Asthma in Heavy and Highway Construction Workers
Exposed To Silica |
|
Christine Oliver, MD, MS
Acknowledgments
We gratefully acknowledge the support and assistance of the leaders
and members of the participating local unions, of the General Agent
of the Boston Building and Construction Trades Council Joseph Nigro,
of the New England Regional Office of the Occupational Safety and
Health Administration, and of the New England Laborers' Health and
Safety Fund - in particular, Drs. Thomas Hicks and Noell Woolley.
CAT |
Central
Artery/Tunnel construction project |
CI |
Confidence
interval |
HDPE |
High-density
polyethylene |
OR |
Odds
ratio |
OSHA |
U.S.
Occupational Safety and Health Administration |
PEL |
Permissible
exposure limit |
SCA |
Symptoms consistent with asthma |
Methods
Workers' respiratory and smoking histories
Work histories
Construction techniques
Statistical analysis
Results
Respiratory symptoms and physician-diagnosed asthma
Discussion
Conclusions
References
Tables
In December, 2000 the federal Occupational Safety and Health Administration
(OSHA) carried out a safety and health inspection on a contract site
(CO9A4) on Boston's Central Artery/Tunnel (CAT) highway construction
project. The inspection was conducted under a National Emphasis Program
for silica and a Local Emphasis Program for the CAT. Work on the site
involved construction of (1) two tunnels linking Boston's underground
central artery to the Massachusetts Turnpike (I-90 West and I-90 East)
and (2) an exit ramp connecting I-90 westbound to the central artery.
On November 1, 2, and 3, 2001, a health survey of more than 300 construction
workers from the CO9A4 site was carried out by Occupational Health
Initiatives and the New England Laborers Health & Safety Fund. The
survey was done under the auspices of the Building & Construction
Trades Council of the Metropolitan District and local unions representing
the trades on the site. The focus of the survey was silica. No definite
cases of silicosis were identified. However, review of the questionnaires
completed by survey participants revealed what appeared to be a high
number of positive responses to questions about wheeze and attacks
of wheeze associated with shortness of breath. In some, but not all,
cases there was a prior history of physician-diagnosed asthma. Only
a few reported taking medication for asthma. These findings suggested
a higher-than-expected prevalence of asthma (compared with the general
population) among construction workers on the site, undiagnosed and
untreated for the most part.
Based upon these findings, three hypotheses were generated:
- There is an increased prevalence of asthma defined on the basis
of physician diagnosis or symptoms among these heavy and highway
construction workers.
- For many of these workers, asthma is undiagnosed.
- For many of those with physician-diagnosed asthma, control
is not adequate.
The present study tests these hypotheses by statistical analysis of
the data collected at the time of the survey, and examination and
assessment of the results
All construction workers who had worked on the construction site during
the time period June 1999 through December 2000 were invited to participate
in a health survey held in November 2001 at the hall of Plumbers Union
Local 12 in Boston, Mass. Trades included laborers, carpenters (including
pile drivers), ironworkers, tunnel workers, operating engineers, and
electricians.
Workers' respiratory and smoking histories
Each worker's respiratory history was derived using the Epidemiology
Standardization Project questionnaire (Ferris 1978). The focus of
data analysis and the present report is asthma. Because the focus
of the survey was silicosis, standardized questions for asthma epidemiology
were not included on the questionnaire (see Venables and others 1993).
Also analyzed but not reported here were chronic bronchitis and shortness
of breath.
Based upon answers to questions about current symptoms of wheeze and
prior history of asthma, participants were classified as having symptoms
consistent with asthma (SCA) or physician-diagnosed asthma. A
point system was developed to define SCA. Each of the following symptoms
was given one point: wheeze with cold, wheeze occasionally apart from
colds, wheeze most days or nights, two or more attacks of wheezing
associated with shortness of breath. If a participant reported one
or more attacks of wheeze associated with shortness of breath, one
point was given also for a positive response to the question, "Have
you ever required medicine or treatment for the(se) attack(s)?" Participants
who received 3 or more of these 5 possible points were classified
as SCA.
