POLLUTION LOCATOR|Calculating Trends in Reported TRI Releases

Scorecard calculates trends in chemical releases and waste management from the current reporting year back to 1988, the first reliable year of TRI data. EPA's Toxics Release Inventory has evolved over time as reporting obligations have been extended to new polluting sectors, the universe of chemicals covered by TRI has changed, and new types of waste management information have been required. All these changes impact efforts to use TRI to profile trends in chemical releases or waste generation over time. Scorecard's trend calculation methods adopt the following approaches to addressing these changes:

TREND CALCULATIONS INCLUDE ALL INDUSTRIAL SECTORS CURRENTLY REQUIRED TO REPORT TO TRI
The TRI program has undergone two significant expansions:
1) beginning in 1994, federal facilities were required to report their releases and waste management practices,
2) beginning in 1998, seven new industries were required to report their releases and waste management practices. The addition of the mining and electricity generation sectors are particularly important, because these facilities tend to report very large releases.

Scorecard calculates time trends in TRI release and waste management categories by counting reports from all industrial sectors currently required to report to TRI. In contrast, EPA calculates TRI trends by counting reports from only the "original" industries covered by TRI in 1988. Both approaches are defensible, but produce dramatically different results. Because of the large increase in reported releases from mining and electricity generation sectors, Scorecard's calculations of trends in areas containing such facilities indicate substantial increases in pollution since 1988. These increases may be overstated, since pre-1998 releases from the "new" sectors are not included in historical TRI data (and there may have been decreases in releases from the "new" sectors over time). EPA's alternative approach of calculating trends by focusing only on "original" industries typically results in substantial decreases over time. These decreases, however, may not accurately reflect real chemical release trends, because they ignore reports from the "new" sectors which are now known to be responsible for about 75% of total TRI releases.

TREND CALCULATIONS INCLUDE ALL TRI CHEMICALS CURRENTLY COVERED BY TRI
The TRI list has undergone continuous revisions since it was originally established in 1986. EPA has deleted some chemicals and added others, changing the universe of substances covered by TRI reporting requirements.

Scorecard calculates time trends in TRI release and waste management categories by counting only those TRI chemicals that are listed in the current reporting year. Scorecard does not count a chemical if it has been dropped from the TRI list over the trend time period. In contrast, EPA calculates TRI trends by counting reports from only listed chemicals that have been reportable since 1988. Both approaches are defensible, but produce different results. Scorecard calculates trends in this way to avoid overstating the magnitude of changes in TRI releases over time. Several high volumne, low toxicity compounds have been delisted from TRI since 1988. Because they have been delisted, TRI releases can appear to have substantially decreased over time, when in fact these chemicals are still released in very large quantities (but are just no longer reportable to TRI).

Note: Scorecard's trend calculation method can generate discrepancies in the trend apparent in a TRI Data Summary for an area, compared to Scorecard's calculated percent increase or decrease for that area on trend detail pages. The TRI Data Summary table includes all chemicals that were subject to TRI reporting in a given year; trend detail calculations cover only chemicals subject to TRI in the current reporting year.

TREND CALCULATIONS FOR SOME WASTE MANAGEMENT CATEGORIES ARE NOT AVAILABLE PRIOR TO 1991
With the passage of the Pollution Prevention Act in 1991, TRI reporting requirements were expanded to include a variety of specific waste management categories(e.g., amount recycled or combusted for energy recovery). Trend calculations for these categories are only provided from the current reporting year back to 1991, the first year these data became available.