Exposure to Biohazards in Wood Dust: Bacteria ...

Applied Occupational and Environmental Hygiene

ISSN: 1047-322X (Print) 1521-0898 (Online) Journal homepage: http://www.tandfonline.com/loi/uaoh20

Exposure to Biohazards in Wood Dust: Bacteria, Fungi, Endotoxins, and (1 3)-beta-D-Glucans K. Udeni Alwis , John Mandryk & Ailsa D. Hocking To cite this article: K. Udeni Alwis , John Mandryk & Ailsa D. Hocking (1999) Exposure to Biohazards in Wood Dust: Bacteria, Fungi, Endotoxins, and (1 3)-beta-D-Glucans, Applied Occupational and Environmental Hygiene, 14:9, 598-608, DOI: 10.1080/104732299302404 To link to this article: http://dx.doi.org/10.1080/104732299302404

Published online: 30 Nov 2010.

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Applied Occupational and Environmental Hygiene Volume 14(9): 598–608, 1999 Copyright ° c 1999 Applied Industrial Hygiene 1047-322X /99 $12.00 + .00

Exposure to Biohazards in Wood Dust: Bacteria, Fungi, Endotoxins, and (1! 3)-¯-D-Glucans¤ K. Udeni Alwis,1 John Mandryk,2 and Ailsa D. Hocking 3 1

Department of Public Health and Community Medicine, University of Sydney, Sydney, Australia; Epidemiology Unit, National Occupational Health and Safety Commission, Sydney, Australia; 3 Food Science Australia, Sydney, Australia

Downloaded by [Stephen B. Thacker CDC Library] at 07:07 03 February 2016

2

Personal exposure to fungi, bacteria, endotoxin, and (1! 3)-¯-D-glucan was determined at different woodworking sites—logging sites, sawmills, woodchipping sites, and joineries. Exposure levels to fungi at logging sites and sawmills were in the range of 103 –104 cfu/m3 , at the woodchipping mill, 103 –105 cfu/m3 , and at joineries, 102 –104 cfu/m3 . Although mean endotoxin levels were lower than the suggested threshold value of 20 ng/m3 , some personal exposures at sawmills and a joinery exceeded the standard. The geometric mean personal (1! 3)-¯-D-glucan exposure level at the woodchipping mill was 2.32 ng/m3 , at sawmills, 1.37 ng/m3 , at logging sites, 2.02 ng/m3 , and at joineries, 0.43 ng/m3 . Highly signi cant associations were found between mean personal inhalable endotoxin exposures and Gramnegative bacteria levels ( p < 0.0001), and mean personal inhalable (1! 3)-¯-D-glucan exposures and fungi levels ( p = 0.0003). The prevalence of cough, phlegm, chronic bronchitis, nasal symptoms, frequent headaches, and eye and throat irritations was signi cantly higher among woodworkers than controls. Dose-response relationships were found between personal exposures and work-related symptoms among joinery workers and sawmill and chip mill workers. Keywords

Logging Site, Sawmill, Woodchipping Mill, Joinery, Wood Dust, Fungi, Gram-Negative Bacteria, Endotoxin, (1! 3)-b -D-Glucan, Work-Related Symptoms

Exposure to organic dust can cause adverse health effects such as organic dust toxic syndrome (ODTS), bronchitis, asthma, hypersensitivity pneumonitis (extrinsic allergic alveolitis [EAA]), and mucous membrane irritation (MMI).(1)

¤

The views expressed in this article are those of the authors and do not necessarily re ect those of the University of Sydney, National Occupational Health and Safety Commission, or Food Science Australia.

598

Endotoxins of Gram-negative bacteria and the allergenic fungi which grow on wood are reported to be the main hazardous agents found in wood processing workplaces.(2) Chip piles and wood dust provide an easily accessible food supply for woodattacking microorganisms because the wood is nely divided and the protective lignin shield around the cellulose would often be broken. (3) Gram-negative bacteria and their endotoxins are ubiquitous in nature, and are commonly found in agricultural industries that generate large amounts of organic dust. Symptoms suggestive of exposure to airborne endotoxins that are the toxic lipopolysaccharide (LPS) components of Gram-negative bacteria are chest tightness, cough, shortness of breath, fever, and wheezing.(4) EAA in woodworkers is caused primarily by inhalation of the spores of contaminating fungi, but inhaled wood dust may exert a synergistic effect.(5) ODTS has been described in Swedish sawmills(6) and Norwegian sawmills(7) where the fungal spore concentrations were higher than 107 cfu/m3 . A fungal constituent, (1! 3)-b -D-glucan, is a potential biological agent found in organic dust. It is an in ammatory agent that depresses the formation of antibodies and is known to react synergistically with endotoxin or other in ammatory agents.(8) (1! 3)-b -D-glucan is probably an important agent for the development of allergic alveolitis.(9) Indoor air studies have shown dose-response relationships between levels of (1! 3)-b -Dglucan and eye and throat irritation, dry cough and itchy skin,(10) intensity of subjective throat irritation, and increase in airway responsiveness. (11) This article describes the rst comprehensive study of organic dust exposure in the wood processing industry in Australia. The ndings should be useful for assessing the impact of biohazards on the health of woodworkers and implementing control measures to reduce exposure. METHODS Two logging sites, four sawmills, one woodchipping mill, and ve joineries located in New South Wales, Australia, were investigated (Table I).

