Guzelian raises a number of points in his letter and provides an alternative perspective on the documentation of causal relationships in chronic diseases. We will address the points, as we understand them, in the order in which he raised them in his letter.First, Guzelian implies that patient 1 was exposed only to a low amount of 1,1,1-trichloroethane (TCA). This is incorrect. The characterization of exposure as to 1/10th of the permissible exposure level by the employer's insurance company occurred after diagnosis of fatty liver disease was made. The workplace had been clearly modified after diagnosis of disease, and the patient's job had been abolished in its previous form. Therefore, no representative sampling for his prior exposures was or could be performed. It was, therefore, impossible to determine what level of exposure was associated with the development of disease. This was clearly stated in our article1
Hodgson MJ, VanThiel DH. 1,1,1-Trichloroethane and the Liver-Reply. Arch Intern Med. 1991;151(11):2322–2326. doi:10.1001/archinte.1991.00400110145036
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