Table IV. Mortality From Non-Malignant Respiratory Diseases Within Occupational Cohorts Exposed to styrene.
| Cohort and Reference | Industry | No. workers | Required tenure | Standardized mortality ratio (95%CI) | Findings | Strength of evidencea | |
|---|---|---|---|---|---|---|---|
|
| |||||||
| NMRD | COPD | ||||||
| A—Frentzel-Beyme et al. [1978] | Styrene and polystyrene manufacturing | 1,960 | >1month | 0.46b,c | 0.95d,e (0.05–4.70) | (i) Air sampling performed during 1975: range of styrene concentration in air, <0.01 ppm (limit of detection) to 46.92 ppm Thiess and Friedheim [1978]; (ii) SMR for asthma, 1.49d,e (95%CI, 0.07-735); (iii) SMR for pneumonopathy, 4.13d (95%CI, 0.21– 20.38) | + |
| B—Marsh et al. [2001] | Vitreous fiber manufacturing | 32,110 | ≥1 year | 0.91 (0.62–1.27), 0.69 (0.45–1.01), 0.53 (0.24–0.99)f,g | Not reported | Styrene exposure in 3 of 10 plants included in study; exposure levels not reported | NA |
| C—Ott et al. [1980] | Styrene-based product manufacturing | 2,904 | ≥1 year | 1.59d,h (0.81–2.83) | Not reported | Exposure varied by work role and location; TWAs ranged from 0 to <10 ppm, with excursions reported as high as 88 ppm | + |
| C—Bond et al. [1992] | Styrene-based product manufacturing | 0.55 (0.37–0.79) | 0.85i (0.39–1.61) | RR for NMRD for styrene exposed workers compared with unexposed Michigan manufacturers, 0.75 (95%CI, 0.52–1.08) | NA | ||
| D—Bond et al. [1985] | Chemical manufacturing | 19,608 | ≥1 year | 0.95 (0.82–1.09) | 1.03i (0.78–1.34) | Workers hired 1965–1980 (younger workforce): (i) NMRD, SMR, 1.05 (95%CI, 0.90–1.22); (ii) emphysema, SMR, 1.06 (95%CI, 0.79–1.39); longer duration of employment associated with decreased rate of death from NMRD, P < 0.001 | + |
| D—Olsen et al. [1994] | Chemical manufacturing | 27,040 | 0.97j (0.88–1.08) | 1.19i,j (0.95–1.46) | SMRs among male workers ≥15 years since hire: (i) NMRD, 1.04 (95%CI, 0.94–1.15); (ii) emphysema, 1.26 (95%CI, 1.01–1.55) | ++ | |
| D—Burns and Carson [2003] | Chemical manufacturing | 27,795 | Males, 0.95 (0.87–1.03); females, 0.55 (0.35–0.82) | Not reported | SMR (95%CI) for NMRD by duration of employment: (i) 1–4 years, 1.15 (1.02–1.29); (ii) ≥15 years, SMR, 0.65 (0.56–0.76) | ++ | |
| E—Nicholson et al. [1978] | Styrene and polystyrene manufacturing | 560 | ≥ 5 years | 0.15d (0.0075–0.74) | Not reported | SMRs (95%CI) for NMRD by exposure: (i) high-exposure, 0 deaths; (ii) possibly high-exposure, 0 deaths; low-exposure, 0.67 (0.034–3.31)d | NA |
| F—Meinhardt et al. [1982] | Synthetic rubber manufacturing | 2,756 | ≥6 months | 0.49 (0.23–0.93) | Not reported | (i) Mean estimated TWA: (a) plant A, 0.94 ppm (range: 0.03–6.46 ppm); (b) plant B, 1.99 ppm (range: 0.05–12.3 ppm); (ii) SMR for NMRD: (a) plant A, 0.49 (95%CI, 0.28–1.13); (b) plant B, 0.97, (95%CI, 0.36–2.16) | NA |
| G—Matanoski and Schwartz [1987] | Synthetic rubber manufacturing | 13,920 | ≥1 year | 0.64c | Not reported | Mean estimated 8-hr TWA, 1.3 ppm (all workers) and 0.9–9.4 ppm (different job groups) Macaluso et al. [2004] | NA |
| G—Matanoski, et al. [1990] | Synthetic rubber manufacturing | 12,110 | 0.69 (0.58–0.83) | Not reported | SMRs (95%CI) by worker race: (i) white, 0.68 (0.56–0.82); (ii) black, 0.79 (0.47–1.24) | NA | |
| G—Sathiakumar et al. [1998] | Synthetic rubber manufacturing | 15,649 | 0.71 (0.62–0.81) | Not reported | (i) Ever hourly: SMR, 0.72 (P < 0.05); (ii) never hourly, SMR, 0.61c (P < 0.05); (iii) ≥10 years worked and ≥20 years since hire, SMR, 0.87 (95%CI, 0.71–1.06) | NA | |
| G—Sathiakumar and Delzell [2009] | Synthetic rubber manufacturing | 4,863 | ≥1 day | 0.97 (0.79–1.18) | Not reported | Only females included in study | NA |
| H—Welp et al. [1996] | Reinforced plastics manufacturing | 35,443 | ≥1 day | 0.81 (0.67–0.96) | 0.86h (0.66–1.10) | (i) Mean exposures, ∼200 ppm (early 1960s), 20–40 ppm (late 1980s); (ii) relative risk (RR) (95%CI) for NMRD by average exposure (ppm) using internal comparisons: <20, 1.00 (ref); 20–59, 0.37 (0.16–0.83); 60–119, 0.55 (0.26–1.17); 120–199, 0.67 (0.31–1.47); >200, 0.86 (0.38–1.93), P for trend = 0.08 | NA |
| I—Hodgson and Jones [1985] | Styrene manufacturing | 622 | ≥1 year | 0.49d (0.082–1.61) | Not reported | Exposure levels not reported but believed exposures would have been <100 ppm with isolated excursions to higher levels during certain activities | NA |
