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Methodology

January 13, 2006

Stolen Inventory (National): Methodology

Study objective

The objective of the analyses that underly this study was to identify industrial chemicals that meet the Environmental Protection Agency's (EPA's) criteria for classification as persistent bioaccumulative toxic (PBT) chemicals, a category reserved for compounds that present the greatest threats to human health and the environment. Specifically, we sought to identify chemicals that meet the Agency's PBT criteria established for stringent pollution reporting under the Toxics Release Inventory (TRI) program. We focused on chemicals meeting PBT criteria that are not among the 20 PBT chemicals currently recognized in the program. In our assessment we considered all chemicals with available PBT data, including those currently subject to standard (non-PBT) TRI reporting, as well as those not subject to any reporting at all under TRI.

We focused our work on identifying PBT chemicals not yet recognized as such by EPA because of the particular risks these chemicals pose to human health and the environment, and because according to EPA such chemicals merit stronger pollution reporting requirements:

Toxic chemicals that persist and bioaccumulate are of particular concern because they remain in the environment for significant periods of time and concentrate in the organisms exposed to them. EPA believes that the public understands that these PBT chemicals have the potential to cause serious human health and environmental effects resulting from low levels of release and exposure. Lowering the reporting thresholds for PBT chemicals will ensure that the public has important information on the quantities of these chemicals released or otherwise managed as waste, that would not be reported under the 10,000 and 25,000 pound/year thresholds that apply to other toxic chemicals.


Criteria for classification of a chemical as persistent, bioaccumulative, and toxic

The Emergency Planning and Community Right to Know Act (EPCRA) of 1986 mandated a program known as the Toxics Release Inventory (TRI) under which U.S. facilities in a wide range of industries report annually their disposal and emissions of 650 industrial chemicals. Facilities must submit TRI reports detailing waste disposal and emissions if they handle at least 10,000 pounds a year, manufacture 25,000 pounds per year, or discharge or dispose of at least 500 pounds per year, for any chemical covered by the TRI.

Congress gave EPA the authority to set alternate reporting thresholds for chemicals so long as the resulting data continued to capture the substantial majority of releases at facilities. The Agency determined that alternate (lower) reporting thresholds were warranted for persistent bioaccumulative toxic (PBT) chemicals because of the unique ability of these chemicals to cause long-lasting harm to wildlife, ecosystems, and in many cases, humans at low levels of exposure:

Current reporting thresholds (10,000 and 25,000 pounds) "are inadequate to ensure that the public has access to important information about the quantities of these PBT chemicals which enter their communities from local industrial facilities. By lowering the existing thresholds to 10 and 100 pounds, EPA believes the public will have access to necessary basic environmental data about these chemicals" [EPA 1999a].

On October 29, 1999, EPA published a final rule which strengthened reporting requirements under the TRI program for 18 persistent, bioaccumulative, and toxic (PBT) chemicals and chemical categories under the Toxics Release Inventory Program [EPA 1999b]. On January 17, 2001 the Agency published a rule mandating the same requirements for two additional PBT compounds [EPA 2001a] bringing the total number of PBTs with expanded reporting requirements up to 20. For 15 of these PBT chemicals, EPA lowered reporting thresholds from 10,000 or 25,000 pounds to between 10 and 100 pounds. For five PBT chemicals EPA added first-ever reporting requirements under the TRI, with each chemical assigned strict reporting limits ranging from between 0.1 grams and 100 pounds. EPA assigned a reporting threshold of 0.1 grams for dioxin and dioxin-like compounds, which are considered very highly persistent and bioaccumulative; 10 pounds for 11 of the 18, each of which the Agency considered to be highly persistent and bioaccumultive; and 100 pounds for the remaining six PBT chemicals [EPA 1999a].

In their rulemaking, EPA developed criteria by which chemicals would be classified, for the purposes of TRI reporting, as persistent, bioaccumulative, and toxic. These are the criteria we have used to identify PBTs for the purposes of our study [EPA 1999a]:

  • Persistence: A chemical is considered persistent (resistant to breakdown and long-lived in the environment) if it is characterized by a degradation half-life, the time required for 50 percent of a chemical to break down, of two months or greater in water, soil, or river and stream sediments. Chemicals that meet this criteria are expected to persist in the environment for a least a year after release. For instance, a chemical with a two-month (60 day) degradation half life remains in the environment at just over one percent of its original amount one year after its release. Persistence is also indicated by a degradation half-life in the air of two days or greater, a lower half-life threshold than that for water, air, and sediment that is dictated by the much faster chemical transport times typical for air relative to other environmental media.

