Precaution in Practice

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Precaution in Practice

presented at the Children with Leukaemia meeting “Powerlines and health”

National Exhibition Centre, Birmingham, 5 December 2002
M J O’Carroll

1. The problem

Concerns expressed by residents and the responses of the Electricity Supply Industry (ESI), NRPB and government indicate a conflict between their various perceptions of national needs and public safety.

Here I try to express key perceptions in the conflict in my own terms, aiming to avoid unreasonable perceptual bias and to seek common ground.

A reliable public electricity supply is needed for public quality of life, safety and economy.
A competitively priced electricity supply is needed for business and the national economy.
Success of the privatised ESI is politically and economically important to government. 
Overhead lines expose nearby residents to real and measurable physical effects (e.g. EMFs).
Overhead lines are much cheaper than underground cables.
Residential exposure brings potential risks of harm, perhaps firm risks.
Scientific evidence supporting (f) is in dispute, but cannot be dismissed.
The impact of such harm is unclear - the stronger evidence comes with smaller numbers.

The essence of the conflict is that, on the one hand, people, particularly children, have potentially fatal risks imposed on them for commercial and political reasons, and denied for the same reasons, while on the other hand, it would be unfair and against the public interest to burden the ESI with liability and cost on account of unproven possibilities of numerically small risks.

There are also concerns, from both sides, about precedents and wider issues of public safety and economic success. 

The following would seem to me to be unreasonable claims:

The evidence of potential harm is so weak it should be disregarded.
The evidence proves the harm beyond all reasonable doubt.
Exposures above some level (e.g. 0.4 μT) should be prohibited and removed.
All powerlines within some distance (e.g. 100 metres) of homes should be buried.
Safety must be guaranteed 100%.

There are other issues with powerlines, notably visual impact and property devaluation. This paper concentrates on health issues. Visual issues can interact with health issues, for example through the stress of financial impact, damage to quality of life, and a sense of injustice at an uncompensated imposition. However, I leave these aside, and concentrate on direct physical effects.

2. Risk

The Oxford English Dictionary is not very helpful in defining risk, which it does not clearly distinguish from hazard. Collins is clearer for contemporary use: the possibility of incurring misfortune or loss. Note that is a possibility, not a numerical probability, so risk is there a concept not a number. More technical definitions express risk as a probability or a likelihood, i.e. a number [1, 2]. However in business risk analysis “risk” may refer to the possibility, while likelihood is a separate factor. Generally we may say: a risk means a possibility of harm occurring.

In risk management circles, the idea of risk depends on more than an unreasoned possibility or pure fantasy. It needs to be a definite possibility. A better definition would be: 
a risk means a reasoned possibility of harm. 

The corresponding numerical-risk would be the probability of the harm happening, but I want to be careful to distinguish the two.

In the present case there is the question of a causal effect between the exposure and the harm. But the idea of cause is itself intrinsically imprecise and uncertain. So we have the (mere) possibility of a causal effect. If the possibility of causal effect is reasoned, then there is a risk of a causal effect, and hence a risk of a risk (of harm), which is still a risk, even if the cause is not firmly established.

The NRPB accepts that there is a possibility that EMFs cause cancer. But it does not accept there is a definite or established causal effect. Conventionally, agreeing a causal effect depends on (e.g. using the Bradford Hill guidelines) establishing both a statistical association and a plausible mechanism. 

So much depends on definitions. Sir Richard Doll [3] says “Personally, I interpret plausible to mean something that I should be prepared to believe”, whereas the OED gives “having a show of truth, reasonableness or worth”. The statistical association has been confirmed numerically though not accepted as causal. Mechanisms have not been accepted by NRPB, but evidence of potential mechanisms grows. How much evidence is needed to accept a reasoned possibility of a cause is a matter of opinion. NRPB is not convinced, and treats an unproven cause almost as a fantasy.

What is needed here is a graduated assessment of causation, rather than the yes/no approach of NRPB. This is where the California Department of Health tackles the job [4]. They introduce a “degree of certainty” of causation by EMFs, called “degree of confidence in causality” in an earlier draft. For childhood leukaemia all three assessors recorded a degree above 50%.

