Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:7:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 7 (pt 2/4)
Character Range: 2669561–2672489

significance than ingestion of soil. While likely to be negligible, potential inhalation exposures associated with dust have been considered in the HIL derived.

7.3.4         Plant Uptake
Limited information is available on the potential for plant uptake of bifenthrin. ATSDR (2003) notes that in soils, pyrethrins adsorb strongly and do not leach appreciably into groundwater. These compounds are not considerably taken up by the roots of vascular plants; however, they are deposited upon the leafy region of vegetation following spraying.

Where the application of the product is not of concern, there is limited potential for bifenthrin to be present in soil solution, and available for plant uptake, due to its strong adsorption to soil and its limited solubility.

On this basis, the potential for plant uptake into home-grown fruit and vegetable crops is not considered to be significant and has not been considered in the derivation of a soil HIL.

7.3.5         Intakes from Other Sources – Background
Background intakes were evaluated by Taylor & Di Marco (2003). No Australian data was identified and intakes from water, food, air, consumer products and soil were assumed to comprise 20% of the adopted ADI, resulting in background intakes from sources other than soil as 80%.

Synthetic pyrethroid pesticides were included in The 23rd Australian Total Diet Survey (FSANZ 2011). Intake associated with the detected residues of bifenthrin for children aged 25 years was 0.072 µg/kg/day, and  for children aged 612 years was 0.085 µg/kg/day, similar to the intake estimated for adults.

Limited other data is available in Australia, where a study on bifenthrin in air within a home after termite treatment did not detect bifenthrin concentrations (Richards 2003). Pyrethrins and pyrethroids are used in both indoor and outdoor settings to control insects; therefore, these compounds are frequently detected in the air of homes and buildings after their use. Data from the USA (ATSDR 2003) reported concentrations of pyrethrins in the order of 0.10.3 µg/m3 sometime after application (up to 84 days after application). Intakes by toddlers associated with these concentrations are in the range of 0.06–0.2 µg/kg/day, significantly higher than estimated from dietary intakes. It is noted that if these insecticide sprays are regularly used, indoor air concentrations may be higher.

On the basis of the above, intakes associated with bifenthrin (assuming it comprises 100% of the pyrethrins reported in indoor air in the US) may comprise up to 0.28 µg/kg/day for toddlers, approximately 3% of the recommended oral TRV. For the purpose of establishing an HIL, intakes from other sources has been taken to be 10% of the adopted TRV.

7.4              Identification of Toxicity Reference Values

7.4.1         Classification
The International Agency for Research on Cancer (IARC) and US EPA have not classified bifenthrin