Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:6:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 6 (pt 3/6)
Character Range: 2655301–2658195

the bulk dissipating through volatilisation. Absorption by roots from the soil is also poor. This is further supported by studies presented by JMPR (1972) that show that the uptake of chlorpyrifos or its degradation products is insignificant through the foliage or roots. Only through the use of specialised techniques has plant uptake of chlorpyrifos been significant.

Chlorpyrifos has the potential to strongly adsorb to soil and sediments (based on log Koc of 3.73 from ATSDR (1997)) and has low water solubility. Hence the potential for chlorpyrifos to be present in soil solution, and subsequent uptake by plants, is considered to be low.

On the basis of the available information, plant uptake into edible fruit and vegetable crops is considered low and has not been considered in the derivation of soil HILs.

6.3.5         Intakes from Other Sources – Background
Background intakes were evaluated in more detail by Taylor & Di Marco (2003), where data (from Australia where relevant) for food, water and air were considered. Background intakes were estimated to range from 0.81 µg/kg/day for adults and infants to 1 µg/kg/day for toddlers. Dietary intakes of 0.63 µg/kg/day for toddlers (based on older surveys) were higher than currently reported. Current data on intakes from food and air (most significant pathways considered) include:
    * Intakes of chlorpyrifos based on The Australian Total Diet Survey (FSANZ 2011) were 0.23 µg/kg/day for children aged 25 years (most significant). While it is accepted that there are limitations in the data provided in these studies, the data is consistent with information from studies conducted in the US (ATSDR 1997) and have been considered indicative of potential intakes from food.
    * A range of air concentrations have been reported for chlorpyrifos, during or immediately after application, some period after application, and ambient concentrations. Mean concentrations of chlorpyrifos in homes treated with termiticide several years previously were 2.23 µg/m3 (EA 2001). Intakes derived from these concentrations are estimated to be 1.4 µg/kg/day, significantly more than intakes derived from dietary sources.
Other sources of exposure may be associated with house dust, though as there is limited data available to quantify exposures related to the presence of chlorpyrifos in house dust, it has not been included in this evaluation. It is noted that the derivation of the soil HIL considers ingestion of both soil and dust.

Consideration of intakes derived from food and air suggests background intakes may be approximately 1.6 µg/kg/day, which comprise approximately 50% of the recommended TRV. Review of dietary intakes by APVMA (2009), based on a conservative estimate of chemical residues in food, indicated that intakes may comprise up to 55% of the TRV, similar to the estimate presented on the basis of the above.

As