Physician-diagnosed asthma was determined on the basis of a
"yes" response to the question, "Have you ever had asthma?" and "yes"
to the question, "Was it confirmed by a doctor?" With a "yes" answer
to the question, "Do you still have it?," a participant was included
in a subcategory of current physician-diagnosed asthma. Both subcategories
of physician-diagnosed asthma (those who don't and do still have it)
were analyzed with regard to self-reported symptoms of asthma.
Participants were classified as current smokers if they reported
"ever smoking cigarettes" and that they "now smoke cigarettes" (as
of one month before the survey). Former smokers were those who reported
"ever smoked" and "not smoking now." Never smokers were those who
reported "no" to ever smoking cigarettes. Pack-years of cigarettes
were calculated (for ever smokers) by multiplying total number
of years of smoking by average number cigarettes per day over the
entire time that they smoked, and dividing by 20 (number of cigarettes
in a pack).
Work histories
Principal work activities on the construction site studied were related
to the construction of the two tunnels and the exit ramp.
The work history obtained from each questionnaire included present
occupation/trade, union and local union number, usual occupation/job,
years of work at usual occupation, and months of work on the CAT contract
site of interest. Because of small numbers, pile drivers were grouped
with carpenters; similarly, plumbers, millwrights, and nonunion engineers
and managers were grouped with "other" for purposes of data analysis
(with a group as small as "other," statistical results must be interpreted
with caution). Included in the questionnaire were questions about
work at three specific activities on the site: tunneling/mining, breaking
through slurry walls, and chipping or hammering caisson overpour.
The activities were selected because personal and area sampling on
the site by OSHA and the responsible contractor showed elevated silica
levels during each of these activities (silica is found in quartz,
other rock, sand and masonry). This study assumed that total dust
exposures would be high where silica levels were high, and thus included
these three activities in the analyses. (Unlike tunneling and slurry
wall breakthrough, most of the chipping or hammering of caisson overpour
was done above ground.)
Months of work on the site was determined on the basis of start
and stop dates and self-reported total months on the job. For those
who had missing information for stop date and who did not report total
number of months on the site, it was assumed they were still working
on the site and the survey date was used to calculate total number
of months. Years at usual job was determined on the basis of
the response to the question, "Number of years employed in this occupation."
Construction techniques
In order to better assess the results described below, additional
information was sought about the construction work performed on this
site. Sources of information included the CAT web site and consultation
with OSHA personnel, trades working on the site, and the engineer
responsible for a ground-freezing operation.
Use of jacking boxes. The construction of the tunnels
involved the use of "jacking boxes." A temporary concrete jacking
box was built inside each of three concrete jacking pits dug along
the path of I-90. The top of each pit was open. Each box was 80 feet
wide and 40 feet high, with an open front end and two levels of four
compartments each. Operators of heavy equipment and tunneling workers
worked from inside the compartment at the open end of each box. The
boxes were moved using cables that were along the bottom of each pit.
At the front of each pit was a concrete slurry wall; beyond the slurry
wall, the ground had been frozen (see below). Equipment was used to
break through the slurry wall to create a tunnel through the earth.
Ground freezing. Because the I-90 tunnel had to pass
under a busy rail terminal, the soil had to be stabilized to avoid
settling of the rail lines that were overhead. This was accomplished
by ground freezing: A system of pipes was installed in the ground.
The piping system was a series of four 4-inch-diameter carbon steel
pipes with closed ends into which were dropped 1½ inch high-density
polyethylene (HDPE) pipes with open ends. Brine was chilled to -23
degrees Centigrade in a refrigeration plant on site and circulated
between the carbon steel and HDPE piping. Over time, the brine cooled
the soil and eventually froze the ground outward from the pipes.
Breaking through the slurry wall. The first step in
actual tunnel construction was breaking through the concrete slurry
wall at the head of the jacking pit. Operating engineers used a roadheader
- with a rotary blade - to break through slurry wall and bore through
the frozen ground behind it; a large bucket and crane removed and
lifted soil to the surface. Any granite or rocks encountered in the
soil were broken up by hoe rams. The roadheader and jacking equipment
were electric; other heavy equipment, including forklifts, cranes,
CAT loader, manlift, and bobcat were diesel powered. The jacked sections
were 150 feet long for the ramp tunnel, 260 feet long for the I-90
westbound tunnel, and 560 feet long for the I-90 eastbound tunnel.
