OP News : August 2006

Study of neuropsychological and psychiatric functioning among OP exposed sheepdippers

Sarah Mackenzie Ross, University College London, was awarded funding from DEFRA in 2004 to undertake the above study. Her team have spent the last 2 years identifying and recruiting suitable study participants. They have now commenced phase 2 of the study which involves visiting farmers in their homes in order to carry out a clinical examination. The examination involves psychological testing (memory and problem-solving tests) followed by an interview about work/exposure history and emotional well-being. The team are recruiting farmers from the North and South West of England. Julia Britton is based at Exeter University and is responsible for conducting the study in the South West and Kelly Abraham is based in the North of England.

This study differs from those that have been commissioned before in that (1) it involves detailed clinical examinations, rather than a postal survey (2) farmers who have retired or reduced their workload are being recruited in addition to working farmers (3) the research team are investigating factors which may render some individuals more vulnerable to the effects of organophosphates than others. Sarah has commissioned Professor Furlong in the USA to measure blood levels of an enzyme (PON1) which plays a major role in the breakdown and detoxification of pesticides

Sarah Mackenzie Ross is meeting DEFRA and the VMD on the 15th September 2006 to establish whether they will continue to fund this study.

Julia Britton, School of Psychology, University of Exeter, Washington Singer Laboratories, Perry Road, Exeter EX4 4QG. Tel: 07909661609. Email: J.H.Britton at exeter dot ac dot uk.

Kelly Abraham, Tel: 01756 790 686. Email: kelly.abraham at ucl dot ac dot uk.

Ill health following reported exposure to contaminated air on commercial aircraft

Over the last year, Sarah Mackenzie Ross and colleagues from UCL have examined 27 self-selected commercial airline pilots who had reported exposure to contaminated air to union officials. They underwent neuropsychological and adult mental health assessment. In March 2006, the Secretariat to the Committee on Toxicity (COT) asked Sarah to prepare a report describing the results of these assessments.

Cabin air on commercial aircraft is supplied from the engines or auxiliary power unit. The air, which is unfiltered and known as "bleed air", is sometimes contaminated with hydraulic fluids, synthetic jet engine oils and combusted or pyrolised materials (e.g. carbon monoxide, phosphorus oxides, aldehydes). These oils contain a large number of chemicals which can cause irritation, skin sensitization and neurotoxicity (e.g. the organophosphate tricresyl phosphate (TCP). All pilots, bar one, reported chronic health problems including fatigue, sleep difficulties, fluctuating gastro-intestinal problems, numbness and tingling in fingers and toes, memory and word-finding difficulties.

Pilots completed an extensive battery of more than 30 neuropsychological tests. There was no evidence of global intellectual decline, language or perceptual deficits in this cohort. Indeed, pilots were intact on the vast majority of tests. However, there was evidence of under-functioning on tests associated with psychomotor speed, executive functioning and attention.

These findings are of obvious concern; especially as they pose a risk to flight safety and may be magnified under particular working conditions. Indeed, some of the pilots examined reported alarming cognitive failures following exposure to contaminated air such as: being unable to retain or confusing numerical data and information provided by Air Traffic Control regarding heading, altitude, speed; completing tasks in the incorrect sequence; setting the wrong cleared level for the aircraft to climb or descend; taking off with the wrong flap setting; being able to hear air traffic control or colleagues talking to them, but being unable to respond; being unable to recall important matters such as whether the undercarriage has been raised or lowered. Twenty out of the full sample of twenty seven pilots underwent fat and blood analysis and were found to have higher than population average levels of one or more volatile organic compounds.

Sarah Mackenzie Ross concluded that the cognitive deficits identified in this cohort of pilots can not be attributed to factors such as mood disorder, anxiety disorder, malingering or chance. Whilst the evidence available does not enable her to draw firm conclusions regarding a causal link with exposure to contaminated air, the neuropsychological deficits found in this study and the physical symptoms reported by pilots resemble those found in the literature on exposure to organophosphates and solvents. Given the scientific uncertainty regarding the potential hazards of inhalation of pyrolised engine oil, it is Sarah's opinion that further research into the full range of health effects from inhalation of heated or pyrolised synthetic jet oils is definitely warranted.

Sarah was invited to attend an initial meeting of COT on the 11th July 2006 to answer questions about her report. COT have since sent her report for external review COT have yet to form an opinion regarding the health effects of contaminated air and will meet again in December 2006.

Legacy

In July OPIN was approached by a solicitor whose client, a Scottish farmer, wished to support the work carried out by OPIN for the last fifteen years by leaving us a legacy in his will. We put the solicitor in touch with the Joseph Rowntree Charitable Trust which has supported OPIN with funding. After discussions with the Trust it was decided that a committee should be formed to administer the legacy for appropriate purposes, one of which might be to support original scientific research. The following experts all readily agreed to serve on the committee: Lord Tyler of Linkinhorne; Professor Andrew Watterson, Occupational and Environmental Health Research Group, University of Stirling; Dr Sarah Mackenzie Ross, clinical neuropsychologist, University College, London; Liz Charles, solicitor, Hay-on-Wye; Dr Stephen Hodges, Department of Hepatology, University College, London; Dr John Cherrie, Institute of Occupational Medicine, Edinburgh; Peter Bright, solicitor, Plymouth; Professor Clement Furlong, Research Professor of Genome Sciences and of Medicine, University of Washington. We are extremely grateful for this generous decision by an anonymous friend, especially as there are important advances being made in the field of OP research and extra funding is always needed.

Links between OP victims

It has repeatedly been drawn to our attention that recognised symptoms occur between different groups of people, for example the illnesses suffered by people who served in the first Gulf war and sheep farmers, and more recently the effects experienced by pilots who have been flying certain aircraft (see the MacKenzie Ross evidence to COT, cited earlier).

We know also that the men who worked at the nerve gas pilot production plant at Nancekuke in Cornwall in the 1950-1960s suffered similar symptoms, and recently an article in New Scientist describes the effects on veterans of chemical weapons tests at Porton Down as being "strikingly similar" to those of the 1991 Gulf war veterans (Military Test Veterans Suffer Gulf War Effects, New Scientist 29 July 2006). OPIN has documentary evidence of the repeated widespread use of OP pesticides in the 1991 Gulf war, on tents and latrines, hospital units, canteens and equipment. When the UK-supplied stores of OPs were used up the Hygiene units were told to buy in from local sources: the instructions were in Arabic.

OPIN believes that it is crucial that these different cases be looked at as examples of similar chemicals, used under different circumstances, causing similar neurological and neuropsychological symptoms (see Health and Safety Executive Guidance Note MS17. See also a scientific monograph published by the Stockholm International Peace Research Institute, which states that "all the organophosphorus compounds are structurally and functionally closely related to each other". It is speaking of OP chemical weapons, pesticides and solvents, in the chapter headed Delayed Lesions caused by OP agents).

OPIN was recently visited by an OP-affected pilot who has been forced to retire due to fatigue, stress and confusion. His story is alarming as colleagues who are similarly affected are still flying because they have financial commitments.

BALPA (airline pilots union) and the Civil Aviation Authority must act now, publicly, to recognise the dangers to air crew and passengers caused by the effects of OPs being drawn into the aircraft, in particular the BAe146 and B757 (see Private Eye 7 July 2006 and a recent report by Channel 4).

We met with Lord Tyler recently to discuss these issues and he is to discuss them with colleagues in both houses.

OPIN is still answering frequent calls for support and information from OP sufferers, and still the Department of Health will not institute a programme of education on OPs for doctors.