GCI TECH NOTES ©

In 1991, EPA released the "BIF Regulations". As part of those regulations, EPA established ambient impact limits for the BIF list of ten metals. As we prepare to review the next round of EPA regulations on thermal treatment facilities, it may be worth reviewing the 1992 emission rates for metals from cement kilns as compared with the BIF limits and other previously established ambient criteria. Prior to the BIF regulations, state air agencies frequently used American Council of Government and Industrial Hygienists (ACGIH) time weighted average (TWA) limits to establish ambient impact limits. It was common practice to divide the ACGIH TWA by ten to conservatively set an ambient impact limit. It should also be noted that ACGIH TWA limits were designed to conservatively protect workers in a forty hour per week, constant exposure environment, over forty years to levels judged to have no negative health impact.

Graphs 1 through 5 present ambient impact levels from 33 cement plants tested during the 1992 round of BIF tests. Also displayed is the BIF limit and the ACGIH TWA limit divided by ten. Bear in mind that the cement plant data represents "worst case operating conditions" and metal spiking. The limits on Graph 4 are for hexavalent chromium while the emissions data represents total chromium. For those plants that tested hexavalent chromium emissions, levels were generally non-detects and about 100 times less than total chromium emissions.

Given the information presented in those graphs, the following questions must be asked:

• How can EPA justify lowering limits based on concerns for human health and safety?
• How does EPA justify the continuing risk to human health and safety incurred by clearly unnecessary stack sampling and metal spiking?
• On what basis does EPA continue to utilize the widely discredited linear models for risk extrapolation for both carcinogenic and non-carcinogenic toxins?
• When will EPA be held morally and legally responsible for justifying regulations based on the net impact to human health and safety?

Graph 1

Graph 2

Graph 3

Graph 4

Graph 5