599


EXPOSURE TO BIOHAZARDS IN WOOD DUST

Dust Sampling Personal dust monitoring was conducted for both airborne inhalable dust and respirable dust. The Casella-seven-hole samplers (modi ed UKAEA)(12) and Casella-Higgins-cyclone samplers were used for inhalable and respirable sampling, respectively. The ow rates of the portable pump (Gilian, model HFS 513A, Gilian Instruments Corporation, St. Petersburg, FL, United States) was calibrated to 2 L/min (using the ow rate calibrator, Ametek, Mans eld & Green Division, Largo, FL, United States) for inhalable dust sampling(13) and 1.9 L/min for respirable dust sampling(14) according to Standards Australia. Duration of sampling was 6–8 hours except at logging sites (» 4 hr). All the job titles (woodworking ) were sampled. Polycarbonate lters (25 mm, 0.8 l m, Millipore) were used as the collection media because high extractability of endotoxins using such lters has been reported by previous studies.(15) After weighing, the lters were extracted with 2.5–20 ml of endotoxin/glucan free water (depending on the weight of dust)(15) for 60 min at room temperature, followed by centrifugation of the decanted uid for 10 min at 1000 £ g. (16) The supernatant was analyzed separately for endotoxin and glucan using quantitative end-point chromogenic limulus assay,(17) using endotoxin-speci c (endospecy test kit, standard endotoxin -

E. coli 0111:B4 [Westphal], Seikagaku Company, Japan) and glucan-speci c (Gluspecy test kit, standard (1! 3)-b -D-glucan pachyman, Seikagaku Company, Japan) lysates, respectively. Sterile polystyrene(18) tubes were used for the extraction and chemical assay. For each assay, blank lters were utilized as controls. Sampling of Airborne Microorganisms Personal samples of airborne bacteria and fungi were collected using pre-sterilized, three-piece cellulose-ester membrane lter cassettes (37 mm, 0.45 l m, Millipore) connected to a constant ow personal pump calibrated to 1.5 L/min. The duration of sampling was 4–6 hours. Microorganisms were extracted from the collected lter cassettes using a suspension uid (0.1% bacteriological peptone with 0.05% Tween 80 and 2% inositol) as described by Eduard et al. (1990).(19) Serial dilutions of the suspension were then prepared using 1/4-strength Ringer’s solution (Oxoid, Basingstoke, United Kingdom) and 0.1 ml of the dilutions were plated in different media. The plates were incubated at two temperatures (25±C and 40±C). For the isolation of fungi, 2-percent malt extract agar; for xerophilic fungi, dichloran-glycerol agar (Oxoid, United Kingdom); for bacteria and actinomycetes, one-half-strength nutrient agar (Oxoid,

TABLE I Description of work sites Work site

Type of wood

Common name of major species processed

Product

Number of workers employed

Logging site A Logging site B Sawmill CN (green mill & chip mill) Sawmill DI (dry mill) Sawmill EN (green mill & chip mill) Sawmill F (green millN & dry millE ) Wood chipping mill GN Joinery HI Joinery IE Joinery JI

Hard Hard Hard

Eucalyptus Eucalyptus Eucalyptus

Logs for sawmilling Logs for sawmilling Green timber and wood chips

4 4 25

Hard

Eucalyptus

20

Hard

Eucalyptus

Kiln-dried timber for ooring Green timber and wood chips

Hard

Eucalyptus

23

Hard

Eucalyptus

Green timber and kiln-dried timber (for ooring) Wood chips

Hard and soft Soft Hard and soft

Staircases Window frames Moldings

12 40 12

Joinery KI Joinery LI

Hard and soft Mostly hard

Radiata pine, meranti, MDF Western red cedar Sugar pine, radiata pine, meranti brush box Radiata pine, meranti, MDF Tasmanian oak, American oak, jarrah, Tasmanian blackwood, brush box

Staircases and handrails Pantry cupboard doors

18 11

E

Exhaust ventilation system—ef cient. Exhaust ventilation system—inef cient and inadequate. N No exhaust ventilation system. MDF: Medium-density ber. I

