"I think this is more than a common cold, doctor..."

For the study, the surrounding area was separated into four zones, each a kilometre wide, radiating up to four kilometres from the landfill site. Burngreave lies mostly in zone 2.

Within one kilometre of the site (zone 1), reported levels of bronchitis are more than twice those for Sheffield as a whole. Levels of chronic obstructed airways disease (COAD) are two and a half times higher.

Bias ruled out?

Such results seem to point to the landfill site as the source of these problems. But Dr Jeremy Wight, Director of Public Health at North Sheffield Primary Care Trust (NPCT), who commissioned the study, provides two other possible explanations: other environmental causes of the symptoms, and what the study terms 'reporting bias' – that the rise in self-reported symptoms was caused by heightened awareness in the community (as described in our main story: Fury over Parkwood Health Study).

As a result, the NPCT cannot confirm any connection between the site and local health problems, and proposes further research which would take another year.

But the study itself offers several reasons why the 'reporting bias' explanation is unlikely. One is the distinct difference in levels of symptoms reported in study zones 1 and 2. For example, bronchitis symptoms are reported at twice the level in zone 1 than they are in zone 2. "It would be odd if reporting bias were to affect [people in zone 2] substantially less than people living in the innermost zone," comments the report.

Some symptoms are reported less in zone 1 than further away. People living further from the site reported more symptoms of liver disease than those close to the site. If there was no reporting bias for these symptoms, then why assume there is reporting bias for the others?

Finally, the reporting pattern for bronchitis and COAD symptoms is supported by the results of a previous survey (see Top of the Coughs issue 17, November 2001). In addition, the survey questionnaire was designed to take account of, and reduce, the possibility of recording bias.

I put it to Dr Wight that these arguments effectively ruled out the 'reporting bias' explanation. He told me that the study does not rule out this explanation, and that I would be wrong to report that it did. Brian Wilson, long-time campaigner for the site’s closure described reporting bias as "a polite way of saying victims are lying."

No intention to prove anything

We were told in February that a survey was "to be carried out to see if the site is damaging health" (Study examines landfill effects on health issue 29, March 2003). Now it appears that the survey results could never prove anything because of the possibility of ‘reporting bias’. It is not surprising that local people feel betrayed. They completed questionnaires in good faith and are now told that their answers cannot be believed. Instead they are told to wait for further studies by experts, while the evidence in the Report appears to confirm what their daily experience tells them: their health is in danger.

Do landfill sites cause ill health?

Part of the Report consists of a review conducted by the Chemical Incident Response Service of previous studies into links between landfill sites and adverse affects on the health of local residents.

The review said studies were inconclusive. However the Messenger is aware of various studies which strongly indicate links:
In Hamilton, Ontario, a study of people who lived and/or worked near an industrial dump revealed significantly elevated rates of bronchitis, breathing difficulties, coughs, skin rashes, arthritis, heart problems (angina and heart attacks), muscle weakness, tremors, cramps, headaches, dizziness, lethargy, balance problems and mood symptoms, compared with populations living further from the site (Hertzman, C. et al., "Upper Ottawa Street Landfill Site Health Study," Environmental Health Perspectives, vol. 75, 1987, pp 173-195).

An American study of 7 waste disposal sites showed increased incidence of dermatitis, respiratory irritation, neurologic symptoms and pancreatic cancer in nearby populations (Barry L. Johnson, Asst. Surgeon General, testimony before the Subcommittee on Superfund, Recycling, and Solid Waste Management, US Senate, May 6, 1993, citing various studies).

In Lowell, Massacchusetts, a group of 1049 people living 1200 feet from a chemical waste dump reported more complaints of wheezing, shortness of breath, coughs, persistent colds, irregular heartbeats, constant fatigue and bowel dysfunction, compared to people living 2 and 3 times as far from the dump. The study examined the possibility of recall bias and concluded that this did not explain the findings (Ozonoff et al., "Health Problems Reported by Residents of a Neighborhood Contaminated by a Hazardous Waste Facility," American Journal of Industrial Medicine, vol. 11, 1987, pp 581-597).

Of course, we don’t know whether what was dumped at these sites was similar to what is dumped at Parkwood, because we are not told precisely what is being dumped at Parkwood.