| J—Coggon et al. [1987] | Glass-reinforced plastics manufacturing | 7,949 | ≥1 day | 0.70 (0.53–0.90) | Not reported | High-exposure category; mean 8-hr TWA at 5 of the 8 factories after 1975, 40–100 ppm | NA |
| J—Coggon et al. [2015] | Glass-reinforced plastics manufacturing | 7,970 | 0.93 (0.83–1.03) | Not reported | SMRs (95%CI) for respiratory diseases for all workers and workers with more than background exposure to styrene, by time period: (i) 1946–2012, 0.93 (0.83–1.03) and 0.97 (0.85–1.11); (ii) 1991–2012, 1.20 (1.06–1.35) and 1.26 (1.08–1.45) | ++ | |
| K—Wong [1990] | Reinforced plastics and composites manufacturing | 15,908 | ≥6 months | 0.52° (P < 0.05) | 1.18c,i (NS) | (i) SMR for emphysema by duration of employment: <1 year: 1.28, NSc; 1–2 years: SMR, 3.75, NSc; 2–5 years: 0.83, NSc; >5 years: SMR, 0.43, NSc; (ii) SMR for emphysema by level of exposure potential: low-exposure: 1.22, NSc; high-exposure, 1.50, NSc | + |
| K—Wong et al. [1994]; Wong and Trent [1999] | Reinforced plastics and composites manufacturing | 15,826 | 1.21 (0.98–1.48) | 1.27h (0.81–1.91) | (i) SMR for other NMRD, 1.41, (95%CI, 1.05–1.85); (ii) SMR for bronchitis, emphysema, asthma by job category (minimum >2 years): open mold processing, 2.38, NSc; mixing and closed mold processing, 2.62, NSc; finish and assembly, 1.14, NSc; plant office and support, 0.42, NSc; maintenance and preparation, 1.11, NSc; supervisory and professional, 0.90, NSc | ++ | |
| K—Collins et al. [2013] | Reinforced plastics and composites manufacturing | 1.15 (1.05–1.27) | 1.35h (117–1.56) | (i) SMR for emphysema, 1.30 (95%CI, 0.96–1.71); (ii) mortality from bronchitis, emphysema, and asthma not associated with increased days of peak styrene exposure (≥15 min above 100 ppm) | ++ | ||
| L—Okun et al. [1985] | Boat manufacturing | 5,201 | ≥1 day | 0.82d (0.36–1.63) | Not reported | (i) High-exposure (mean exposures, 42.5 ppm [company A], 71.7 ppm [company B]; (ii) low-exposure included workers who never worked in high exposure departments and considered to have minimal exposure; (iii) SMR (95%CI) for NMRD by exposure category: high-exposure, 1.54d (0.26–5.08); low-exposure, 0.69d (0.25–1.54) | + |
| L—Ruder et al. [2004] | Boat manufacturing | 1.14 (0.88–1.46) | Not reported | SMRs (95%CI) for selected diseases among high-exposure cohort: (i) NMRD, 2.07 (1.24–3.23); (ii) pneumoconiosis and other respiratory diseases, 2.54 (1.31–4.44) | +++ | ||
| L—Ruder et al. [2016] | Boat manufacturing | 1,678 | ≥1 year | 0.99 (0.75–1.28) | 1.15 (0.81–1.58) | Using entire 5,201 worker cohort, SMRs (95%CI) for selected diseases among potential high-exposure subcohorts with tenure <1 year and ≥1 year, respectively: (i) NMRD, 1.99 (1.38–2.79) and 1.64 (0.96–2.63); (ii) COPD, 2.60 (1.70–3.81) and 2.02 (1.08–3.46) | +++ |
| M—Cowles et al. [1994] | Plastics and resins manufacturing | 343 | ≥1 year | 0 deaths | Not reported | (i) Research and development facility operational 1962–1975; (ii) no exposure levels reported | NA |
CI, confidence interval; COPD. Chronic obstructive pulmonary disease; NA, no association; NMRD, non-malignant respiratory diseases; NS, non-significant (P ≥ 0.05); ppm, parts per million; RR, relative risk; SMR, standardized mortality ratio; TWA, time-weighted average.
a
Strength of evidence for positive association: +++, strong; ++, intermediate; +, suggestive; NA, no association; see Table I for definitions.
b
Proportional mortality ratio calculated using Federal Republic of Germany's general population.
c
Confidence interval not reported.
d
Standardized mortality ratio and 95% confidence interval calculated from reported data using http://openepi.com
e
Standardized mortality ratio calculated for bronchitis.
f
Standardized mortality ratios presented for 3 of 10 plants included in study where styrene exposure occurred.
g
Standardized mortality ratio calculated for non-malignant respiratory disease excluding pneumonia and influenza.
h
Standardized mortality ratio calculated for bronchitis, emphysema, and asthma.
i
Standardized mortality ratio calculated for emphysema.
j
Males only when both males and females included in study.