26

30

600

K. U. ALWIS ET AL.


United Kingdom); and for Gram-negative bacteria, a selective medium, violet red bile glucose agar (Amyl media, Australia) was used. The colonies were identi ed by their appearance and microscopic morphology from standard texts.(20¡ 22) Aspergillus and Penicillium species were identi ed using media and methods described by Pitt and Hocking(23) with reference to more detailed tests where necessary.(24¡ 26) Work-Related Symptoms The “Organic Dusts Questionnaire,”(27) together with appropriate questions on respiratory, nasal, and conjunctival symptoms from the British Medical Research Council’s respiratory questionnaire, (28) were used to assess work-related symptoms. The “Organic Dusts Questionnaire” includes occupational history, personal protective equipment, work-related symptoms, allergy, and smoking status. One hundred ninety- ve woodworkers participated in the questionnaire study. The maintenance workers at the woodworking sites were used as controls because their ethnic and social backgrounds were similar to those of the woodworkers. The job tasks of the maintenance workers did not involve wood dust exposure under normal circumstances. Data Analysis Correlations among personal exposures (Pearson’s R) were obtained using the natural logarithms of exposure (as the data were log-normally distributed). Correlation analyses were performed using the GraphPad InStat (version 2.04a, United States) statistical program. For descriptive statistics, and the questionnaire analyses, SPSS statistical software (SPSS for Windows, version 6.1.3, SPSS Inc., United States) was used. Work-related symptoms were adjusted for age and smoking by logistic regression analyses. For the comparison of work-related symptoms among woodworker s and controls chi-square analysis was used. RESULTS None of the machines at the green mills was tted with an exhaust ventilation system. At sawmill D, the use of aging equipment, poor maintenance of the local exhaust ventilation system, and leakage of dust from the joints of the central exhaust ventilation system into the working environment resulted in high dust exposures. At sawmill FD , all the static machines were effectively exhaust ventilated. The high dust exposure levels found among joineries (except joinery I), were due to inadequate and inef cient ventilation systems, poor maintenance of the ventilation systems, the use of handheld tools, and the use of compressed air to remove dust from the surfaces, timber, oor, and clothing. At joinery I, all the static machinery and portable tools were tted with exhaust ventilation systems and vacuum cleaning was employed to remove dust from the surfaces of machinery and the oor. Information on wood dust exposure levels by job titles, exhaust ventilation systems, and determinants of wood dust exposures at the above work sites are reported in detail in another publication.(29)

Exposure to Fungi, Bacteria, Endotoxins and (1! 3)-¯-D-Glucans Table II presents the personal mean concentrations of fungi, total bacteria, and Gram-negative bacteria at each work site. At logging sites, Aspergillus fumigatus and Penicillium spp. were the predominant fungi. Among sawmills and the woodchipping mill, Penicillium spp. were the predominant species. The lowest concentrations of total fungi were found at sawmill Fd (3 £ 103 cfu/m 3 ) and joinery I (4 £ 103 cfu/m3 ), where ef cient dust extraction systems had been installed. Dust exposures were also relatively lower (sawmill FD - 1.16 mg/m3 , joinery I - 0.6 mg/m3 ) for these latter sites (Table III). Mean personal exposure to fungi was highest at the woodchipping mill (74 £ 103 cfu/m3 ). High concentrations of Aspergillus fumigatus were found at logging sites (logging site A - 40 £ 103 cfu/m3 ; logging site B - 18 £ 104 cfu/m 3 ) where debarking was carried out, at woodchipping mill G (16 £ 103 cfu/m 3 ), and at joinery H (10 £ 103 cfu/m3 ). High airborne levels of Penicillium spp. were found at woodchipping mill G (41£ 103 cfu/m3 ), at sawmill C (38£ 103 cfu/m3 ), and at sawmill E (30 £ 103 cfu/m3 ). Among Penicillium species identi ed in personal samples collected at each site, P. glabrum (previously known as P. frequentans) was the predominant species. P. chrysogenum was also found at most of the sites at low concentrations. High mean airborne levels of Aureobasidium pullulans were found at sawmill E (12£ 103 cfu/m 3 ) and sawmill FG (13 £ 103 cfu/m3 ). The variability of personal fungi exposure levels expressed by the geometric standard deviation (GSD) was 3.72 at the logging sites, 2.77 at the sawmills, 3.41 at the woodchipping mill, and 3.18 at the joineries. A high variability in personal exposure to Gram-negative bacteria was found at the logging sites (GSD = 7.11) compared with the sawmills (GSD = 3.84), the woodchipping mill (GSD = 3.52) and the joineries (GSD = 4.55). High mean personal exposure levels of Gram-negative bacteria were found at the green mills (sawmills C and E - 12 £ 103 cfu/m 3 ), the woodchipping mill (14 £ 103 cfu/m3 ), and the joinery K (13 £ 103 cfu/m3 ). A work group has reported that in any environment, the total number of Gram-negative bacteria should not exceed 103 cfu/m 3 .(30) High exposures to endotoxin and (1! 3)-b -D-glucan were found in the inhalable fraction relative to the respirable fraction (Tables III and IV). Some of the inhalable exposures found at sawmills (sawmills C, E, and F) and a joinery ( joinery H) (Table III) exceeded the threshold limit value for endotoxin(31) (20 ng/m3 for an 8-hr shift). Mean (1! 3)-b -D-glucan exposures were much lower at joineries than at sawmills, and wood chipping and logging sites. The exposure data were log-normally distributed. Signi cant positive correlations were found between mean personal inhalable endotoxin exposures with Gram-negative bacteria ( p < 0.0001) and mean inhalable glucan exposures with total fungi levels ( p = 0.0003) (Table V). Also, the correlations between mean personal respirable endotoxin exposures versus Gram-negative bacteria levels ( p = 0.0045), and respirable

Microorganism

B

A

nB :

B

C

D

E

FD

FG

FDG

G

H

I

J

K

L

.48 .88

.89 3.93 4.17

33.85 9.96 6.95

.89

13.51

13.00 0.50 0.06

.06 64.26 8.86 5.89

18.09

39.86 1.56 0.23 37.96 .10 .17 2.46 .76 1.34 .41 .18 .14 50.16 21.43 11.65

5.16 1.48

.47 .55 26.46 5.19 3.30

6.45 .61 .17 .22 8.07 2.32 .38 3.07 2.60 1.55

1.63 .63 .68 .32 30.14 3.02 .12 1.14 12.15 2.47 1.50 .25 .12 54.17 22.40 11.58 3.34 9.19 5.58

