Minimal Risk Level (MRL) 1 : An estimate of daily human exposure to a hazardous substance that is likely to be without an appreciable risk of adverse noncancer health effects over a specified route and duration of exposure
Department of Health and Human Services (US federal public health agency), The Agency for Toxic Substances and Disease Registry (ATSDR), Glossary (Total Petroleum Hydrocarons), GA, USA 1999. http://www.atsdr.cdc.gov/toxprofiles/tp123-c9.pdf, (Globally Harmonized Sys of Class and Labl of Chem - Brit) {635}