Burning pipes. In order for a jacking box to be jacked forward,
the pipes used for ground freezing had to be removed (the ground was
still frozen). The removal was accomplished by burning the carbon
steel pipes with a manganese rod using compressed oxygen at 5,000
degrees Fahrenheit. According to the engineer overseeing the ground-
freezing operation, the brine and HDPE pipes were pulled out before
the steel pipes were burned-in about 90% of the time; the rest were
left in place.
Statistical analysis
In the data analysis, logistic regression was used to model the relationship
between dichotomous (yes, no) outcomes and work exposures. Principal
outcomes of interest were SCA and physician-diagnosed asthma. To assess
the relationships of outcomes to exposure variables while controlling
for the possible confounding effects of the covariates, adjusted odds
ratios (ORs) were calculated from models that included exposure variables
and other covariates such as age, gender, and smoking. The unadjusted
models were fit separately for each covariate. The number of observations
in these models varied by the amount of missing data for the independent
and the dependent (outcome) variables. The adjusted model includes
only participants with complete data on all covariates. In computing
odds ratios, laborers were chosen as the reference group because of
the relatively low prevalence of asthma in that group. Electricians
had a lower prevalence, but the total number of electricians was small
(21 compared to 89 laborers).
The analysis assumed an alpha of 0.05 and calculated 95 percent confidence
intervals (CIs). An overall p-value was also presented to allow an
assessment of the importance of each covariate to the strength of
the model, or of its predictive capability. For instance, in some
cases, the 95% CI shows significant (meaning the CI does not include
1) differences between groups. However, the p-value may not be significant
(<0.05), indicating that the covariate may not be a strong predictor
of the outcome.
A total of 343 workers completed questionnaires, but data analysis
was performed for 317 participants. The final count excluded 26 participants
who reported working 30 days or less on the site or who had missing
information on length of time worked on the site.
The average age for the whole group of 317 was 41 years (table
1). Most were male and Caucasian. About 29% were currently smoking.
Work histories showed a high correlation between present occupation/trade
and usual job/occupation. More than half of the participants were
laborers or carpenters (table 2). Participants had
been employed in their usual jobs for 14 years, on average, and had
been working on the site an average of about 22 months. Of the group
as a whole, 36% reported having done tunneling/mining, 45% breaking
through slurry wall, and 51% chipping or hammering caisson overpour
while on the project.
Respiratory symptoms and physician-diagnosed asthma
The number of workers who reported physician-diagnosed asthma was
far less than the number showing symptoms consistent with asthma (table
3). Prevalence of physician-diagnosed asthma and SCA varied by
trade (table 4). Higher prevalence of physician-diagnosed
asthma was observed among operating engineers, laborers, and carpenters
at about 10%, 8%, and 7%, respectively. Carpenters, tunnel workers,
and operating engineers were more likely to report SCA: about 35%,
34%, and 32%, respectively.
In the logistic regression analysis, physician diagnosis of asthma,
breaking through slurry walls, and number of months on the site were
all significantly associated with SCA (table 5).
Those with physician-diagnosed asthma were ten times more likely to
report SCA as those without physician-diagnosed asthma. With regard
to workplace activities, those who reported breaking through slurry
walls were three times more likely to report SCA, compared with workers
who didn't break through the walls. The breaking through was done
primarily by operating engineers and tunnel workers, but carpenters
were exposed as bystanders.
However, participants who worked 18 or more months on the site were
one-fourth as likely to report SCA as those who worked less than 10
months. This finding is consistent with an earlier study of construction
workers on the CAT project and suggests that workers who have respiratory
symptoms tend to leave the construction project earlier than they
would have otherwise (Oliver and others 2001).