.63

.11 .11

1.69 .22

.58

41.21 17.56 7.81

.27

21.63 .85 .19 .24 13.42 .94

3.26 .41

26.65 14.34 6.95

.40

13.96 .61 .11 .19 8.30 .58

2.25 .25

.16 74.06 20.56 14.13

.20 .22

16.27 .20 .31 .19 41.44 15.07

.07 .34 13.59 25.72 15.13

.66 1.41 .18 .19 .44

10.30

.11 .34 1.27 3.95 2.86 .44

.27

.46 .10

.99 .27 .14

.08 16.95 3.00 1.53

.94

9.98 1.48 .15 .10

.71

3.51

.11 .11 7.75 23.00 12.86

.37

1.46 .40 .08 2.97

1.99 .20 .06

.79 19.20 4.40 2.08

10.75 3.46 .17 .41 .90 .13

2.34 .18 .07

(n = 3) (n = 3) (n = 15) (n = 10) (n = 12) (n = 5) (n = 8) (n = 13) (n = 10) (n = 10) (n = 5) (n = 6) (n = 9) (n = 11)

A

TABLE II Mean personal exposure levels of microorganisms (£ 103 cfu/m3 ) by work siteA


A, B - Logging sites; C–F - Sawmills (FD -Dry mill, FG -Green mill, FDG -Both dry mill and green mill); G - Wood chipping mill; H–L - Joineries. Number of workers sampled.

Fungi: Aspergillus fumigatus Aspergillus versicolor Aspergillus spp. (other) Eurotium spp. Penicillium spp. Paecilomyces spp. Alternaria spp. Cladosporium spp. Aureobasidium pullulans Fusarium spp. Acremonium spp. Yeast Other fungi Total fungi Bacteria Gram-negative bacteria

601

602

0.50 0.68 0.58 0.83 2.99 12.32 2.02 4.81 3.17 15.33 0.68 2.53 11.35 5.33 7.59

Logging site A Logging site B Logging site (total) Sawmill C Sawmill D Sawmill E Sawmill FE Sawmill (total) Wood chipping mill G Joinery H Joinery I Joinery J Joinery K Joinery L Joinery (total)

0.49 0.67 0.56 0.74 1.91 2.44 1.68 1.59 2.86 11.47 0.61 1.80 7.32 4.84 3.68

GMB 1.23 (0.38–0.59, n 1.22 (0.57–0.84, n 1.29 (0.38–0.84, n 1.60 (0.25–2.63, n 2.62 (0.55–11.22, n 5.42 (0.26–74.05, n 1.89 (0.56–4.55, n 3.19 (0.25–74.05, n 1.66 (1.80–5.66, n 2.02 (4.85–50.65, n 1.68 (0.21–1.31, n 2.47 (0.37–7.79, n 2.86 (0.73–35.86, n 1.57 (2.60–10.90, n 3.67 (0.21–50.65, n

GSDC = = = = = = = = = = = = = = =

4)D 3) 7) 22) 29) 25) 17) 93) 4) 13) 12) 12) 18) 11) 66) 1.76 1.30 1.56 16.83 2.27 21.08 8.09 12.97 3.52 9.80 0.74 2.61 6.42 2.31 4.65

AM 1.72 1.28 1.52 5.35 1.95 9.11 2.69 4.30 3.27 5.98 0.37 2.21 5.22 2.13 2.41

GM 1.28 (1.29–2.28, n 1.27 (0.99–1.56, n 1.32 (0.99–2.28, n 6.12 (0.19–78.40, n 1.78 (0.53–5.59, n 4.66 (0.39–73.63, n 4.42 (0.51–40.56, n 4.77 (0.19–78.40, n 1.55 (2.00–4.87, n 3.20 (0.60–27.88, n 3.41 (0.10–2.36, n 1.78 (1.30–7.04, n 1.88 (2.37–17.88, n 1.52 (1.18–4.72, n 3.66 (0.10–27.88, n

B

GSD = = = = = = = = = = = = = = =

4) 3) 7) 22) 20) 24) 17) 83) 4) 13) 12) 12) 18) 11) 66)

3.35 2.39 2.94 4.33 0.60 4.78 2.70 3.28 4.63 0.51 0.33 0.71 0.35 1.09 0.57

1.98 2.07 2.02 2.13 0.49 2.75 0.92 1.37 2.32 0.50 0.33 0.59 0.30 0.49 0.43

GM

Inhalable (1! AM

3)-b -D-glucan

Inhalable endotoxin (ng/m3 )

Arithmetic mean. Geometric mean. C Geometric standard deviation. D (Range, number of workers sampled). E Green mill—2.32 mg/m3 (GM) (1.03–4.55, n = 9); Dry mill - 1.16 mg/m3 (GM) (0.56–2.40, n = 8).

A

AMA

Work site

Inhalable dust (mg/m3 )

TABLE III Mean personal inhalable exposure levels to dust, endotoxin, and (1!


