BERLIN, Germany -- Industrialized as well as developing countries are under threat of asbestos exposure in the workplace, said researchers at the 11th Annual Congress of the European Respiratory Society today in Berlin. The scientists called the pulmonary effects of asbestos exposure a "time bomb in the lungs."
The European Respiratory Society (ERS) devoted one of its Monday symposia to the consequences of asbestos exposure. While the symposium's aim was to discuss in greater depth how to improve the management of workers who had suffered occupational exposure, participants also discussed the global problem caused by the mineral.
The symposium took on special meaning in the wake of the September 11 terrorist attacks in the United States. The collapse of the World Trade Center buildings has released measurable amounts of asbestos in the air in New York City, and some fear rescue workers and other emergency personnel may have suffered significant exposures.
In general, increasingly strict exposure standards have helped reduce the number of cases of asbestos related lung disease worldwide, as have bans on asbestos production and use in several countries.
But the scientists said there has been an alarming increase in asbestos related cancers, and that that trend is likely to continue for some time. This is partly because the effects of asbestos exposure can manifest themselves years or decades after the event - but also because millions of people, largely in poorer countries, continue to suffer daily exposure to asbestos.
RUSSIA, CHINA, CANADA TOP THE CHARTS
Global asbestos production was more than two million tons in 2000. The hands down winner was the Russian Federation, with 700,000 tons, said Antti Tossavainen of the Finnish Institute of Occupational Health in Helsinki, one of the symposium's speakers.
China came in second, with 450,000 tons, and Canada produced 335,000 tons - and exported almost all of it.
The data makes it clear that risks from asbestos are still very much present, and that developing countries may be looking at a bleak future. The respiratory specialists participating in the Berlin meeting emphasized that, in countries that have taken strong measures to reduce exposure, the full scope of the damage inflicted by asbestos became evident long after the exposure took place.
"We know that occupational asbestos exposure in Western Europe, North America, Japan and Australia was at its peak in the 1970s," said Tossavainen. "Now, recent estimates indicate that 30,000 new asbestos related cancers continue to be diagnosed there every year. They include some 10,000 mesotheliomas [cancers of the lung lining] and approximately 20,000 cases of lung cancer."
The introduction of increasingly strict limits for asbestos exposure has helped reduce the number of cases of diseases known as asbestosis, which are disabling lung lesions linked to very high asbestos exposure.
For example, Pascal Dumortier of the Erasmus Hospital in Brussels, Belgium, explained that asbestos imports into Belgium have fallen steadily since 1975, from some 85,000 tons to below 1,000 tons in 1999, and that maximum exposure standards have been tightened several times.
A very slight decrease over time in the average concentration of asbestos was seen in a review of thousands of samples of lung tissues taken from Belgian workers exposed to asbestos between 1983 and 2000.
However, "this reduction is lost entirely if the 27 most heavily exposed individuals are excluded from the calculation," Dumortier emphasized. "While epidemiological studies confirm that the risk of dying from asbestosis as such is now very low, at least in the countries that now have regulations ensuring only a very low exposure rate, we will continue to see new cases of mesotheliomas for years to come."
CANCER RATES TO RISE UNTIL 2020
For other asbestos linked diseases, particularly the cancers of the lung lining known as mesotheliomas, scientists do not know whether exposure over time plays an important role. According to the Berlin speakers, mesothelioma rates in industrialized countries seem to have dropped as they have cut back on the amount of asbestos used each year.
But overall, the risk of developing asbestos related cancers appears to increase over time.
Marc Letourneux of the University Medical Center Cte de Nacre in Caen, France, told the symposium that, "The epidemiological outlook is clear: there will be a steady rise in the frequency of asbestos linked cancers until at least 2010 or 2020 because they take years to manifest themselves."
"The mesothelioma rates are expected to rise in France by as much as 25 percent every three years, with some 150 fatalities every year between 2010 and 2020, almost twice the rate of 1996-1997," Letourneux warned.
The figures make it clear that any level of asbestos exposure can increase the risk of developing a cancer of the lungs, Letourneux added.
Another study, presented at the meeting by Krassimir Mitchev of the Erasmus Hospital in Brussels, found that almost one person in every seven in a randomly chosen urban population bore the scars of asbestos exposure.
HOW TO RESPOND?
"This is the crux of the question, and there are no uniform satisfactory answers at present," commented Paul De Vuyst, co-chair of the symposium and chair of the Occupational and Environmental Health Group in the ERS Occupation and Epidemiology Assembly.
The meeting participants discussed the benefits and drawbacks of systematic screening for the signs of past exposure in all patients who have had contact with asbestos. Pierre Alain Gevenois, co-chair of the symposium and president of the Imaging Group in the ERS Clinical Assembly, warned that annual or even semiannual scans may not catch cancers early enough to improve the chances of survival.
"During the period between two scans, it is perfectly possible for a bronchopulmonary cancer to appear, develop and evolve," Gevenois said.
As there is little hope of curing mesotheliomas once they are detected, the experts recommended focusing screening efforts on other lung cancers, for which an early diagnosis may improve chances of survival.
Dr. Gregory Wagner of the U.S. National Institute for Occupational Safety and Health presented a review of promising new American research into asbestos related lung cancers. The research provides some hope that survival rates may be improved through the use of periodic scans of smokers who have been exposed to asbestos.
The symposium's participants said it is now urgent - more than a century after the health threats of asbestos were first documented - to determine the best ways of dealing with this medical time bomb.
At the close of the symposium, De Vuyst called for the creation of a "European Task Force responsible for centralizing data and defining precisely what groups can benefit most from new types of early screening for serious and potentially curable pathologies."