Note the term “Possible Risks” in the title. This acknowledges the situation that it is not generally agreed by all stakeholders that there is a causal effect. Similar terms have been used, such as uncertain hazards [5], phantom risk [6, 7] and virtual risk [8].

This class of possible risks, as some of the other names suggest, tends to be treated by the public authorities as suspect. California is an exception, bringing a rigour to the assessment. The UK seems to be frozen in the headlamps after the BSE-CJD affair, recognising the failure of political dismissal, but unsure how to develop a more inclusive approach. That is why the NRPB meeting is held today.

3. Uncertain hazards

Adams & Thompson [8] describe virtual risks as ranging “through speculations by ‘alternative’ specialists (e.g. various dietary theories of illness), popular fears (e.g. living under powerlines causes cancer), superstitions (e.g. ladders and black cats), to theological speculations (e.g. misfortune is punishment for sin)”.

They continue: “A few of these perceived risks persist in the face of refutation by conventional science, but it is the risks that conventional science cannot convincingly confirm or refute that cause the greatest difficulties for regulators such as the HSE. These risks are liberating in the sense that, if science cannot settle the issue, people are freed to argue from their established beliefs, convictions, prejudices and superstitions.”

The fear that “living under powerlines causes cancer”, at least in respect of childhood leukaemia, should be at the rational end of the range of “virtual fears”, with the benefit of California’s rigour. There should be a strong objective side to assessment. Adams & Thompson want to replace “objectivism” by “constructivism”, with a plurality of subjective views, but that is not to lose science or objectivity.

There should be a role for independent assessment, but not with an exclusive monopoly, as the NRPB seems to have. There are levels of independence, just as there are levels of uncertainty and plausibility in the state of evidence. Some limitations on independence may be structural.

In the UK we do need impartial advice and assessment of hazards. An expert advisory body is a good idea. I note Susan Greenfield's recent move to develop a more general scientific advisory group, with strict avoidance of government funding. There are difficulties in achieving high levels of independence, especially in government-appointed bodies, which may be staffed by career civil servants with a strong and long-term personal career interest. Even bodies drawing from external experts acting part-time may benefit from variation of personnel and from supplementation by non-expert and public representatives - I am thinking of the Phillips Report on BSE and the earlier supplementation of SEAC which took place in the mid 1990s.

In my view NRPB, and AGNIR in particular, has demonstrated an inclination to dismiss concerns, perhaps over-zealously to avoid a health scare, although such zeal has historically been counter- productive. My critique [9] of the Doll II Report gave chapter and verse to show distortive language and spin to that effect. Alasdair Philips's critique [10, 11] also illustrates the point. 

Three key issues which NRPB seems to overlook are human variability, information physics and precaution. In contrast the Stewart Report [12] on mobile phones, structurally more independent than NRPB standing committees, was more aware of these issues and criticised NRPB.

The issue of human variability is eloquently described by Alasdair Philips, with a commendably grand concept of modern epidemiology as "safety for the susceptible". NRPB, by considering impacts only when diluted in the general population, are able to bolster their dismissive approach. They do seem to be looking for dismissal and not looking to identify impacts.

The issue of information physics goes beyond the very limited approach of NRPB (to non-ionising fields) which seems to be confined to coarse energy effects, either through induced macroscopic currents and thermal effects, which forms the sole basis of their guidance, or through the direct-hit effect on DNA at the molecular level, which enables NRPB to dismiss non-ionising radiation as "subtle effects". On the other hand information effects relate only to the energy required to store, transmit or interfere with information, which may be very low in terms of, for example, cell signalling or release of radicals from a weakly bonded caged configuration, as indicated in published research. The term "signal effects" may also be used, as mentioned by Alasdair Philips and Swiss Re. On this issue, NRPB and AGNIR seem to be out of touch with modern information physics and limited by their old- fashioned view.

The key stages of assessing an identified uncertain hazard are:
(a) confidence in causation (California report) or credibility of cause [13];
(b) the statistical incidence or likelihood of the risk;
(c) the impact of the risk.
It is possible to take all of these into account in assessing risk and considering policy responses. So far, the NRPB has avoided such an approach.