3.62 (0.47–7.62, n 2.02 (0.95–3.74, n 2.71 (0.47–7.62, n 3.98 (0.25–11.74, n 1.90 (0.20–1.46, n 4.02 (0.16–9.67, n 5.42 (0.16–7.65, n 4.42 (0.16–11.74, n 4.71 (0.27–10.40, n 1.22 (0.43–0.71, n 1.11 (0.28–0.38, n 1.86 (0.31–1.62, n 1.73 (0.19–0.79, n 4.01 (0.11–3.60, n 2.01 (0.11–3.60, n

GSD = = = = = = = = = = = = = = =

4) 3) 7) 13) 11) 16) 14) 54) 4) 10) 8) 6) 8) 7) 39)

3)-b -D-glucan (ng/m3 )

603

0.03 0.04 0.04 0.26 0.52 0.31 0.32 0.37 0.28 1.01 0.16 0.63 0.64 0.73 0.67

AMA 0.03 0.04 0.03 0.23 0.49 0.20 0.27 0.29 0.26 0.80 0.13 0.59 0.54 0.70 0.48

GMB

B

Arithmetic mean. Geometric mean. C Geometric standard deviation. D (Range, number of workers sampled).

A

Logging site A Logging site B Logging site (total) Sawmill C Sawmill D Sawmill E Sawmill F Sawmill (total) Wood chipping mill G Joinery H Joinery I Joinery J Joinery K Joinery L Joinery (total)

Work site 1.00 (n = 2) 1.44 (0.03–0.05, n 1.29 (0.03–0.05, n 1.90 (0.12–0.41, n 1.41 (0.28–1.05, n 2.66 (0.05–0.98, n 2.02 (0.08–0.54, n 2.17 (0.05–1.05, n 1.71 (0.12–0.40, n 2.06 (0.33–2.55, n 2.03 (0.03–0.41, n 1.44 (0.41–0.99, n 2.02 (0.19–1.13, n 1.36 (0.49–1.18, n 1.70 (0.03–2.55, n

GSDC

Respirable dust (mg/m3 )

= = = = = = = = = = = = = =

2)D 4) 6) 12) 11) 8) 37) 4) 12) 8) 5) 7) 7) 39)

0.16 0.13 0.14 2.03 0.18 1.85 1.20 1.40 0.83 0.91 0.14 0.30 0.43 0.25 0.47

AM 0.15 0.13 0.14 0.87 0.16 1.45 0.50 0.65 0.81 0.71 0.13 0.29 0.36 0.24 0.33

GM 1.44 (0.12–0.20, n 1.12 (0.12–0.14, n 1.28 (0.12–0.20, n 5.76 (0.1–5.25, n 1.49 (0.11–0.33, n 2.13 (0.61–4.45, n 5.02 (0.1–2.80, n 4.10 (0.1–5.25, n 1.35 (0.49–1.02, n 2.09 (0.30–2.04, n 1.27 (0.1–0.2, n 1.36 (0.18–0.40, n 1.92 (0.15–0.83, n 1.36 (0.19–0.44, n 2.24 (0.1–2.04, n

GSD = = = = = = = = = = = = = = =

2) 2) 4) 6) 6) 11) 8) 31) 4) 12) 8) 5) 7) 7) 39)

0.76 0.39 0.57 0.52 0.15 0.40 0.52 0.40 0.85 0.12 0.11 0.21 0.12 0.18 0.14

AM

0.75 0.36 0.52 0.31 0.14 0.29 0.33 0.26 0.76 0.12 0.11 0.20 0.12 0.16 0.14

GM

Respirable (1!

3)-b -D-glucan

Respirable endotoxin (ng/m3 )

TABLE IV Mean personal respirable exposure levels to dust, endotoxin, and (1!


2.42 (0.64–0.88, n 1.69 (0.25–0.53, n 1.70 (0.25–0.88, n 2.25 (0.1–1.56, n 1.35 (0.1–0.25, n 2.47 (0.1–1.03, n 2.96 (0.1–1.24, n 2.53 (0.1–1.56, n 1.64 (0.49–1.76, n 1.19 (0.1–0.15, n 1.15 (0.1–0.14, n 1.16 (0.18–0.25, n 1.12 (0.1–0.14, n 1.69 (0.1–0.35, n 1.39 (0.1–0.35, n

GSD = = = = = = = = = = = = = = =

2) 2) 4) 6) 6) 10) 6) 28) 4) 6) 5) 4) 5) 5) 25)

3)-b -D-glucan (ng/m3 )

604

K. U. ALWIS ET AL.


glucan exposures versus total fungi levels ( p = 0.0046) were signi cant. Work-Related Symptoms Only 10 percent of the workers observed in this study wore appropriate respirators approved for wood dust. Furthermore, the workers who did use respirators wore them on average less than 50 percent of the time during a shift. The prevalence of cough, phlegm, chronic bronchitis (persistent cough and phlegm for more than 3 months per year, for more than 2 years), nasal symptoms, frequent headaches, eye irritation, and throat irritation was signi cantly high among woodworkers compared with controls (Table VI). The prevalence of cough, phlegm, wheezing, regular blocked nose, regular runny nose, sinus problems, and throat irritation was signi cantly high among joinery workers compared with sawmill and chipmill workers. Whereas the prevalence of eye irritation and regular ear in ammation and infections was high among sawmill and chip mill workers, nasal problems were high in both groups compared with controls. Both joinery workers and sawmill and chip mill workers showed signi cant correlations between mean personal exposures and work-related symptoms after controlling for age and smoking (Table VII). Although personal exposure levels of respirable dust, (1! 3)-b -glucans, and endotoxins were very low, they still had signi cant relationships with respiratory symptoms, throat irritation, and ear problems among both groups. It has been reported that an increase in symptomology occurs when the (1! 3)-b -D-glucan exposures are above 10 ng/m3 .(11) In the present study, a majority of the inhalable and all the respirable (1! 3)-b -D-glucan exposures were well below 10 ng/m3 . Studies on sick buildings have also reported dose-response relationships between low (1! 3)-b -D-glucan exposures and eye and throat irritation, dry cough and itchy skin,(10) and throat irritation and airway responsiveness.(11) In the present study, dose-response relationships were found between mean personal

