Gutierrez v. Cassiar Mining Corp. (1998) 64 Cal. App. 4th 148, illustrates that the nature and extent of medical monitoring costs for which a defendant may be liable are very much dependent factors peculiar to the individual plaintiff. In that case, the plaintiff was seeking to recover the costs of future medical monitoring due to asbestos exposure. Evidence was introduced suggesting that all of the monitoring was already needed for preexisting conditions arising from plaintiff's smoking and exposure to tuberculosis. The appellate court held that the trial court erred in refusing to instruct the jury regarding the effect of preexisting conditions on an award of economic damages to cover the costs of future medical monitoring. Thus, we see that determining the right to medical monitoring in a class action is not a simple matter of showing that a certain number of people were exposed to toxic chemicals over a certain amount of time. The defendant's liability to pay for medical monitoring depends on an individual plaintiff's exposure, lifestyle, and any preexisting conditions.