Smoking status was a statistically significant predictor of SCA when
other relevant factors were taken into account. Current smokers were
more than twice as likely to report SCA, compared with former or never
smokers. Present trade was not a significant predictor of SCA. However,
there were some significant within-variable differences. All trades
were more likely than laborers to report SCA; but for carpenters,
the difference was significant at a greater than fourfold increase.
The statistical findings support hypotheses generated by responses
to questions about wheeze and physician diagnosis of asthma at the
time of this survey of silica-exposed workers involved in tunnel operations
on the CAT construction project. The construction process was somewhat
unusual in its use of jacking boxes and ground freezing.
In the present study, 6.6% of participants overall reported physician-diagnosed
asthma. By comparison, data collected in Massachusetts in the 2000
Behavioral Risk Factor Surveillance System survey showed that 11.9%
of 8,139 respondents answered "yes" to the question, "Have you ever
been told by a doctor that you have asthma?" (MMWR 2001) This finding
suggests that asthma is under-diagnosed in those who participated
in this survey. Further, of the 21 in this survey in whom asthma was
diagnosed, more than half reported SCA.
In contrast to the prevalence of physician-diagnosed asthma, about
25% of participants reported symptoms consistent with asthma, with
a range of 19% in laborers and electricians to more than 30% in carpenters,
tunnel workers, and operating engineers. About 23% of ironworkers
reported SCA.
Slurry wall breakthrough emerged as a significant risk factor for
SCA in the analysis, depending on trade. Participation in this work
activity was associated with a sevenfold increase in risk for SCA
in carpenters, an increase in risk that was statistically significant
(OR 6.87, 95% CI 1.66-28.39).
Silica levels measured during slurry wall breakthrough were high.
OSHA's recalculation of sampling data collected by the general contractor
during the breaking through of slurry walls revealed that of 11 samples
taken, six showed calculated silica levels of 130%, 135%, 200%, 220%,
305%, and 1170% of the OSHA permissible exposure limit (PEL). Area
samples taken during slurry wall breakthrough showed silica levels
314% and 397% of the PEL. These data are consistent with high dust
exposures during slurry wall breakthrough reported by workers on the
site and are an indicator of high-level exposure to cement dust, as
silica and cement dust are often fellow travelers. Silica has not
been reported to cause asthma. However, Portland cement present in
most cement manufactured in the United States has been reported to
cause asthma ( Alvear-Galindo and others 1999; DeRaeve and others
1998). Portland cement contains hexavalent chromium, a known irritant
and sensitizer to the airways and to the skin.
The tunneling operation involved other potential causes of asthma.
These included diesel emissions and fumes/vapors from the burning
of the steel and HDPE pipes. Diesel emissions are a known cause of
asthma, most likely because of irritants in the particulate and the
vapor phase (Rudell and others 1996; Wade and Newman 1993; Ulfvarson
and others 1991). The level of risk associated with burning HDPE is
unknown presently. Polyethylene itself has been reported to burn cleanly,
but if polyvinylchloride is an additive - as in the case of HDPE -
hydrochloric acid vapors may be generated (Sakata, Uddin, Koizumi,
and Murata 1996). If this occurs, the risk for airway inflammation
and asthma is high.
Carpenters were found to be at significantly increased risk for SCA
compared to laborers. The carpenters were downwind of the jacking
box during slurry wall breakthrough and followed along behind the
jacking box as the tunnel was bored. These findings suggest bystander
exposures that created an increase in risk for carpenters that was
greater than for trades directly associated with the slurry wall breakthrough
and the tunneling. Other as-yet-unidentified factors may be operative
as well.
With regard to these exposures, it is important to remember that they
occurred in relatively enclosed spaces. This was true for those working
in the jacking box, such as operating engineers and tunnel workers,
and for those working in the larger jacking pit, such as carpenters.
The present study reveals that over 25% of a group of heavy and highway
construction workers report symptoms consistent with asthma. Risk
was related to type of work and trade. The prevalence of physician-diagnosed
asthma was lower than that for the general adult population of Massachusetts,
which suggests that asthma in these workers is going undetected. That
10 of 21 of the workers in this survey with physician-diagnosed asthma
still report symptoms consistent with asthma suggests, as well, that
asthma is not adequately treated.
