stf - audiência pública do amianto - 31/08/2012 - supremo tribunal federal

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Esta apresentação em PowerPoint é para o uso do Supremo Tribunal Federal do Brasil exclusivamente.

Esta apresentação em PowerPoint e os vídeos dentro não deve ser distribuído ou copiado para qualquer outro partido.

Uma impressão de PDF pode ser utilizado para a distribuição limitada.

This PowerPoint presentation is for the use of the Supreme Court of Brazil exclusively.

This PowerPoint presentation and the videos within should not be distributed or copied to any other party.

A PDF printout may be used for limited distribution.

David Bernstein © copyright 2012 1

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David M. Bernstein, Ph.D.

FEDERAL SUPREME COURT OF BRAZILSTF PUBLIC HEARING – ASBESTOS

31 August 2012


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Very frequently, amphibole asbestos (amosite, crocidolite) was mixed with the chrysotile.

There was little or no attempt to differentiate exposure to these two very different minerals.


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Chrysotile is a rolled sheet material like mica.

The sheet is about 8 angstroms (0.8 nanometers) thick and,

because of molecular constraints, is rolled into cylindrical form.

The cylinders are chrysotile fibrils which bunch together to form a chrysotile fiber.

The chrysotile fiber is acid soluble (Pundsack, 1955).

.David Bernstein © copyright 2012 7

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Chrysotile

8 angstroms (0.8 nanometers) 8 angstroms (0.8 nanometers)

Decomposes in acid


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In acid the rolled sheet of the chrysotile fiberbreaks apart into small pieces.

This is important:

In the lung – the cell which clears fibers & particles from the lung – the macrophage –creates an acid environment.

In the gut (acid environment) .


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The amphibole asbestos class of fibers are formed as solid rods/fibers (Skinner et al., 1988).

The structure of an amphibole makes it very strong and durable.

The external surface of the crystal structures of the amphiboles is quartz‐like, and has the chemical resistance of quartz.

Amphibole fibers, therefore, have negligible solubility at any pH that might be encountered in an organism (Speil and Leineweber, 1969).


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Not soluble in acid or neutral pH


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Fiber dimensions (length and diameter)

Fiber biosolublity (durability)

Fiber dose


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pH 7.4pH 7.4

pH 4pH 4

Macrophage

pH 7.4

pH 4

Macrophage


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pH 7.4pH 7.4

pH 4pH 4

pH 7.4

pH 4


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The more recent toxicology studies demonstrate that:

Brazilian chrysotile asbestos has a relatively short biopersistence and

does not result in pathological response even in a sub‐chronic inhalation toxicology study at an exposure concentration 5,000 times greater than the US Threshold Limit Value of 0.1 f(WHO)/cm3.


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Following such exposures, chrysotile asbestos produces neither

a pathological response in the lung

nor in the pleural cavity.

In addition, the chrysotile fibers clear rapidly from the lung and

are not observed at the visceral pleural surface, in the pleura nor on the parietal pleural surface.


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In the lung, immediately following a 5 day exposure, the amphibole fibers have been shown to produce extensive inflammation with pathological lesions.

Within 28 days after the 5 day exposure, interstitial fibrosiswas observed in the lung.

The amphibole fibers are poorly cleared from the lung with the longervfibers longer persisting through the life‐time of the rats.


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Within 2 weeks after the 5 day exposure, amphibole fibers were:

observed penetrating through the visceral pleural surface and

were associated with extensive inflammation and fibrotic development in the pleura.

These pathological changes parallel closely those in humans who develop mesothelioma.


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The early case‐control studies of mesothelioma provided relationships of occupational exposure to asbestos.

However, due to the state of occupational hygiene measurements at the time, none of the studies were able to use exposure measurements which included asbestos specific fiber number or fiber type.

That is, the attribution of fiber specific effect was performed based upon hypothetical exposures rather than real data.


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The associations to disease were attributed to the fiber most used without consideration of the toxicological criteria that have been understood more recently to determine fiber potency:

fiber composition,

biopersistence and

fiber length.

The inhalation toxicology studies have shown that even a small exposure to long fiber amphibole asbestos is pathogenic.


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The authors of very few of the epidemiology studies on asbestos were able to state that there was no amphibole exposure present in the cohort.

One of the most comprehensive reviews of these studies by Hodgson and Darnton (2000) considered as “chrysotile only”, studies actually characterized as predominately chrysotile exposure,

and stated that small quantities of amphibole fiber were ignored as being important to the findings in some cohorts.


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Some of the factors not considered by the authors:

• Proximity to other industrial sources including a major amphibole asbestos source.

• Use of local death rates which were 3 times the national rates used by Dement.

• Occurrence of concurrent or prior exposures as indicated by the obituaries.

• Use of national smoking rates.David Bernstein © copyright 2012 27

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Weill et al. (1979): “No excess mortality was observed following exposure for 20 years to chrysotile asbestos at exposure levels equal to or less than 100 MPPCF.years (corresponding to approximately 15 fibers/cm3 x years)”.

Thomas et al. (1982) "Thus the general results of this mortality survey suggest that the population of the chrysotile asbestos‐cement factory studied are not at any excess risk in terms of total mortality, all cancer mortality, cancers of the lung and bronchus, or gastrointestinal cancers".


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Gardner MJ et al. (1986) : No excess of lung cancers or other asbestos‐related excess death was reported, at mean fiber concentrations below 1 fiber/cm3, although higher levels had probably occurred in certain areas of the asbestos‐cement factory.

Ohlson & Hogstedt (1985) : No excess work related mortality was observed at cumulative exposures estimated at about 10‐20 fibers/cm3.years.


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Carel et al. (2006): study led by the International Agency for Research on Cancer (IARC),

The OR for asbestos exposure was 0.92 (95% confidence interval (CI) 0.73‐1.15) in Central and Eastern Europe

No effect

Schneider et al. (2010): reported that the fibrosis scores of the asbestosis cases correlated best with the number of uncoated commercial amphibole fibers.


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DAVID

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The 3 main areas evaluated for each fiber type were:

Epidemiology Toxicology Biopersistence


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37

The Report of the World Health Organization workshop on chrysotile asbestos substitutes, has clearly reported that there is very little scientific basis for the evaluation of the proposed substitutes for chrysotile.

For many of the fiber types, the limited data available would suggest that they should be of considerably greater concern than chrysotile.

David Bernstein © copyright 2012

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The scientific evidence recently published, as shown by cohorts studies;

epidemiological reviews and

inhalation toxicology studies,

provides strong support that chrysotile is significantly less hazardous than the amphibole forms of asbestos (e.g. crocidolite and amosite).


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The toxicology studies clearly demonstrate the importance even of short term exposures to amphibole asbestos in the causation of disease.

In the earlier epidemiology studies, there was little means available to quantify whether the workers were exposed to amphibole asbestos.


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The Report of the World Health Organization workshop on chrysotile asbestos substitutes, has clearly reported that there is very little scientific basis for the evaluation of the proposed substitutes for chrysotile.

For many of the fiber types, the limited data available would suggest that they should be of considerably greater concern than chrysotile.


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With proper control and use, chrysotile asbestos in its modern day high‐density cement applications does not present an excess risk of either:

lung cancer or

mesothelioma

of any significance to public and/or worker health.


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I would be pleased to provide copies of all supporting scientific publications to the Supreme Court.


stf - audiência pública do amianto - 31/08/2012 - supremo tribunal federal

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