respirable (1! 3)-b -D-glucan exposures with chronic bronchitis (OR = 3.73), throat irritation (OR = 2.79), and regular ear in ammation and infections (OR = 33.22) among sawmill and chip mill workers. A signi cant correlation was found between mean personal inhalable (1! 3)-b -D-glucan exposures and chronic bronchitis among joinery workers (OR = 20). Frequent ear in ammation and ear infections were also signi cantly correlated with mean personal respirable glucan levels (OR = 29.99) among joinery workers. Signi cant correlations were also found between mean personal endotoxin exposures and chronic bronchitis. Relationships were found between mean personal exposures to fungi and Gram-negative bacteria with respiratory, throat, and ear problems among woodworkers. DISCUSSION Personal exposure levels to fungi at logging sites and sawmills were in the range 103 –104 cfu/m 3 , at the woodchipping mill, 103 –105 cfu/m 3 , and at joineries, 102 –104 cfu/m3 . A total spore concentration higher than 109 spores/m3 or higher than 107 cfu/m 3 is regarded as hazardous.(30) However, an insidious subacute development of allergic alveolitis can also result from prolonged exposure to low concentrations of fungi.(32) Aspergillus fumigatus and Penicillium spp. were the predominant fungi at the logging sites. Among sawmills and the woodchipping mill, Penicillium spp. were the predominant species. The fungi implicated in extrinsic allergic alveolitis (EAA) are mainly the dry spored species, which produce abundant spores of respirable size, less than 5 l m (Aspergillus and Penicillium species).(33) EAA can also be caused by slimy spored species such as Graphium sp., Aureobasidium pullulans, Phoma violacea and Acremonium spp. Penicillium glabrum has been implicated in the etiology of suberosis, a form of EAA caused by inhaling dust from mouldy cork, which was reported among workers at a Portuguese cork factory.(34) Non-occupational allergic alveolitis caused by Penicillium chrysogenum due to faulty installation of central heating

TABLE V Signi cant correlations (Pearson’s R) among mean personal exposure levels of dust, bacteria, fungi, endotoxin, and (1! 3)-b -D-glucan) (n = 62–160)

Inhalable dust Respirable dust Inhalable endotoxin Respirable endotoxin Total bacteria Inhalable glucan Respirable glucan A

Respirable dust

Inhalable endotoxin

Respirable endotoxin

Total bacteria

Gram-negative bacteria

Inhalable glucan

Respirable glucan

0.81 B

0.58 A 0.41

0.41 0.37 0.84C

0.58 A 0.39 0.84 C 0.91 C

0.58A 0.33 0.90 C 0.75B 0.90 C

¡ 0.58 A ¡ 0.52 0.31 0.38 0.21

¡ 0.60A ¡ 0.55 0.11 0.45 0.06 0.86 C

p < 0.05. p < 0.01. C p < 0.001 (Two-tailed p value). B

Fungi ¡ 0.21 ¡ 0.25 0.50 0.46 0.27 0.86 C 0.76 B

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has been reported.(35) Fuel-chip-induced hypersensitivity pneumonitis (EAA),(36) woodman’s disease,(37) hypersensitivity pneumonitis from cutting live trees, and cheese worker’s hypersensivity pneumonitis,(38) also caused by Penicillium species have also been reported. Aureobasidium pullulans is considered the cause of sequoiosis, EAA associated with redwood sawdust (Sequoia sempervirens).(39) Swedish studies(40,41) have identi ed kiln drying as the cause of high mold exposure at trimming departments in their sawmills. In contrast, in our study, the sawmills employing a kiln drying process had low levels of mold exposure (Sawmills D and Fd ). The low levels of fungi observed may be due to the type of wood

or the air drying process prior to kiln drying, which reduces the moisture content to a considerable extent, preventing excessive growth of microorganisms. Personal exposure levels to microorganisms were also very low at those workplaces (sawmill FD and joinery I) with ef cient dust control systems. Although the mean endotoxin levels were lower than a threshold limit value for endotoxin (20 ng/m3 ), some personal exposures at sawmills and joineries exceeded the TLV. The mean exposure levels of (1! 3)-b -D-glucan were higher at the woodchipping mills, green mills, and the logging sites compared with the joineries. Signi cant correlations were found between personal airborne mean inhalable endotoxin exposures and

TABLE VI Percentage prevalence of work-related symptomsA among woodworkers and controls

No.: Age (yr) C Years exposed (yr)C Smoking Respiratory Asthma Dry cough Cough Phlegm Chronic bronchitis Breathlessness Wheezing Chest tightness Dyspnea Nasal Regular dry nose Regular blocked nose Regular itching or bleeding nose Regular runny nose Regular sneezing Sinus problems Other Flu-like symptoms Frequent headaches Conjunctivitis Eye irritation Regular ear in ammation/infections Throat irritation Vertigo Nausea Skin problems A

