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Toxic 100 Water Polluters Technical Notes (2018 Report based on 2015 data)

TRI and RSEI Data

The Toxics Release Inventory (TRI), compiled by the U.S. Environmental Protection Agency (EPA) in accordance with the Emergency Planning and Community Right-to-Know Act of 1986, annually reports the weight (in pounds) of each of approximately 600 toxic chemicals released into the environment by major industrial facilities in the United States. Our analysis uses year 2015 releases of toxic chemicals into surface water nationwide. We combine direct surface-water and post-sewage-treatment releases.

The EPA has developed a method called Risk Screening Environmental Indicators (RSEI) to make the TRI reports more useful to the public. The EPA provides additional information to assess the potential chronic human health hazard posed by toxic releases:

  • toxicity, or how dangerous the chemical is on a per-pound basis; and
  • removal efficiency, or how much of the chemical is prevented from entering surface water following transfers for sewage treatment at Publicly Owned Treatment Works (POTWs).

EPA matches each chemical to a toxicity weight that expresses the relative toxicity of the chemical per pound or per unit of concentration. Although all TRI chemicals are hazardous, their toxicities vary greatly.  For example, the toxicity weight for ingesting the chemical zinc is about 3 while the toxicity weight for ingesting mercury is 10,000. It is roughly than 3,000 times more potentially harmful to ingest mercury as it is to ingest an equal quantity of zinc. The chemicals reported in the Toxics Release Inventory vary by ten orders of magnitude in their oral toxicity weights (from 0.02 for sulfuric acid to 1,400,000,000 for dioxin).  The enormous variation in toxicity limits the usefulness of comparisons on the basis of the simple mass (pounds) of chemicals released. By multiplying the mass of each toxic release by its toxicity weight, EPA can compare the toxic significance of releases of different chemicals.

The EPA's toxicity-weighting system is based on peer-reviewed toxicity databases including those of the EPA's Integrated Risk Information System (IRIS), the EPA's Office of Pesticide Programs (OPP) Reference Dose Tracking Reports, the U.S. Department of Health and Human Services Agency for Toxic Substances and Disease Registry (ATSDR), the California Environmental Protection Agency (CalEPA) Office of Environmental Health Hazard and Assessment (OEHHA), and the EPA's Health Effects Assessment Tables (HEAST). For some of the chemicals listed in the TRI, no consensus has been reached regarding the appropriate toxicity weight, and these chemicals are excluded from the analysis. In the TRI data for the year 2015, chemicals with toxicity weights account for more than 97% of the reported pounds for all water releases. Further details on the toxicity weights are available from the EPA at https://www.epa.gov/rsei/rsei-toxicity-data-and-calculations.

For many chemicals in the TRI, the US EPA Risk Reduction Engineering Laboratory estimates the removal efficiency, or how successfully sewage treatment removes toxic chemicals from wastes that are transferred for treatment based on the technology used and the type of influent.  Toxic chemicals that are not removed are released into surface water with other effluents post-treatment: details are at https://www.epa.gov/sites/production/files/2015-12/documents/technical_appendix_b-pchem_v2.3.4.pdf

The product of the toxicity weight and the quantity released, including both direct and estimated post-treatment releases, is called the RSEI Hazard and represents potential human chronic-health hazard from water releases of the toxic chemicals.  The extent of population risk also depends on other determinants of exposure, including dilution and sedimentation in waterways, fish consumption from and recreation in contaminated waters, the location of drinking-water intakes, and the effectiveness of drinking-water treatment in achieving safe levels for regulated contaminants, and the number of persons affected.

The data cover toxic releases from point-source industrial facilities reporting to TRI.  Agricultural pollution, boating and shipping, runoff from streets and roads, and other important sources of water pollution are not included in the analysis. The data are additionally limited to TRI listed toxic chemicals.

The Corporate Toxics Information Project (CTIP) of the Political Economy Research Institute (PERI) at UMass Amherst adjusts the TRI data so that they represent the most current available about the reporting year, in case companies revise earlier TRI reporting.  In the case of downward revisions of pounds released,  RSEI Hazards are adjusted based on the linear relation between pounds released and that release's RSEI Hazard. Upward revisions or new reports are noted but do not engender adjustments of the RSEI Hazard.

Parent Company Matching

Using information on company ownership of facilities from the TRI reports, company websites, the CrocTail database of SEC filings, and news reports, we matched each facility to its parent company. Each facility was assigned either one or two parents as follows: 

  • If more than 50% of a facility was controlled by a single parent, that parent was assumed to have final control over the facility's operations, and was assigned full responsibility for the facility's pollution.
  • If two companies each controlled 50% of a facility (i.e. it was a 50/50 joint venture), then its pollution was divided between the two companies.
  • If a single company controlled 50% of a facility and no other single entity controlled the other 50%, that company was considered to be the parent of the facility.
  • If no parent controlled 50% of a facility, the facility was considered to be its own parent.

In some cases we updated parent companies according to mergers, acquisitions, and corporate name changes that took place through late 2017, under the principle that when one company acquires another, it takes responsibility for that company's past pollution. We also combined some U.S. subsidiaries of common foreign companies together.

We then aggregated the RSEI hazard for water releases of toxics by the facilities owned by each parent company, and ranked companies on this basis. Facilities that were owned 50%/50% by two companies had half of their hazard assigned to each parent.  

The Toxic 100 Water application also shows data from individual facilities owned by each parent company and from chemicals at each.  For each parent company, the percentage of the company’s total score that is from a single facility is displayed in the Toxic 100 Water list if that percentage is over 70%.  This helps to identify companies whose overall chronic human health air risk is dominated by a single source.

Large Company lists

The Toxic 100 Water Polluters list reports the top polluters among the companies that appeared on any of the following lists of large US and foreign-owned corporations:

  • Forbes Global 2000, 2017 ranking (only first 500 companies)
  • Forbes America's Largest Private Companies, 2017 version
  • Fortune 500, version as of end of fiscal year 2017
  • Fortune Global 500, 2017 version
  • S&P 500 as of July 26, 2017

Pollution data for the entire universe of companies that report toxic water emissions to EPA can be accessed via the searchable database that accompanies the Toxic 100 list.

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