The HSE [14] has acknowledged uncertainty, and has tried to classify it by type, but has not got to grips with assessing it. Recognising the importance of historical failures to respond to uncertain hazards, an EU report [15] sets out 12 “late lessons”. The first is “respond to ignorance as well as uncertainty”, with its accompanying definitions and analysis. The EU report is a rich resource.

4. Precaution

The choice of definition of precaution is not vital in practice, though there are legal considerations. Stewart [12] refers to EU and WHO sources and quotes a ruling of the European Court of Justice which concluded: “Where there is uncertainty as to the existence or extent of risks to human health, the Commission may take protective measures without having to wait until the reality or seriousness of those risks becomes apparent.” Note the reference to “existence or extent”. A key principle is that the measures should be proportionate to the risk, though Adams & Thompson [8] refer to Edwards v. NCB 1949 sanctioning “gross disproportion” of measures above risk.

The UK approach is reflected in a written response [16] to Mr Alex Carlisle’s question “To ask the SoS for Health if she will make it her policy to encourage the enactment of a prudent avoidance policy with regard to electrical powerline work …”: Mr Sackville: “…. On the basis of present evidence, the two bodies [NRPB and COMARE] have not recommended the adoption of a policy of prudent avoidance. …”

More recently correspondence [11] from Sir Richard Doll shows the AGNIR has not considered precautionary policy. Nevertheless, ministers have dismissed precaution on the basis that "NRPB does not recommend" it. Further, this has been used to block any discretion on the part of local authorities. The main test comes with planning applications to build new houses under existing powerlines. Local authorities attempting to adopt a precautionary policy have been faced with National Grid's legal team objecting at public inquiries, with the effect that acknowledgement of a health problem and a precautionary approach is expunged before or by Secretary of State's decision. I have summary notes of cases at Calderdale, Lincoln, Hambleton and Middlesbrough

The NRPB has, at least through published opinion of its officers, discouraged precaution [17]. The article presents fair arguments but they are selected to argue against the position of prudent avoidance adopted in Sweden. Other arguments and a different emphasis could be made. Nevertheless the article stops short of rejecting prudent avoidance. Rather it presents arguments to encourage readers to the opposing view, then leaves them to make up their own minds. Other articles have been more scathing, suggesting prudent avoidance means avoidance at all costs.

A test policy: other things being equal, exposure will be avoided has been vigorously resisted by the NGC in this country and the ESB in Ireland. I had put a similar question to Sir Richard Doll at a conference in 1995, with reference to powerlines to be built near a school, and he indicated he would support such a policy. He also mentioned the Chinese wall he observes between scientific advice and policy consideration.

5. Practical options

The NCRP, an American counterpart to the NRPB, appointed Scientific Committee 89-3 chaired by Professor Ross Adey, which after nine years on the EMF problem produced a draft report [18] in 1995. It is a very thorough report which addresses the question of precaution and makes recommendations. Unfortunately the report was blocked in its formal approval stages which included political and industrial interests. It is worth re-visiting however, as abbreviated below.

Four options were considered for the existing EM environment:

Option 1. No recommendation.
Option 2. Exposure guideline of 0.2 μT and 10 V/m.
Option 3. Exposure guideline of 1 μT and 100 V/m.
Option 4. The ALARA concept (as low as reasonably achievable). 

The conclusion was to adopt Option 4 allowing an ALARA guideline to be progressively implemented over a ten year period.

For future developments, the Committee recommended that

(1) new schools etc. should not be built where ambient fields exceed 0.2 μT,
(2) new housing should not be built under existing HV lines or where ambient fields exceed 0.2 μT for longer than two hours daily,
(3) new powerlines would not be built where they would produce fields exceeding 0.2 μT in existing houses,
(4) in new offices etc. aim to reduce intermittent and ambient fields to 0.2 μT.

In my view it is important that any such measures should be guidelines and not firm limits. Guidelines could be used as a basis for requiring good reasons for, rather than prohibiting, exceeding the exposures, and they could be incorporated in national planning guidance.

The prospect of people choosing to live under powerlines, even if the authorities agreed there was a health risk, should not be ignored. There are many benefits from staying in the same house, such as community and schooling, which may lead people to prefer to take the small risk, as has happened where houses have natural radon levels presenting a risk. The introduction of formal guidance is however likely to have an effect on house prices. Questions arise on compensation, or assistance with moving or offers of purchase in extreme cases.

