Indicator Reference Sheet - March 6, 2022

Toxic Substances and Waste

U.S. Environmental Protection Agency

Indicator Names

•	Toxic Release Inventory Sites, Count in Watershed (WS)

•	Toxic Release and Exposure Potential in Watershed (WS)

Indicator Description
Background

The US Environmental Protection Agency (EPA) maintains
the Toxics Release Inventory (TRI) to track the
management of certain toxic substances that may pose a
significant threat to human health and the environment.1
Facilities that report to TRI are typically larger and involved
in manufacturing, metal mining, power generation,
chemical manufacturing, and waste treatment.1

To help users explore data on releases of toxic substances
from industrial and federal facilities, EPA developed the
Risk-Screening Environmental Indicators (RSEI) model using
TRI information.2 For each facility in the TRI, the RSEI
model calculates scores that reflect the potential for toxic
substance release and human exposure from the
magnitude of toxic releases in air emissions and
wastewater discharge, the size of potentially exposed
populations, and the estimated chemical dose at points of
human exposure.2

What the Indicators Measure

These indicators measure the following characteristics of a
HUC12 subwatershed:*

•	Toxic Release Inventory Sites, Count in Watershed
(WS) -the number of TRI sites in the HUC12.

•	Toxic Release and Exposure Potential in Watershed
(WS) -the sum of RSEI scores reported between 2015
and 2019 for TRI facilities in the HUC12 (Figure 1).
Higher values correspond to greater potential for toxic
substance release and exposure relative to other
HUC12s.

Relevance to Water Quality Restoration and Protection
TRI facilities are regulated to reduce risk of toxic exposure,
and their presence alone does not mean hazardous
substances are harming a population or the environment.3
However, allowable discharges of toxic substances may be
permitted, and accidental toxic releases can occur. Living
near TRI and other hazardous waste facilities has been
associated with human health effects, such as increased
cancer rates, asthma hospitalizations, and stroke
mortality.4

Minorities, low-income populations, and other over-
burdened communities may face a higher risk for toxic

Indicator Category | Stressor
Subcategory j Hazardous Waste & Wastewater
Available in RPS Tool files for all lower 48 states

Sum of RSEI Scores for TRI Facilities

>8 Million

Figure 1. Map of Toxic Release and Exposure Potential in
Watershed for HUC12s across the contiguous US.

substance exposure compared to other groups. For
instance, a study of the distribution of TRI facilities in
Charleston, South Carolina, found that TRI facilities tend to
be concentrated in areas with higher poverty,
unemployment, and non-white populations and lower
education levels.5 A national study of toxic substance
accidents found that surrounding communities tended to
have a high proportion of African-American populations.6
Such inequities in toxic exposure may contribute to
disparities in the health of disadvantaged communities.7,8

These indicators can be used to the evaluate the relative
potential for exposure to toxic substances and waste
within a group of HUC12s. They can be used with
additional indicators of pollutant exposure and
demographics (income, race, education, etc.) to identify
HUC12s with populations that may face a greater pollution
burden and associated health impacts. Such HUC12s may
be considered priorities for follow-up restoration or
protection efforts

Processing Method

TRI site counts for HUC12s were derived from information
in the EPA Facility Registry Service (FRS). The FRS is EPA's
centralized database that identifies facilities, sites, or
places subject to environmental regulations or otherwise
of environmental interest.

A map layer depicting the location of TRI facilities as of
December 2020 was obtained from the FRS and overlaid

*HUC12s are subwatershed delineations in the National

Watershed Boundary Dataset. HUC12s are referenced by
their 12-digit Hydrologic Unit Code.


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Toxic Substances and Waste

with HUC12 boundaries to determine the number of TRI
sites per HUC12. Facilities reported as Inactive or Closed
were not included in HUC12 counts. Facilities in the
dataset with matching latitude-longitude coordinates were
assumed to be duplicates and only counted once.

HLJC12 values of toxic release and exposure potential were
derived from 2015-2019 RSEI scores reported by EPA for
TRI facilities. RSEI scores for all facilities nationwide were
downloaded in December 2020 from the EasvRSEI
database dashboard. Each RSEI score was assigned to a
HUC12 using the corresponding facility ID and the TRI map
layer used to determine TRI facility counts, as described
above. The RSEI scores were then summed to quantify the
total toxic release and exposure potential in each HUC12.

An example map displaying the RSEI scores for TRI facilities
is provided in Figure 2.

Figure 2. Map of Risk-Screening Environmental Indicators
(RSEI) scores for Toxic Release Inventory (TRI) sites in an
example HUC12.

Limitations

•	TRI site counts are provided to help users understand
and interpret the potential for toxic release and
exposure in a HUC12. High site counts do not mean
that toxic releases are occurring and/or harming a
population.

•	The RSEI scores used to quantify toxic release and
exposure potential are based on a model that has
been evaluated and refined by EPA researchers over
several years. However, all models are subject to error
and uncertainty. Refer to the EPA RSEI website for
more information on the limitations of the RSEI
model.

Links to Access Data and Additional Information
HUC12 indicator data can be accessed within the EPA
Restoration and Protection Screening (RPS) Tool, in
downloadable data files, or as a web service. Visit the EPA
RPS website for links to access the RPS Tool, HUC12
indicator database, and web service.

The TRI facility map layer used to calculate these
indicators can be accessed from the EPA Facility Registry

Service Geospatial Data Download website. The RSEI
model results used to estimate toxic release and exposure
potential can be accessed from the EPA EasyRSEI

Dashboard.

References

1EPA. 2021. What is the Toxics Release Inventory
Accessed October 29, 2021.

2EPA. 2021. Understanding RSEI Results. Accessed October

29,	2021.

3EPA. 2021. Introduction to the 2019 TRI National Analysis.
Accessed December 10, 2021.

4Brender, J., et al. 2011. Residential proximity to
environmental hazards and adverse health outcomes.
American Journal of Public Health. 101(1): S37-S52.

5Wilson, S., et al. 2012. Assessment of the distribution of
toxic release inventory facilities in metropolitan
Charleston: an environmental justice case study. American
Journal of Public Health. 102(10): 1974-1980.

6EI!iott, M. 2004. Environmental justice: frequency and
severity of US chemical industry accidents and the
socioeconomic status of surrounding communities.

Journal of Epidemiology & Community Health. 58(1): 24-

30.

7Luo, J., et al. 2011. Environmental Carcinogen Releases
and Lung Cancer Mortality in Rural-Urban Areas of the
United States. The Journal of Rural Health. 27(4), 342-349.

8Kershaw, S., et al. 2013. Identifying inequitable exposure
to toxic air pollution in racialized and low-income
neighbourhoods to support pollution prevention.
Geospatial health. 7(2): 265-278.

TRI Facility
2015-2019 RSEI Score
<8> 1-500
® 501 - 2000
® 2001-5000
0 5001 -15000


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