exposed. Individual variables include variations in metabolic, sequestration and excretory processes and health status (age, gender, environmental factors, concurrent medications, cholinergic status). The assessment of ill-health following exposure is critical to the development and compliance with guidelines and to the adoption of the best instrumentation. We have suggested a schematic assessment that needs to be applied for each exposure associated with organophosphates and provided the reasons for the development of this format. Exposure to xenobiotics through the environment, occupation or following therapy is an unavoidable aspect of modern life. Application of the principles discussed to each xenobiotic exposure is necessary to provide accurate and adequate information to advance the prevention or minimising toxicity.