  • Bioaccumulation: EPA defines bioaccumulation as "the net accumulation of a substance by an organism as a result of uptake from all environmental sources," and the related property of bioconcentration as "the nondietary accumulation of chemicals in aquatic organisms" [EPA 1999a]. These properties are represented by parameters known as the Bioaccumulation Factor (BAF) or Bioconcentration Factor (BCF), each of which is calculated as the ratio of a substance's concentration in the tissue of a plant or animal to its concentration in relevant exposure media (water in the case of BCF, and food and other environmental exposure sources in the case of BAF). For the purposes of PBT reporting under the TRI, EPA considers a chemical bioaccumulative if either its BCF or BAF exceeds 1000.

  • Toxicity: EPA's criteria for considering a chemical toxic for the purposes of establishing the chemical as PBT (and requiring more comprehensive TRI reporting) are laid out in the Agency's final rule published in October 1999 mandating expanded TRI reporting for 18 PBTs. In this rule EPA states that the selected PBT chemicals are "reasonably anticipated to cause serious or irreversible chronic human health effects at relatively low doses or ecotoxicity at relatively low concentrations" [EPA 1999a]. This is the criteria used in EWG's assessment.

Data sources

To assess the persistence, bioaccumulation, and toxicity of HPV chemicals, Environmental Working Group analyzed five government and industry data resources containing a total of 1.5 million test results altogether:

  • IUCLID (International Uniform Chemical Information Database) [IUCLID 2004a]: This database currently contains records submitted by the international chemical industry on over 2600 international high production volume chemicals. IUCLID was designed to meet the requirements for storing and exchanging information on OECD HPV Chemicals Program, the US-EPA HPV Chemical Challenge Program, the EU Existing Chemicals Program and the EU Biocides Program. It contains records on basic chemical properties (e.g. melting points), persistence (e.g. biodegradation, field monitoring), bioaccumulation factors, ecotoxicity (e.g. fish tests), human toxicity (e.g. developmental toxicity, carcinogenic potential, et cetera to assess the danger to humans), and risk assessments.
  • EPA High Production Volume Chemical Challenge Program [EPA 2006a]: Data maintained by EPA in hundreds of individual PDF-formatted, industry-submitted data summary files, this compilation of SIDS data currently covers nearly 400 chemicals and chemical families that are produced in or imported into the U.S. in quantities of at least one million pounds per year. These data submissions are the result of companies' voluntary participation in EPA's High Production Volume Chemical Challenge Program, and contain information on basic chemical properties (e.g. melting point), persistence (e.g. biodegradation, field monitoring), bioaccumulation factors, ecotoxicity (e.g. fish tests), human toxicity (e.g. developmental toxicity, carcinogenic potential, et cetera to assess the danger to humans), and risk assessments. EPA continues to accept data submissions under this program, and the Agency may eventually transform data contained in these documents into an electronic database detailing the testing results. Although we could not systematically use this data resource in systematic evaluations of persistence, bioaccumulation, and toxicity, we did use the submissions to verify chemicals determined to be PBTs through other data sources.
  • ECOTOX [EPA 2004a]: Contains over one million records on bioaccumulation and ecological toxicological test results and endpoints covering 8,500 different chemicals broken down in 50 parameters measuring 170 different effects on organisms. This database represents a compilation of various sources of data developed by a wide range of government, industry, and academic institutions, integrated into a single interface by Department of Defense and EPA, with the EPA currently maintaining the database.
  • Environmental Fate Database (EFDB) [SRC 2004]: Contains over 30,000 records in 29 different categories of persistence test results and endpoints (e.g. biodegradation, Henry's Law constant) covering nearly 2,000 chemicals. Developed by the Syracuse Research Corporation (SRC) under the auspices of the EPA. Obtained directly from SRC.
  • Registry of Toxic Effects of Chemical Substances (RTECS) [RTECS 2005a]: Human and animal toxicological information (e.g. developmental toxicity, carcinogenic potential, et cetera to assess the danger to humans) with citations on over 160,000 chemical substances from more than 2,500 sources. Originally compiled by NIOSH and now maintained by Elsevier MDL, Inc. EWG obtained the database from the Canadian Centre for Occupational Health and Safety.