Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:8:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 8 (pt 1/4)
Character Range: 2548924–2551960

8                   Methoxychlor

8.1              General
Several comprehensive reviews of methoxychlor in the environment and its toxicity to humans are available and should be consulted for more detailed information (ATSDR 2002; ATSDR 2009; JMPR 1977; OEHHA 1999). The following provides a summary of the key aspects of methoxychlor that are relevant to the derivation of a soil HIL.

Methoxychlor does not occur naturally in the environment. Pure methoxychlor is a pale yellow powder that has a slightly fruity or musty odour. It does not readily evaporate or dissolve in water (ATSDR 2002).

Methoxychlor is a manufactured chemical used for controlling insects. The chemical is effective against flies, mosquitoes and cockroaches and is used on agricultural crops and livestock, in animal feed barns and in grain storage bins. Some pesticide products that contain methoxychlor are used for controlling insects in gardens or on household pets (ATSDR 2002).

It is noted that the only methoxychlor product registration in Australian was cancelled in mid-1987 (information available from APVMA).

8.2              Previous HIL
No previous HIL is available for methoxychlor (NEPC 1999).

8.3              Significance of Exposure Pathways

8.3.1         Oral Bioavailability
Insufficient data is available to adequately define the bioavailability of methoxychlor hence 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.

8.3.2         Dermal absorption
Insufficient data is available on the dermal absorption of methoxychlor from soil. Hence the default value of 0.1 (10%) suggested by US EPA (1995) for pesticides has been adopted in the derivation of HILs.

8.3.3         Inhalation of Dust
Methoxychlor is 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.

8.3.4         Plant Uptake
There is no information regarding the plant uptake of methoxychlor following its application as a pesticide (ATSDR 2002). Methoxychlor has a high Koc value (log Koc = 4.9) and low solubility in water (ATSDR 2002), suggesting that the compound is largely bound to soil particulates and is immobile in soil. For plant uptake to be significant, the chemicals must be able to partition to soil water. With respect to methoxychlor bound to the soil, the potential for partitioning to soil water is considered to be low and hence plant uptake is considered to be negligible.

8.3.5         Intakes from Other Sources – Background
No data is available regarding background concentrations of methoxychlor in Australia. The 23rd Australian Total Diet Study (FSANZ 2011) did not detect methoxychlor in any products sampled and tested. US