Transcript COPD - Background in the US

COPD - Background in the US
• Chronic obstructive pulmonary disease
(COPD) includes chronic bronchitis,
emphysema, bronchiectasis, and chronic
airway obstruction.
• Estimated prevalence of 8.5% in the U.S.
• In 1999 COPD was the fourth leading
cause of death in US (> 124,000 deaths)
Occupational burden of COPD
• American Thoracic Society statement
(2003) estimated 15% of COPD is caused
by occupational exposures
• Specific agents studied to date:
– silica, coal dust
– grain dust, wood dust, cement dust
– cadmium, welding fumes
– possibly isocyanates
COPD in construction workers
• Glencross et al. [1997] found that sheet metal
workers followed over a 10-year period
sustained significantly accelerated loss of FEV1 if
they were exposed to asbestos and smoked.
• Using data from the NHANES III for 1988-1994,
workers in construction trades have been shown
to be at increased risk of COPD based on PFT
data [Hnizdo et al., 2002].
COPD in construction workers
• Oliver (2006) found that tunnel
construction workers exposed to respirable
crystalline silica and cement dust are at
increased risk for airway disease. Extent of
risk varied by trade and work activity.
Impact of total dust in construction
Bakke 2002 Appl Occ Env Hyg
• Longitudinal accelerated decline in lung function
• Exposure to dust and gases from diesel exhaust,
blasting, drilling and rock transport in tunnel
work enhances the risk for accelerated decline in
FEV1, respiratory symptoms, and COPD in
tunnel workers compared with other heavy
construction workers
Exposures to total dust in
construction
Bakke 2002 Appl Occ Env Hyg
Among construction workers performing tunneling
operations:
• shotcreting operators
6.8 mg/m3
• tunnel boring machine workers 6.2 mg/m3
• shaft drilling workers
6.1 mg/m3
• outdoor concrete workers
1.0 mg/m3
• electricians
1.4 mg/m3
• support workers
1.9 mg/m3
Exposure assessment in US construction
(Rappaport 2003)
Median values for respirable dust and silica
(mg/m3 )
– Painters 13.5 total / 1.28 silica
– Laborers 2.46 total / 0.350 silica
– Bricklayers 2.13 total / 3.20 silica
– Operating engineers total 0.720 / 0.075 silica
151 personal measurements were analyzed
from 80 workers on 36 construction sites
Questions
• Can we separate effects of different components
of construction dust?
• Is most of the COPD due to specific agents, such
as silica, diesel exhaust and welding fume? Or is
there a combined impact of other “nuisance”
dusts?
• Focus on epidemiology or controls?