Sawmill and chip mill

Joinery

WoodworkersB

Controls

108 38 § 12.8 8 § 8.7 40%

82 36 § 14.7 12 § 12.1 23%

195 37 § 13.6 10 § 10.5 33%

34 40 § 11.3 9 § 7.7 30%

8.3 24.1 58.6 F 46.0 D 29.6 D 18.5 15.7 21.3 2.8

13.4 23.2 62.2 F 67.1 F 31.7 18.3 32.9 D 36.6 7.3

10.8 23.1 61.0F 61.5F 30.3D 17.4 22.6 27.2 4.6

5.9 23.5 23.5 23.5 11.8 14.7 11.8 17.6 0.0

32.4 46.3 D 25.9 42.6 E 44.4 E 29.6 D

35.4 63.4 F 22.0 51.2 F 46.3 E 35.4 D

33.3 42.6 23.6 54.4F 52.3F 31.8D

20.6 29.4 14.7 17.6 14.7 11.8

29.6 59.3 F 3.7 53.7 F 16.7 D 22.2 D 4.6 5.6 15.7

29.3 57.3 F 7.3 29.3 8.5 51.2 F 3.7 11.0 25.6

28.7 59.0F 5.1 37.9D 13.3 32.8F 4.1 7.7 20.0

14.7 17.6 2.9 17.6 2.9 5.9 5.9 0.0 14.7

Adjusted for age and smoking by logistic regression. Including workers at logging sites. C Mean § SD. D p < 0.05, E p < 0.01, F p < 0.001 (Chi-square analysis; compared with controls). B

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TABLE VII Correlations among mean personal exposures and work-related symptoms among joinery workers and sawmill and chip mill workers Group of workers A Joinery


Sawmill/chip mill Joinery Total Joinery Total Joinery Sawmill/chip mill Joinery Sawmill/chip mill Total

Joinery Sawmill/chip mill

Total

Joinery Sawmill/chip mill

Total

Joinery Sawmill/chip mill Total A

Symptom B Bronchitis Phlegm Ear in am. Freq. headache Bronchitis Eye irritation Bronchitis Phlegm Ear in am. Throat irritation Bronchitis Bronchitis Ear in am. Bronchitis Bronchitis Ear in am. Ear in am Throat irritation Wheezing Ear in am. Bronchitis Ear in am. Throat irritation Chest tightness Ear in am. Wheezing Bronchitis Phlegm Breathlessness Bronchitis Ear in am. Ear in am. Throat irritation Wheezing Bronchitis Ear in am. Ear in am.

Exposure Inh. dust

Resp. dust Inh. endotoxin

Resp. endotoxin

Inh. glucan

Resp. glucan

Fungi

Gram-negative bac.

Prevalence odds ratioC 2.26 (0.19–4.22) 1.79 (1.05–3.04) 5.50 (1.07–28.29) 2.76 (1.01–7.57) 3.12 (1.23–7.96) 1.94 (1.11–3.37) 2.32 (1.25–4.30) 1.76 (1.06–2.92) 1.81 (1.01–3.23) 1.53 (1.09–2.14) 14.27 (3.36–60.58) 2.34 (1.14–4.79) 2.90 (1.07–7.86) 20.00 (9.80–41.09) 3.09 (1.37–6.98) 7.49 (1.61–34.91) 3.13 (1.70–5.73) 1.49 (1.00–2.23) 1.58 (1.00–2.50) 29.99 (18.33–49.07) 3.73 (1.37–10.11) 33.22 (5.85–188.61) 2.79 (1.01–7.70) 1.81 (1.02–3.22) 7.29 (3.09–17.21) 2.29 (1.19–4.39) 2.95 (1.31–6.65) 2.00 (1.02–3.92) 4.77 (1.36–16.69) 2.87 (1.14–7.23) 13.32 (1.97–90.02) 2.69 (1.48–4.88) 1.56 (1.15–2.10) 1.41 (1.03–1.95) 4.16 (1.58–10.97) 5.36 (1.46–19.72) 2.78 (1.39–5.55)

p value 0.009 0.028 0.037 0.044 0.015 0.017 0.007 0.026 0.040 0.012 < 0.001 0.018 0.032 0.007 0.006 0.009 < 0.001 0.047 0.048 0.016 0.008 < 0.001 0.044 0.037 < 0.001 0.011 0.008 0.041 0.013 0.023 0.007 < 0.001 0.003 0.031 0.003 0.010 0.003

Joinery: n = 82, sawmill/chip mill: n = 108, total: n = 190. Bronchitis = chronic bronchitis. C Odds ratio (95% con dence interval) using multiple logistic models (confounders adjusted: age and smoking). p < 0.05. p < 0.01. p < 0.001. B



