Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:2:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 2 (pt 1/6)
Character Range: 2472437–2475483

2                   Aldrin + Dieldrin

2.1              General
Several comprehensive reviews of aldrin and dieldrin in the environment and their toxicity to humans are available and should be consulted for more detailed information (ATSDR 2002; WHO 1989). The following provides a summary of the key aspects of these compounds that are relevant to the derivation of a soil HIL.

Aldrin and dieldrin are the common names of two structurally similar compounds that were historically used as insecticides. These two chemicals are discussed together because aldrin is readily converted to dieldrin once it enters either the environment or the body, and both compounds reportedly have similar health effects. Aldrin predominantly contained the compound hexachlorohexahydrodimethanonaphthalene (HHDN) and was also produced under the following trade names; Aldrec, Aldrex, Drinox, Octalene, Seedrin, and Compound 118 (ATSDR 2002). Technical-grade aldrin contained not less than 85% aldrin with common impurities including isodrin, hexachlorobutadiene, chlordane, octachlorocyclopentene and toluene (ATSDR 2002).

Dieldrin was manufactured by the epoxidation of aldrin. Technical grade dieldrin, which was also produced under the trade names Alvit, Dieldrix, Octalox and Red Shields, contained no less that 85% by weight hexachloroepoxyoctahydrodimethanonaphthalene (HEOD). Pure HHDN and HEOD are structurally similar, stable white powders or crystals with a mild chemical odour. Commercial grade aldrin and dieldrin are tan coloured powders. Aldrin and dieldrin have low vapour pressure and are relatively insoluble in water (ATSDR 2002).

Aldrin and dieldrin, which do not occur naturally in the environment, were synthesised for commercial use as contact insecticides. Both chemicals were widely used against soil-dwelling pests in agriculture, particularly in the corn and citrus industries (ATSDR 2002). They were also used for the protection of wood structures or electrical and telecommunication cables against termites and woodborers.

They were used in Australia and across the world from the 1950s until their commercial distribution was restricted in the 1970s. By the end of 1980, there was a significant reduction on the number of aldrin and dieldrin products formally approved. All uses of these products were deregistered by 1985.

2.2              Previous HIL
The derivation of the previous HIL (HIL A = 10 mg/kg) for aldrin and dieldrin is presented by Di Marco (1993) and NEPC (1999). In summary, the HIL was derived on the basis of the following:
    * Background intakes were considered in the derivation of the current HIL with the intakes from food, water and ambient air considered to comprise 40% of the adopted ADI.
    * An ADI of 0.0001 mg/kg/day referenced from the JMPR (1985) was considered. An additional factor of 3 was used because of the uncertainties associated with the bioavailability estimates adopted and exposure levels in the future.
    * Dermal absorption of aldrin and dieldrin was considered to be 5%.
    *