Medical aspects of asbestos exposure

Sjaak Burgers

respiratory physician

Netherlands Cancer Institute, Amsterdam

s.burgers@nki.nl

Medical consequences

• mesothelioma

• asbestosis

• lung cancer

• benign pleural plaques

Today

• Medical introduction

• Asbestos – mesothelioma– lung cancer

• (Problems in) risk assessment

Mesothelioma captures the lung

Mesothelioma captures your breath

Mesothelioma: local growth

Mesothelioma: high mortality

Cisplatin vs cisplatin-pemetrexed. Vogelzang, JCO 2003

survival with the BEST availabletreatment

Lung cancer

• 15% cure rate

• 50% 1-year mortality

• 90% smoking-related

• asbestos – increases the risk for lung cancer– more than adds to the smoking-induced risk

40-y old women.Lung cancer recently

diagnosed.

Risk assessment

• Whatever the risk is,

• the consequences are life threatening.

Difference between exposure to

• asbestos

and

• sigarette smoke

Mesothelioma mortality in North American insulation workers is independent of age

0

10

20

10 25 35 45 55

Years since beginning exposure

Cu

mu

lativ

e m

eso

the

liom

a r

isk

(%)

Age at first exposure (years)

---- 15-24 ---- 25-34 ---- 35+

Peto et al 1982: Br J Cancer 45: 124-135

Lung cancer mortality is almost constant in ex-smokers

0

1

2

3

4

5

6

7

40 45 50 55 60 65 70 75

Age

Dea

th ra

te p

er 1

000 Age stopped

60-64

55-59

50-54

40-49

Halpern et al 1993: JNCI 85, 457

Evidence

• individual data– “All my colleagues died of this disease”.

• local data

• national data

• global data

Environmental exposure: Cape blue asbestos

• 33 cases• median age 49y (31-

68y)• exposed to asbestos

no other cases in South Africa

Wagner et al Br J Industr Med 1960

Environmental exposure:Dutch example

mesothelioma incidence in the Netherlands, females

Environmental exposure

• roads paved by Eternit remnants

• mean exposure 0,11 fiber years

• expected 4 cases, observed 26 cases

2 national examples

DeathsExposure index

1940 1960 1980 2000 2020 2040

0

500

1000

1500

2000

Mes

othe

liom

a de

aths

0

50

100

150

200

Exp

osur

e in

dex

Fitted/projected deathsObserved deaths

Exposure index(fitted/projected)

Projected British male mesothelioma deaths Hodgson et al (2005) Br J Cancer 92: 587

0

1

2

3

4

5

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

aan

tal/

nu

mb

er

per

100

00

0 (

ES

R)

jaar van overlijden/ year of death

Trend in kankersterfte in Nederlandtrend in cancer mortality in the Netherlands

mannen/ males vrouwen/ females totaal/ both sexes

Pleura (1961-1995) / mesothelioom (vanaf 1996)pleura (1961-1995) / mesothelioma (as of 1996)

bron/ source: CBS

Banning asbestos helps

1993

1982

1977

Global data:asbestos consumption /meso deaths

Nawrot, Lancet 2007 Lin, Lancet 2007

Translation to risk assessment

• still no answer to the question

• “What is the risk that a particular person gets cancer due to a particular asbestos exposure?”

Complicated exposure-response relation for

mesothelioma

• I=incidence; t= time since exposure; f=fiber count; d=duration of exposure; KM= fiber dependent

EPA, 1986

Is there a safe exposure level?

fibres/m3

(fibres/ml)Occupational exposure level corresponding to the risk levelchrysotile upto 20% amphib amphibole

4.10-3 200,000 (0.2)

130,000 (0.13)

42,000 (0.042)

4.10-5 2,000 (0.002)

1,300 (0.0013)

420 (0.00042)

current Dutch safety level 0.02 fibres/ml = 1/10 of EU standard

Risk level: likelyhood of dying of cancer as a result of exposure

Theoretically there is; Netherlands Health Counsil:

Thus,

• abundant evidence relating asbestos to mesothelioma and lung cancer

• exact risk levels hard to calculate