Gram-negative bacteria levels and mean inhalable glucan exposures with total fungi levels. The correlations between personal mean respirable endotoxin exposures versus Gram-negative bacteria levels and respirable glucan exposures versus total fungi levels were also quite signi cant. The measurement of airborne constituents, such as endotoxins from Gram-negative bacteria and (1! 3)-b -D-glucan from molds can have certain advantages compared with counting viable microorganisms, as they are often stable and can be measured over longer sampling periods.(42) Furthermore, these constituents have also been found to be of etiologic relevance. The prevalence of cough, phlegm, chronic bronchitis, frequent headaches, eye irritation, throat irritation, and nasal symptoms was signi cantly high among woodworkers compared with controls. Particle-size distribution studies have shown that the major portion of wood dust is contributed by particles larger than 10 l m in diameter, which can be easily trapped in the nasal passages.(43) Both joinery workers and sawmill and chip mill workers showed signi cant associations between personal exposures and respiratory, throat, and ear problems. Joinery workers showed signi cant associations between personal exposures (inhalable and respirable dust, inhalable and respirable endotoxin, inhalable glucan, fungi, and Gram-negative bacteria) and chronic bronchitis. Sawmill and chip mill workers showed signi cant relationships among personal exposures (respirable endotoxin, inhalable glucan, respirable glucan, and fungi) and chronic bronchitis. It has been reported that endotoxins contribute to developing chronic bronchitis among those exposed to organic dust. (44) The prevalence of chest tightness among joinery workers was 37 percent, and among sawmill and chip mill workers 21 percent. Among those having symptoms, 33 percent of joinery workers, and 52 percent of sawmill and chip mill workers reported that they had symptoms on their rst day back at work after a weekend. Monday-related chest tightness, which was initially described among cotton workers, is now known to occur in other organic dust exposures such as swine con nement buildings, poultry plants, and buildings with contaminated humidi ers.(31)

CONCLUSIONS This study has con rmed that from the tree cutting stage to the nal manufacturing stage woodworkers are exposed to wood dust of different particle sizes, concentrations, and compositions. The dose-response relationships found between personal exposures and work-related symptoms indicate that wood dust and wood-dust-associated biohazards—endotoxins, (1! 3)-b D-glucans, Gram-negative bacteria, and fungi—are potential health hazards in the woodworking industry. This is the rst comprehensive study on personal exposure to airborne biohazards associated with wood dust conducted in Australia. Further studies on immunoassay are required to determine exposure-respons e relationships together with symptoms

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to evaluate the prevalence of organic dust toxic syndrome, EAA, and other organic-dust-related diseases among woodworkers. ACKNOWLEDGMENTS The authors are grateful to the management and the employees of the companies and the contract employees at the logging sites, for their cooperation; the State Forest Authority, Kempsey and State Forest Authority, Walcha for allowing sampling at logging sites; Mr. Jim Morton, Timber Trade Industrial Association (TTIA), NSW for facilitating access to sawmills and the wood chipping mill; Mr. Warren Baker, CFMEU, for his help in getting access to joineries; Mr. John Lee and Mr. Trevor Mayhew, WorkCover Authority, for providing training and air sampling equipment for the study, and Mr. Mahinda Seneviratne, formerly of the National Occupational Health and Safety Commission, for his assistance and advice. REFERENCES 1. Donham, K.J.; Thorne, P.S.: Agents in Organic Dust: Criteria for a Causal Relationship. Am J Ind Med 25:33–39 (1994). 2. Dutkiewicz, J.; Jabionski, L.; Olenchock, S.A.: Occupational Biohazards: A Review. Am J Ind Med 14:605–623 (1988). 3. Rosell, S.E.; Abbot, E.G.M.; Levy, J.F.: Bacteria and Wood: A Review of the Literature Relating to the Presence, Action and Interaction of Bacteria in Wood. J Inst Wood Sci 6:28–35 (1973). 4. Olenchock, S.A.: Health Effects of Biological Agents: The Role of Endotoxins. Appl Occup Environ Hyg 9:62–64 (1994). 5. Halpin, D.M.G.; Graneek, B.J.; Turner-Warwick, M; et al.: Extrinsic Allergic Alveolitis and Asthma in a Sawmill Worker: Case Report and Review of the Literature. Occup Environ Med 51:160– 164 (1994). 6. Belin, L.: Clinical and Immunological Data on “Wood Trimmer’s Disease” in Sweden. Eur J Respir Dis 61 (Suppl. 107):169–176 (1980). 7. Eduard, W.; Sandven, P.; Levy, F.: Serum IgG Antibodies to Mold Spores in Two Norwegian Sawmill Populations: Relationship to Respiratory and Other Work-Related Symptoms. Am J Ind Med 24:207–222 (1993). 8. Fogelmark, B.; Goto, H.; Yuasa, K.; et al.: Acute Pulmonary Toxicity of Inhaled b -1,3-Glucan and Endotoxin. Agents Action 35:50– 56 (1992). 9. Fogelmark, B.; Rylander, R.: Lung In ammatory Cells After Exposure to Mouldy Hay. Agents Action 39:25–30 (1993). 10. Rylander, R.; Persson, K.; Goto, H.; et al.: Airborne Beta-1,3Glucan May Be Related to Symptoms in Sick Buildings. Indoor Environ 1:263–267 (1992). 11. Rylander, R.: Airway Responsiveness and Chest Symptoms After Inhalation of Endotoxin or (1! 3)-b -D-Glucan. Indoor Built Environ 5:106–111 (1996). 12. Vaughan, N.P.; Chalmers, C.P.; Botham, R.A.: Field Comparisons of Personal Samplers for Inhalable Dust. Ann Occup Hyg 34:553– 573 (1990). 13. Standards Australia: Workplace Atmospheres-Methods for Sampling and Gravimetric Determination of Inspirable Dust, Australian Standard 3640-1989 . Standards Australia, New South Wales, Australia (1989).


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