The study ignores the analysis of dust from houses near the site in October 2001 which showed the presence of cadmium and arsenic, which can cause lung damage and sore throats at low levels (Dumped on us - everyone’s toxic waste issue 19, February 2002). Cadmium is present in the incinerator fly ash dumped at Parkwood, brought from Edmonton, north London. This appears to indicate a direct connection between the site and reported symptoms.

As the Report was released, Viridor Waste Management, the site’s owners and operators, issued a statement quoting the Report’s conclusion that there are ‘no firm grounds’ to conclude that the health of those living near the site is affected by it. Viridor bought Parkwood landfill for £20.6 million earlier this year.

What happens next?

Parkwood Landfill Action Group has called for an immediate stop to toxic waste dumping. In response, Sheffield City Council’s Cross Party Working Group on Parkwood Landfill (which reconvened on 20 November) asked the Environment Agency to process the re-licensing of the site as quickly as possible, so that toxic waste dumping could be banned.

The NPCT is to examine local doctors' records to see if symptoms reported in the study match up with people's medical records. If they do, this will rule out reporting bias.

Local residents say other factors, such as wind and geography, should have been taken into account in the study. Dr Wight told the Council’s Working Group that further research will analyse these factors and the study data will be re-analysed in the light of them.

Closing the site

Only the Environment Agency can order Viridor to close the site. The Messenger put it to Agency representatives that the NPCT’s further research might well rule out reporting bias and analysis of wind and geographical data might reinforce the results of the study. In that case, would they order the closure of the site? They responded only that they would take further advice in response to such findings.

Only if it were proved that substances coming off the site were actually causing diseases would the Agency close the site. I asked them whether any kind of statistical data would ever be sufficient to convince them that the site should be closed. Again, they said only that they would take further advice in response to such findings.

Agency representatives told the Council’s Working Group that they could only close the site if it was proved beyond reasonable doubt that it was damaging people’s health. But Councillor Martin Davis pointed out that the law requires the Agency to act if a site is 'likely to cause' injury to health.

Analysis

Dr Wight continues to reassure critics that North Sheffield PCT will not hesitate to seek the closure of the landfill operation should any link between it and the ill health of local residents be scientifically proven. Neither I nor anyone else who is critical of the work and presentation of the Health Impact Assessment Survey doubt the sincerity of this commitment. The problem is that such agencies of the State cannot accept what ordinary people say about themselves as scientifically valid.

Dr Wight tells us that ordinary people who filled in the survey questionnaire did so honestly, but their answers may have been influenced by thoughts of which they were not aware, because ordinary people don’t consider carefully whether the answers they give are really true. Self-reported data can only ever be regarded as indicating that a problem might exist.

Once the existence of the problem has been established, scientific truth may then be found by looking behind the apparent superficial problem of self-reported symptoms for evidence that only experts can find and interpret. This is the normal way in which scientific knowledge is constructed by agencies of the State, and Dr Wight and the PCT cannot proceed in any other fashion, because of their institutional position.

But can the planned further scientific investigations deliver the certainty we need? In practice, science rarely gives us definite answers. It only provides probabilities. If GPs’ records confirm that there was no reporting bias in the study, and meteorological studies and geographical studies show that symptoms occur downwind of the site, then the probability that pollution from the site is the cause of the symptoms will have increased. But probability is all we will get.

In the absence of scientific certainty, the landfill operators will continue to assert that nothing has been proved against the site and the way it is operated.

Over the last few years the Messenger has heard numerous reports from those who live close to Parkwood that there are times when they children cannot play outside their homes, because of dust and smells which choke them and irritate their airways. They feel ill. They report clear signs of effects on their health. They observe that the dust and smell is carried on winds crossing the landfill site. Their conclusions are clear and logical, because they are based on the observed relationship between a number of events that they experience. It can be said that, in Shirecliffe and adjacent areas, it is common knowledge that the site affects the health of people living near it. But the knowledge of the State is opposed to common knowledge, and by default supports the private company that operates the site.

While the uncertainties of environmental science are posed as a superior form of knowledge to logical conclusions drawn from the experience of ordinary people, no precautions will be taken to protect the health of those living near the landfill site.

The full Health Impact Assessment Survey Report will be made available on the Sheffield NHS website at www.sheffield.nhs.uk.