Comment and Reply

Letters to the Editor

Letters to the Editor: Comment and Reply

Threshold Inventory Interpretation Methodology: A Case Study of Three Juice Container Systems L.M. HOGAN, R.T. B~:AL, R.G. HUNT

Int. J. L C A 1(3):159-167 (1996)

Comment Letter to the Editor, Int. J. LCA Dear Profi Kl6p//bl; In their threshold inventory interpretation method (TIIM), Ho(;aN et al. (I 996) address an important property of toxic effects; the existence of a threshold. Unfortunately, the proposed impact evaluation method discounts a large part of the information contained in the life cycle i,t ventory. The way TIIM disregards some emissions does not reflect the risk perceptions expressed by the public and does not agree with what we know about thresholds. Hence, I am skeptical that TII M will bc publicly accepted as impact assessment nletbod. HO(;AN et al. propose to count only emissions of criteria air pollutants that occur in areas not in attaimnent with the Clean Air Act

(CAA) and emissions of acid precursor emissions in regions where acid rain has been identified to be a problem. Ho(;,\N et al. therefi)re negate any concern about air emissions of pollutants that are not criteria air pollutants as defined by CAA or that occur in areas in compliance with the CAA's national ambient air quality standards (NAAQS). Their justi fica tion: "Health problems assocklted with

working levels of non-criteria pollutants have not been documented; thus, emissions of these substances have not generally been an issue of concern... " This statement is, in fact, incorrect. In addition to the seven criteria air pollutants, CAA regulates 189 hazardous air pollutants. The toxics release inventory lists 651 chemicals of concern. Many other pollutants have been identified to be hazardous in epidemiological or experimental studies. In addition, exposure to criteria air pollutants below the NAAQS may result in adverse health effects and in ecological damage. Enough scientific evidence has been accumulated to justify a lowering of the NAAQS for ozone and particulate matter, a step that EPA pursues only reluctantly because it results in significant political opposition and in high costs for the regulated community. In general, regulations are a poor indicator of environmental risks because they are the product of a political process dependent on the technical and economic feasibility of pollution control and the political strength and skill of various stakeholders. HOGANet al. also fail to recognize the nature of acid precipitation. Acid precipitation is a problem on a continental scale; clouds containing SO x and NO x travel hundreds of kilometers and affect distant regions. Studies have shown that sulfur dioxide emitted in the eastern US causes acid precipitation not only in Canada, but as far away as Great Britain and Scandinavia. Discarding acid emissions from locations that do not experience acidification themselves is highly problematic, because these emissions are likely to impact other areas.

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1 am critical of the impact matrix approach Ho(;AX et al. have chosen as a way of comparing different emissions. It does not separate minor and major environmental risks or distinguish between important or inconsequential contributions to these risks. A specific product may contribute significantly to an important environmental problem and at the same time cause only a minor contribution m another problem. The approach chosen in TIIM sets these two contributums equal. At least four of the six impact evaluation methods reviewed in the forthcoming paper by HrRT\VU:IIet al. {1997) are better suited to comparing LCIs: Swiss ecopoints, the Sustainable Process Index, the SETAC LCA impact evaluation, and the Environmental Priority System. In general, I faw~r the SETAC approach (FAvAet al. 1993), and, for toxic emissions, the proposal by GtIINI::Eand Hr[IuN(;S (1993). The qt, estion about threshold effects in human health and ecosystem impacts raised by Hoe;aN and colleagues is important and their paper provides a starting point for a necessary discussion. The use of legal standards and the fiat-out dismissal of insults below limits, however, are not justified by our current state of knowledge. Better ways of assessing the impact of toxic emisskms do exist. References F,wA, J., E Coxsou, R. D~!~ISON,K. DIC~:soN,T. MOlUN, B. VK;ON, eds. (1993): A Conceptual Framework for Life-Cycle Impact Assessment. Society of Environmental Toxicology and Chemistry, Pensacola, Florida Gt,NI::I-,j., R. HE0u.~(;s(1993): A Proposal for the Classification of Toxic Substances within the Framework of Life Cycle Assessment of Products. Chemospbere 26 (10):1925-1944 HERTWICH,E.G., W.S. PEASE,C.P. KOSHtAND(1997): Evaluating the Environmental Impact of Products and Production Processes A Comparison of Six Methods. Sci. Tot. Environm. (in press) HOGAN, L.M., R.T. BEat., R.G. HUNT (1996): Threshold Inventory Interpretation Methodology. Int. J. LCA 1 (3):159-167 -

Sincerely, Edgar G. Hertwich Energy and Resources Group University. of California 310 Barrows Hall Berkeley, CA 94720-3050, USA [email protected] phone +1-510-642-8853 fax +1-510-642-1085 Int. J. LCA 2 (2) 62 - 63 (1997) 9 ecomed publishers, D-86899 Landsberg, Germany