It is necessary to consider cost. The cost of burying all National Grid’s 4,000 route km would be some £40 billion. This is not contemplated. The cost of full implementation of guidelines such as these might be of the order of £4 billion over ten years. That compares with roughly half a billion pounds annual profit of National Grid and with a turnover of the electricity market in England and Wales of the order of £15 billion or wholesale value around £5 billion per year. Full implementation would add to the price of electricity significantly, but not impossibly. These things would need considering against the damage to industrial competitiveness and impact on the community, and they would be major considerations.

John Stather [17] gives an indicative cost-benefit analysis, with exposure reduction measures valued roughly from £200,000 to tens of millions of pounds per case of leukaemia avoided. That is based on a relative risk of 2.7 as found in the association with residential exposures to fields above 0.2 μT. This takes no account of benefits other than for cancer. These are typical rates of investment in risk reduction and it is interesting to note NRPB’s own theoretical evaluation for occupational exposure to (ionising) radiation of £100,000 to £1.7m per nominal life saved (1987 values). 

More immediate and simpler steps, and more easily justified, would include:

(1) government and the NRPB to adopt a more open and less denialist approach;
(2) guidance on the no-cost policy of, other things being equal, avoiding exposure;
(3) allowing discretion to local authorities to adopt precautionary planning policies;
(4) clearer and better balanced advice to the public, e.g. on reducing their exposures;
(5) reflection of the concerns and doubts in compensation for new projects.

The EU principle of internalising the cost of environmental damage at the planning stage of projects would guide developers in choosing options.

6. Conclusions

The approach to risk, and especially uncertain hazards, is under discussion in the EU and the UK, in the wake of the BSE affair, with a view to becoming more pluralistic, consultative and flexible.

The power industry, and with it the NRPB, still holds out in resisting a more open approach and in contemplating precaution. They seem to be gripped by a reverse-health-scare.

It is timely however, as research progresses and more is understood about possible mechanisms and risks, to prepare for the possibility of precaution in the power industry. This would be a natural part of business risk management. Possible measures, costs and consequences should be considered. 

Government equally has a duty to prepare. While it will need to assess its actions carefully to avoid precipitating an over-reaction, it will need to make considerations, and hopefully would do so openly. Some ideas of possible precautionary measures are mentioned here in order to promote the discussion rather than to offer the full solution.


[1] Royal Society 1992, Risk: analysis, perception and management, Royal Society, London.
[2] Royal Society 1997, Science, Policy and Risk Royal Society, London.
[3] Sir Richard Doll, private communication, 20.12.95.
[4] California Department of Health, An Evaluation of the Possible Risks from EMFs from Powerlines (etc.), 2002.
[5] B Knave et al, Guiding Principles and Guidance Values for Occupational Exposure Limits to EMFs (0-300 GHz), WHO, 1995.
[6] C Brauner, Electrosmog - a phantom risk, Swiss Re, 1995.
[7] K R Foster et al, Phantom Risk: Scientific Inference and the Law, MIT Press 1993.
[8] J Adams and M Thompson, Taking Account of Societal Concerns about Risk: Framing the Problem, HSE, 2002.
[9] M J O’Carroll, Summary of NRPB EMF report, March 2001.
[10] A Philips, Doll II - ELF EMFs and the Risk of Cancer, Commentary, 2001.
[11] Electromagnetic Hazard & Therapy, Vol. 12, No. 1, pages 1 and 3, 2001.
[12] W Stewart, IEGMP Report, Mobile Phones and Health, NRPB, 2000.
[13] M J O’Carroll, Risk communication: Mobile Telephones and Health, City & Financial Conference, London 6-7 June 2001.
[14] J Le Guen, Reducing Risks, Protecting People Discussion Document, HSE, 1999.
[15] European Environment Agency, Late lessons from early warnings: the precautionary principle 1896 - 2000, Environmental Issue Report No. 22, 2001.
[16] Hansard 21.2.94
[17] J Stather, EMFs, risks and cost-benefit analysis, Radiological Protection Bulletin No 186 of Feb 1997.
[18] NCRP Draft Recommendations on EMF Exposure Guidelines, Microwave News vol. XV No. 4, July/Aug 1995.

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