I am a frequent flyer with my business taking me to different countries all year round. As such I am often subjected to being sprayed, along with my fellow passengers, with insecticide by the flight attendants as the airline in question strives to kill off any disease-causing bug that may have stowed away on embarkation. I have heard that these sprays may contain piperonylbutoxide to increase the potency (and toxicity) of the active chemicals. I am concerned about the accumulative and long term side effects of such substances for passengers and all flight crew. What are the risks? A.T.

DR RAOUL GOLDBERG REPLIES:I am pleased that you have raised this question regarding spraying insecticide in aircraft because it was an issue I took up myself some months ago. This was following a flight to London  in May last year when I was accompanying a cancer patient to a cancer clinic in the UK. We were sitting in a bulk head seat close to the front of the aircraft when the insecticide called SERVOPAK containing the active ingredient PERMETHRIN came wafting through the air space. For some reason the ventilation over our seats was not working properly and the passenger I was accompanying immediately began to react to the spray, with coughing, chest pain, wheezing and progressive bronchospasm. We had to call for oxygen, and it took the best part of an hour for her attack to subside. My eyes and throat were also irritated and we heard many other passengers behind us coughing for some 20 minutes after the insecticide had been sprayed.

Speaking to several flight attendants during the flight, we discovered how concerned they were at their continued exposure, one hostess saying how she was struggling with hay fever and sinusitis and was ready to come forth as a witness if we would take up the issue. I wrote to the airline in question asking for some information on the safety and toxicity of the products but received no response.

Permethrin as you probably know is a commonly used insecticide and insect repellent, belonging to a family of synthetic chemicals called pyrethroids which occur naturally in certain plants. It is highly toxic to insects, including bees, as well as aquatic organisms, fish and cats. It is claimed to have low toxicity for mammals and human beings, yet the US Environmental Protective Agency regards it as having carcinogenic effects, as it has been shown to induce liver tumours in rats and mice.

There can be no question that individuals with chemical sensitivities react adversely to permethrin and other insecticide sprays. I do not know whether there are other substances such as piperonylbutoxide in these sprays. But these reactions, together with the experiences of many passengers should be good enough reason for the relevant authorities to investigate the potential toxicity more thoroughly. Even though there are currently insufficient studies to ban its use outright, greater care and consideration for sensitive individuals should be taken wherever people come into close contact with any potential carcinogens. For instance protective masks should be given to sensitive individuals and optimal ventilation should be provided.

As a medical practitioner with a special interest in integrated cancer therapy, I feel that this issue of indiscriminate insecticide spraying in aircraft must be addressed as a public health priority.

I am grateful to you as a concerned citizen that you have raised this issue.