In this manner, it is possible to rank carcinogenic substances in order of priority for remedial action. EPI rankings indicate the relative urgency of dealing with different toxic substances. Determining whether a substance is toxic and estimating its EPI concludes the strictly scientific, or risk assessment, phase of the Priority Substances program. Health Canada and Environment Canada, in consultation with stakeholders, analyze ways of controlling substances on a case by base basis, reviewing the health and environmental risks they pose, the availability of substitutes, technological, socioeconomic and other considerations. Controls may improve the safety requirements for the use of a substance, limit its use or the quantities that may be discharged into the environment, or ban the substance.
Controls are never automatic, however.
In the case of substances deemed carcinogenic, the need for further risk reduction measures should be reviewed on an ongoing basis, as new technologies become available and socioeconomic factors change.