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: 2094593–2097516

2                   Beryllium

2.1              General
Several comprehensive reviews of beryllium in the environment and its toxicity to humans are available and should be consulted for more detailed information (ATSDR 2002; WHO 1993; WHO 2001). The following provides a summary of the key aspects of beryllium that are relevant to the derivation of a soil HIL.

Beryllium is a steel grey, brittle metal that is not found as the free metal in nature. There are approximately 45 mineralised forms of beryllium. The most important beryllium minerals in the world are beryl (3BeOAl2O36SiO2) and bertrandite (Be4Si2O7(OH)2) (ATSDR 2002). Beryllium is the lightest of all solids and chemically stable substances, with an unusually high melting point, specific heat, heat of fusion, and strength-to-weight ratio. Due to its high affinity for oxygen, a very stable surface film of beryllium oxide (BeO) is formed on the surface of metallic beryllium and beryllium alloys, providing high resistance to corrosion, water and cold oxidising acids (WHO 1993).

Occupational exposure to beryllium has been associated with acute and chronic lung diseases. The acute disease is normally associated with inhalation exposures to high levels of soluble beryllium salts (e.g. sulphate, chloride) and BeO, and may lead to chronic disease. The chronic disease is associated with long-term inhalation exposures to dust particles containing beryllium, has an immunological component and a latent period, which varies depending on the beryllium species. Dermatological effects may also occur on skin contact (Di Marco & Buckett 1996).

2.2              Previous HIL
The derivation of the previous HIL (HIL A = 20 mg/kg) for beryllium is presented by Di Marco & Buckett (1996). In summary, the HIL was derived on the basis of the following:
    * Intakes of beryllium from other sources were estimated with dietary intakes considered most significant for the general population. Based on the information available from Canada (considered more relevant than US data), background intakes of beryllium were assumed to be 0.65 µg/kg/day for preschoolers and 0.17 µg/kg/day for adults.
    * A provisional tolerable daily intake (PTDI) of 1 µg/kg/week based on the US EPA RfD of 5 µg/kg/day (derived from a NOEL of 0.54 mg/kg/day and an uncertainty factor of 100), however an additional uncertainty factor of 5 was considered more appropriate to address limitations with the critical study used (no other studies were available)
    * Ingestion of both soil and dust by an infant (2.5 years) has been considered assuming 1% is bioavailable.
    * Dermal absorption has been considered to be low with a conservative assumption of 0.1% considered.
    * Inhalation of beryllium in dust has been considered outdoors and indoors, assuming a dust concentration of 100 µg/m3 and outdoor dust contributes 75% to indoor dust.
    * Soil criteria derived on the