The findings are consistent with the results of a previously reported
study of airways disease in heavy and highway construction workers
and point out the need for better understanding of causes of asthma
in the construction industry. In addition, construction workers should
be better educated with regard to signs and symptoms of asthma (Oliver
and others 2001). Methods of reducing potentially harmful airborne
exposures in the construction industry exist (Rappaport, Goldberg,
Susi, and Herrick 2003). The methods, which include the use of water
to suppress dust during drilling and cutting, should be used.
Alvear-Galindo, MG, I Mendez-Ramirez , JA Villegas-Rodriquez, RC Chapela-Mendoza,
CA Eslava-Campos, and AC Laurell. 1999. Risk indicator of dust exposure
and health effects in cement plant workers. Journal of Occupational
and Environmental Medicine, 41:654-61.
DeRaeve H, C Vandecasteele, M Demedts, and B Nemery. 1998. Dermal
and respiratory sensitization to chromate in a cement floorer. American
Journal of Industrial Medicine, 34:169-76.
Ferris, BG. 1978. Epidemiology standardization project. American
Review of Respiratory Disease, 129:17-22.
MMWR, Morbidity and Mortality Weekly Report. 2001. Self-reported
asthma prevalence among adults-United States, 2000. 50(32) :681-86,
August.
Oliver, LC, H Miracle-McMahill, AB Littman, JM Oakes, and RR Gaita.
2001. Respiratory symptoms and lung function in workers in heavy and
highway construction: a cross-sectional study. American Journal
of Industrial Medicine, 40:73-86.
Rappaport, SM, M Goldberg, P Susi, and RF Herrick. 2003. Excessive
exposure to silica in the US construction industry. Annals of Occupational
Hygiene, 47(2): 111-22.
Rudell, B, M-C Ledin, U Hammarstrom, N Stjeernberg, B Lundback, and
T Sandstrom. 1996. Effects on symptoms and lung function in humans
experimentally exposed to diesel exhaust. Occupational and Environmental
Medicine, 53:658-62.
Sakata, Y, MA Uddin, K Koizumi, and K Murata. 1996. Thermal degradation
of polyethylene mixed with poly(vinyl)chloride and poly(ethyleneterephthalate).
In: Polymer Degradation and Stability. Northern Ireland: Elsevier
Science Ltd, pp. 111-17.
Ulfvarson, U, D Techn , R Alexandersson, M Dahlqvist, U Ekholm, and
B Bergstrom. 1991. Pulmonary function in workers exposed to diesel
exhausts: the effect of control measures. American Journal of Industrial
Medicine, 19:283-89.
Venables, KM, N Farrer, L Sharp, BJ Graneek, and AJ Newman Taylor.
1993. Respiratory symptoms questionnaire for asthma epidemiology:
validity and reproducibility. Thorax, 48:214-19.
Wade, JF, and LS Newman S. 1993. Diesel asthma. Reactive airways disease
following overexposure to locomotive exhaust. Journal of Occupational
Medicine, 35:149-54.
Table 1. Demographics: participants' age, gender,
race, and smoking status
|
Number
|
%
|
Age
(in years)
< 35
35-<40
40-<50
50+
Missing information
Mean (SD)=40.8 (9.6)
Range 19.9-66.8 |
91
71
94
57
4
|
28.5
22.5
29.8
18.0
1.3
|
Gender
Male
Female
Missing information |
309
7
1
|
97.5
2.2
0.3
|
Race
White
Black
Other
Missing Information
|
265
29
14
9
|
83.6
9.2
4.4
2.8
|
Smoking
Status
Current
Former
Never
Missing information |
93
63
157
4
|
29.3
19.9
49.5
1.3
|
Note: Total of 317 workers.
