Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:6:p5
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 6 (pt 5/12)
Character Range: 1062714–1065584

abbreviated as 1x10-6 or 10-6) was considered an insignificant risk and used as a maximum value for defining permissible environmental concentrations.

The US EPA has set a lifetime cancer risk goal of 1 in 1,000,000 for the regulation of individual genotoxic chemicals. However, in determining an acceptable cancer risk, EPA determined a safe emissions level, and then added a margin of safety in view of uncertainties in scientific knowledge. The US EPA adopted a general policy that a lifetime cancer risk of 1 in 10,000 for the most exposed person may constitute acceptable risk and that a margin of safety should be added to reduce the risk for the greatest possible number of persons to an individual lifetime risk no higher than 1 in 1,000,000 (NRC 1994).

The adoption of 1 in 1,000,000 as a criterion for assessing excess lifetime cancer risk was originally specified by the US Food and Drug Administration (FDA) in the 1970s to identify food additives that did not require further assessment. The criterion was an arbitrary decision and was not based on any scientific rationale. The criterion was also subsequently adopted by other US and international agencies without any rigorous debate (Kelly 1991).

The World Health Organization (WHO) has recognised that the setting of environmental standards for air and water contaminants is the responsibility of national agencies. WHO generally provides guideline values for genotoxic carcinogens corresponding to lifetime risks of 1 in 10,000, 1 in 100,000 and 1 in 1,000,000 from which national agencies can select a value to be used in their guidelines  (WHO 2000).  By basing its guideline values on risks between 1 in 10,000 and 1 in 1,000,000, WHO is implying that it considers that acceptable risk lies somewhere in the range 1 in 10,000 and 1 in 1,000,000. WHO also recognises that the acceptability of risk depends on scientific data, social, economic and political factors, and the perceived benefits arising from circumstances that might be associated with exposure to the carcinogen e.g. the health benefits of disinfecting drinking water, are greater than the risks that might be posed by potentially carcinogenic disinfection by-products.

In Australia there is no universally accepted criterion for acceptable excess lifetime cancer risk. Lower incremental lifetime cancer risk values (1x10-6) are commonly adopted in guidance that addresses population-wide exposures, such as the Australian Drinking Water Guidelines (NHMRC 2011), which has adopted a lifetime risk level of 1 in 1,000,000 for genotoxic carcinogens.

NSW EPA considers an excess lifetime cancer risk of less than 1 in 1,000,000 as acceptable and cancer risks greater than 1 in 10,000 as unacceptable (NSW DEC 2005). In between these two limits, proponents should demonstrate best practice for development applications to be approved.