Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 1/4)
Character Range: 2433515–2436610

4                   Total Cresols

4.1              General
Several comprehensive reviews of cresols in the environment and their toxicity to humans are available and should be consulted for more detailed information not presented in this summary (ATSDR 2008; WHO 1995). The following provides a summary of the key aspects of cresols that are relevant to the derivation of a soil HIL.

Cresols are a group of isomers comprising a single benzene ring, a hydroxyl group and a methyl group (C7H8O). There are three structural isomers, including m-cresol (2-methylphenol), p-cresol (3-methylphenol), and o-cresol (4-methylphenol). These isomers may occur separately or as a mixture (ATSDR 2008). In their pure form, cresols are colourless solids, while mixtures are more commonly liquids. Cresols are semi-volatile compounds with moderate solubility in water and a medicinal-type odour (ATSDR 2008). The abundance of p-cresols in the environment is significantly greater than that of the alternative isomers, as is the abundance of o-cresol relative to that of m-cresols. However, there is a greater amount of information and studies surrounding the health effects associated with m- and o-cresols. It should be noted that the behaviour of all three isomers in the environment is considered to be similar.

Cresols are both a naturally occurring and manufactured group of chemicals that may be used as solvents, disinfectants, deodorisers, wood preservatives and to make other chemicals (ATSDR 2008). O-cresol is used in the manufacture of several dye intermediates (ATSDR 2008). P-cresol is predominantly used in the manufacture of anti-oxidants, synthetic food flavours and fragrances, and m-cresol is used in the synthesis of many herbicides and insecticides (ATSDR 2008). Cresols occur in various plant oils including peppermint, sandalwood, jasmine, Easter lily, ylang ylang, eucalyptus and camphor.

4.2              Previous HIL
No previous HIL is available for cresols (NEPC 1999).

4.3              Significance of Exposure Pathways

    4.3.1         Oral Bioavailability
Insufficient data is available to adequately define the bioavailability of cresols in the range of contaminated sites that may need to be considered in Australia. On this basis, a default approach of assuming 100% oral bioavailability has been adopted in the derivation of an HIL. It is noted that a site-specific assessment of bioavailability can be undertaken where required.

    4.3.2         Dermal absorption
Insufficient data is available on the dermal absorption of cresols from soil. Hence the default values of 0.1 (10%) suggested by US EPA (2004) for semi-volatiles has been adopted in the derivation of HILs.

    4.3.3         Inhalation of Dust
Cresols are not considered sufficiently volatile to be of significance and inhalation exposures associated with particulates outdoors and indoors are expected to be of less significance than ingestion of soil. While likely to be negligible, potential inhalation exposures associated with dust have been considered in the HIL derived.

    4.3.4         Plant