THREAT TO DESIRED LEVEL OF PROTECTION

Political judgment

All human activity has some impact on the environment. The question is: What is an acceptable impact and what impacts need to be prevented or miti­gated? Clearly this is a political question that requires broad community participation rather than a scientific question, given that the scientific evi­dence is inconclusive and the question of acceptability is a value judgment.

Definitions of the precautionary principle restrict precautionary measures to situations where the potential harm is 'serious and irre­versible' or 'unacceptable' or 'transgenerational' or 'global' or 'signifi­cant', as in 'significant reduction in biological diversity'. But most of these terms cannot be quantified scientifically or economically (de Sadeleer 2002: 163-5). For this reason the judgment should be made by a wide cross-section of the community, not by just a few experts.

'Judging what is an "acceptable" level of risk for society is an emi­nently political responsibility' (EC 2000a: 4). This is recognised by the EC (2000a: 8) definition of the precautionary principle, which states:

The precautionary principle applies where scientific evidence is insufficient, inconclusive or uncertain and preliminary scientific evaluation indicates that there are reasonable grounds for concern that the potentially dangerous effects on the environment, human, animal or plant health may be inconsistent with the high level of pro­tection chosen by the EU [emphasis added].

According to the World Trade Organization (WTO), each nation should be able to decide for itself the level of environmental and health protection which is appropriate, even if this means that in applying the precau­tionary principle it adopts a level of protection that is higher than required by international standards and guidelines (cited in EC 2000a: 11). Threats not only to present generations but to future generations must be considered:

It is not the existence of risk in itself that is the challenge, but the dis­tribution of risk and control of it.

Scientific judgments

Uncertainty may not only relate to the probability of a serious event occurring; it may also relate to how serious the consequences might be. For example, there is a general scientific consensus that global warming will occur if greenhouse gas emissions are not reduced, but the conse­quences of this are uncertain. There is no scientific consensus about the scope or rapidity of sea level rise or its consequences. There is even less consensus about the impacts in particular parts of the world (de Sadeleer 2002: 162).

Even if the potential consequences could be determined, their signif­icance will vary from person to person depending on, amongst other things, how they themselves will be affected; how resilient they believe nature to be; and how important environmental values are to them. Judgments about whether potential harm will be serious and irreversible will also vary between scientists, because such judgments include issues of the value of the area or species under threat, and of the time-span for reversibility to be considered feasible.

The impact of a particular activity or product may be small on its own but the impact of many such products and activities has also to be considered, both in terms of their cumulative impact and also the way various impacts interrelate. What may begin as a small impact may con­tribute to a major disturbance:

Economists call this phenomenon the 'tyranny of small decisions' because of the perverse effects that may result from a large number of micro-decisions that individually have no importance for environ­mental protection but which, taken together, give rise to considerable damage.

Guidelines

Adrian Deville and Ronnie Harding (1997: 26) suggest the following types of threats are widely regarded as serious or undesirable:

• Loss of species

• Loss of biodiversity (including species, genetic and ecosystem diversity)

• Damage to ecological processes

• Contamination of soils, water bodies and food chains

• Introduction of 'exotic' organisms to ecosystems

• Releases of 'new' chemicals.

'Irreversibility' is another term often used to decide if the precautionary principle should be triggered. It 'is usually defined as involving environ­mental resources that cannot be replaced, or which could be restored, but only in the long term or at great expense' (Dovers & Handmer 1999: 172). Whether the potential harm is reversible or not may be uncertain or dis­puted, and the issue of whether it can be reversed in the short term at a reasonable cost is a value-laden judgment.

Irreversibility may not be seen as a bad thing if that which cannot be reversed is not thought to be important. The loss of a particular insect, although irreversible, may not seem to be particularly serious, particu­larly if the activity that will result in its loss brings many benefits with it. For this reason many definitions specify that damage should be 'serious and irreversible' to trigger the precautionary principle. However, serious damage, such as an oil spill, may be reversible, but not before a great deal of harm is done, so some definitions specify that harm should be either 'serious or irreversible'.

One thing that should be noted is the lopsided nature of reversibility with respect to policy decisions. The decision to conserve an area and not go ahead with a development can usually be reversed at a later date. However, the decision to go ahead with a development is usually irre­versible once the development takes place.

The Louisville Charter for Safer Chemicals (Myers et al. 2005: 4) out­lines conditions for application of the precautionary principle with respect to chemicals:

1. Credible evidence that a synthetic chemical can cause biological changes that are known to result in unintended harmful out­comes in some cases.

2. The presence of such a chemical where it does not belong and where it can cause damage to biological systems (such as human bodies).