Table 2. Work history: participants' time spent
at job, site, and selected tasks, by occupation
|
Number
|
%
|
Present
occupation/trade/union Laborer
Carpenter
Electrician
Ironworker
Operating engineer
Tunnel worker
Other |
89
84
21
47
32
40
4
|
28.1
26.5
6.6
14.8
10.1
12.6
1.3
|
Number
of years at usual job
<=5
>5-15
>15-20
>20
Missing information
Mean (SD)=14.0 (9.4)
Range=1 to 46 |
75
114
57
59
12
|
23.7
36.0
18.0
18.7
3.8
|
Number
of months on C09A4 site
<=10
> 10-18
> 18-32
> 32
Mean (SD)=21.8 (15.0)
Range=1.5 to 77
|
88
73
80
76
|
27.8
23.0
25.2
24.0
|
Tunneled/mined
Yes
No
Missing information |
114
188
15
|
36.0
59.3
4.7
|
Broke
through slurry walls
Yes
No
Missing information |
143
158
16
|
45.1
49.8
5.1
|
Chipped/hammered
caisson overpour
Yes
No
Missing information |
163
139
15
|
51.4
43.9
4.7
|
Note: Total of 317 workers.
Table 3. Relationship of physician-diagnosed asthma
and symptoms consistent with asthma
Workers
reporting physician-diagnosed asthma |
Workers
showing symptoms consistent with asthma |
Yes
|
No
|
Missing
Information
|
Total
|
Yes-current |
8
(80.0%) |
2
(20.0%) |
0
(0.0%) |
10
(100.0%) |
Yes-not
current |
5
(45.5%) |
5
(45.5%) |
1
(9.1%) |
11
(100.0%) |
No |
67
(23.3%) |
206
(71.8%) |
14
(4.9%) |
287
(100.0%) |
Missing |
1
(11.1%) |
3
(33.3%) |
5
(55.6%) |
9
(100.0%) |
Total |
81 |
216 |
20 |
317 |
Note: "Physician-diagnosed asthma" includes a diagnosis at
any time, not just during the project.
Table
4. Description of workers by present occupation, selected occupations
|
Present
occupation/trade/union
|
P-value
|
Laborers
|
Carpenters
|
Electricians
|
Ironworkers
|
Operating
engineers
|
Tunnel
workers
|
Demographics
|
Average
(SD) age, in years |
40.8
(10.2)
|
41.4
(9.1)
|
38.1
(8.6)
|
38.9
(8.6)
|
45.2
(11.6)
|
39.4
(8.0)
|
0.0682
|
Smoking
status
Never % Current % Former % |
44.2%
38.4% 17.4%
|
59.0%
27.7% 13.3%
|
66.7%
0.0%
33.3%
|
57.5%
27.7% 16.7%
|
28.1%
25.0% 46.9%
|
46.2%
38.5% 15.4%
|
0
|
Average
pack-years of cigarettes (SD) among ever smokers |
17.3
(14.8)
|
15.1
(12.6)
|
9.4
(9.7)
|
21.1
(14.3)
|
17.2
(22.4)
|
17.5
(14.6)
|
0.6647
|
Work
History
|
Average
# of months at site (SD) |
22.9
(15.4)
|
21.5
(13.4)
|
15.7
(19.9)
|
21.3
(14.5)
|
22.9
(16.2)
|
22.4
(13.0)
|
0.0901
|
Average
# of years at usual job (SD) |
13.6
(9.7)
|
14.1
(7.7)
|
13.5
(9.7)
|
14.8
(9.2)
|
20.1
(12.8)
|
8.6
(5.4)
|
<0.0001
|
%
Broke through slurry walls |
59.8%
|
31.7%
|
20.0%
|
15.6%
|
78.1%
|
82.1%
|
<
.0001
|
%
Tunneled/mined |
20.0%
|
26.3%
|
28.6%
|
21.7%
|
93.8%
|
79.5%
|
<0.0001
|
%
Chipped caisson overpour |
82.4%
|
41.8%
|
31.6%
|
13.3%
|
73.3%
|
65.0%
|
<0.0001
|
Respiratory
outcomes
|
%
Physician-diagnosed asthma |
8.2%
|
7.1%
|
0.0%
|
2.1%
|
9.7%
|
5.6%
|
0.0757
|
%
Symptoms consistent with asthma |
19.0%
|
34.6%
|
19.1%
|
23.4%
|
32.3%
|
34.2%
|
0.2945
|
Note: SD
= standard deviation. P-values for categorical covariates are from
a chi-square test (for % physician diagnosed asthma, exact chi-square
test), and for continuous covariates from analysis of variance F-tests.
