8REGULATIONS, ADVISORIES, AND GUIDELINES

MRLs are substance-specific estimates, which are intended to serve as screening levels, are used by ATSDR health assessors and other responders to identify contaminants and potential health effects that may be of concern at hazardous waste sites.

ATSDR has derived an acute-duration inhalation MRL of 0.03 µg Cd/m3 for cadmium. This MRL is based on a LOAEL of 0.088 mg Cd/m3 (LOAELHEC of 0.01 mg Cd/m3) for respiratory effects in rats exposed to cadmium oxide 6.2 hours/day, 5 days/week for 2 weeks (NTP 1995) and an uncertainty factor of 300 (10 for the use of a LOAEL, 3 for extrapolation from animals to humans with dosimetric adjustments, and 10 for human variability).

ATSDR has derived a chronic-duration inhalation MRL of 0.01 µg Cd/m3 for cadmium. This MRL is based on the 95% lower confidence limit of the urinary cadmium level associated with a 10% extra risk of low molecular weight proteinuria (UCDL10) estimated from a meta-analysis of environmental exposure data. An air concentration that would result in this urinary cadmium level (0.5 µg/g creatinine), assuming a dietary cadmium intake of 0.3 µg/kg/day, was estimated using biokinetic models. The estimated air concentration of 0.1 µg Cd/m3 was divided by an uncertainty factor of 3 for human variability and a modifying factor of 3.

The EPA has not established a reference concentration (RfC) for cadmium.

ATSDR has derived an intermediate-duration oral MRL of 0.5 µg Cd/kg/day for cadmium. This MRL is based on a BMDLstd1 of 0.05 mg Cd/kg/day for skeletal effects in young female rats exposed to cadmium chloride in drinking water for 6, 9, or 12 months (Brzóska and Moniuszko-Jakoniuk 2005d) and an uncertainty factor of 100 (10 for extrapolation from animals to humans and 10 for human variability).

ATSDR has derived a chronic-duration oral MRL of 0.1 µg Cd/kg/day for cadmium. This MRL is based on the UCDL10 for low molecular weight proteinuria estimated from a meta-analysis of environmental exposure data. A cadmium intake that would result in the UCDL10 (0.5 µg/g creatinine) at age 55 was estimated using pharmacokinetic models. The cadmium intake of 0.33 µg/kg/day was divided by an uncertainty factor of 3 for human variability.

The EPA has established a reference dose (RfD) of 5×10−4 mg/kg/day in water and 1×10−3 mg/kg/day in food (IRIS 2012). The RfD is based on a chronic intake that would result in a kidney concentration of 200 µg/g ww.

The international and national regulations, advisories, and guidelines regarding cadmium in air, water, and other media are summarized in Table 8-1.

Table 8-1. Regulations, Advisories, and Guidelines Applicable to Cadmium.

Table 8-1

Regulations, Advisories, and Guidelines Applicable to Cadmium.

Cadmium compounds are included on the list of 189 chemicals listed as hazardous air pollutants under Section 112 of the Clean Air Act as amended (EPA 2007). Cadmium also is on the list of chemicals appearing in the Emergency Planning and Community Right-To-Know Act of 1986 (EPA 2008g). Under Title III of this statute, owners and operators of facilities that manufacture, import, process, or otherwise use the chemicals on this list of report annually their release of those chemicals to any environmental media.

Cadmium and cadmium chloride are designed as hazardous substances under Section 311 of the Clean Water Act; any discharge of these chemicals over a specified threshold level into navigable waters is subject to reporting requirements (EPA 2008c).

Cadmium is a hazardous waste under the Resource Conservation and Recovery Act (RCRA) under several circumstances. Groundwater monitoring is required at municipal solid waste landfills (EPA 2008d) and cadmium is considered a priority persistent, bioaccumulative, and toxic (PBT) chemical under RCRA waste minimization chemical listing (EPA 1998).