Physician-diagnosed covers worker's history, not just during the project.
Some participants - managers and trades included in "other" elsewhere
in this report - are not included in this chart. Total of 89 laborers,
84 carpenters, 21 electricians, 47 ironworkers, 32 operating engineers,
and 40 tunnel workers.
Table
5. Logistic regression results for symptoms consistent with asthma
|
Unadjusted
|
Adjusted
(n=270)
|
Odds
ratio
|
95%
CI
|
P-value
|
Odds
ratio
|
95%
CI
|
P-value
|
Age
<= 35
35-40
40-50
50+ |
1.00
1.58
1.39
0.55
|
0.78,
3.20
0.71, 2.72
0.22, 1.35 |
0.07
|
1.00
1.45
1.25
0.84 |
0.61,
3.45
0.56, 2.80
0.28, 2.49
|
0.186
|
Smoking
status
Never
Current
Former |
1.00
1.63
0.96
|
0.91,
2.91
0.47, 1.94 |
0.209
|
1.00
2.41
0.91 |
1.18,
4.92 0.35, 2.32
|
0.035
|
Physician-diagnosed
asthma
Yes
No |
5.71
1.00
|
2.19,14.90 |
0
|
10.41
1.00 |
2.76, 39.31
|
0.001
|
Tunneled/mined
Yes
No |
1.85
1.00
|
1.09,
3.17 |
0.03
|
1.20
1.00 |
0.49,
2.96
|
0.692
|
Broke
through slurry walls
Yes
No |
2.13
1.00
|
1.25, 3.63 |
0
|
3.32
1.00 |
1.25, 8.84
|
0.016
|
Chipped
caisson overpour
Yes
No |
1.26
1.00
|
0.74, 2.13 |
0.392
|
0.80
1.00 |
0.33,
1.93
|
0.623
|
Present
trade
Laborer
Carpenter
Electrician
Ironworker
Operating
engineer
Tunnel
worker
Other |
1.00
2.25
1.00
1.29
2.03
2.22
1.42
|
1.09, 4.66 0.30, 3.42 0.52, 3.09 0.79, 5.20 0.93, 5.32 0.14,
14.65 |
0.258
|
1.00
4.55
2.42
3.13
2.28
3.03
0.64 |
1.67, 12.99 0.51, 11.48 0.89, 11.10 0.56, 9.33 0.87,
10.50 0.03, 13.51
|
0.103
|
Months
at site
<=10
>10-18
>18-32
>32 |
1.00
1.05
0.50
0.30
|
0.54,
2.03 0.24, 1.04 0.13, 0.68 |
0
|
1.00
0.62
0.25
0.21 |
0.27,
1.44 0.10, 0.61 0.08, 0.54
|
0.001
|
Note: Total
of 317 workers.
|
© 2003, CPWR – Center for Construction Research and Training. All rights reserved.
CPWR is a research, development, and training arm of the Building and Construction
Trades Dept., AFL-CIO: CPWR, Suite 1000, 8484 Georgia Ave., Silver Spring,
MD 20910. (Edward C. Sullivan is president of the Building and Construction
Trades Dept. and of CPWR and Joseph Maloney is secretary treasurer.) Production
of this study was supported by grant CCU317202 from the National Institute
for Occupational Safety and Health, NIOSH. The contents are solely the responsibility
of the authors and do not necessarily represent the official views of NIOSH.
This paper appears in the eLCOSH website with the permission of the author
and/or copyright holder and may not be reproduced without their consent.
eLCOSH is an information clearinghouse. eLCOSH and its sponsors are not
responsible for the accuracy of information provided on this web site, nor
for its use or misuse.
eLCOSH
| CDC | NIOSH
| Site Map | Search
| Links | Help
| Contact Us | Privacy Policy
|