This article was downloaded by: [Michigan State University] On: 22 February 2015, At: 09:05 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

Journal of Occupational and Environmental Hygiene Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/uoeh20

Exposure to Crystalline Silica at Alberta Work Sites: Review of Controls a

b

Diane Radnoff P.Eng. M. Eng. CIH , Maria S. Todor MD MPH & Jeremy Beach MBBS MD FRCP(C)

c

a

Safe, Fair and Healthy Workplaces, Alberta Jobs, Skills, Training and Labour

b

Public Health and Preventative Medicine Resident, University of Alberta

c

Division of Preventative Medicine, University of Alberta Accepted author version posted online: 27 Jan 2015.

Click for updates To cite this article: Diane Radnoff P.Eng. M. Eng. CIH, Maria S. Todor MD MPH & Jeremy Beach MBBS MD FRCP(C) (2015): Exposure to Crystalline Silica at Alberta Work Sites: Review of Controls, Journal of Occupational and Environmental Hygiene, DOI: 10.1080/15459624.2015.1009987 To link to this article: http://dx.doi.org/10.1080/15459624.2015.1009987

Disclaimer: This is a version of an unedited manuscript that has been accepted for publication. As a service to authors and researchers we are providing this version of the accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proof will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to this version also.

PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions

ACCEPTED MANUSCRIPT Exposure to Crystalline Silica at Alberta Work Sites: Review of Controls Diane Radnoff, P.Eng., M. Eng., CIH, Safe, Fair and Healthy Workplaces, Alberta Jobs, Skills, Training and Labour Maria S. Todor, MD, MPH, Public Health and Preventative Medicine Resident, University of Alberta

Downloaded by [Michigan State University] at 09:05 22 February 2015

Jeremy Beach, MBBS, MD, FRCP(C), Division of Preventative Medicine, University of Alberta ABSTRACT From 2009 to 2013, Alberta Jobs, Skills, Training and Labour (JSTL) conducted a project to evaluate exposure to crystalline silica and assess controls to protect workers. Information on exposure results has been previously reported; this paper discusses the data collected on workplace controls. Information on work site controls was collected during exposure assessments consisting of qualitative information on controls in place and used by workers at the time of the assessments. Where there was sufficient detail, the information was further analyzed to evaluate the impact of a particular control. While many types of controls were observed, they were not always effective or in use. The control available most often was respiratory protective equipment. Generally, when respirators were used, they were correctly selected for the level of measured exposure. However, not all workers who were potentially over-exposed wore respirators at the time of the assessments. When the use of respirators was taken into account, about one third of workers were still potentially exposed over the Alberta occupational exposure limit. The industries with the highest levels of exposure tended to be those with the most unprotected workers. Issues were

1

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT identified with the use of improper work practices such as dry cleaning methods, lack of documented work procedures, poor housekeeping and lack of training which may have contributed to worker exposure levels. There is a wide range in the efficacy of controls, particularly engineering controls. Most of the literature focuses on engineering controls; however administrative controls also play a role Downloaded by [Michigan State University] at 09:05 22 February 2015

in reducing worker exposure. Data collected in this work indicated that simple changes to work procedures and behavior (such as improved housekeeping) may be effective, low-cost ways to reduce workplace exposure. More study is required to evaluate the impact and efficacy of administrative controls such as housekeeping and training. Employers must select and evaluate controls in the context of overall workplace health and safety programs and ensure that they are supported by supervision, good work practices and training.

2

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT INTRODUCTION Crystalline silica has been recognized as an important occupational hazard in many industries for centuries, and it remains a health concern for workers today[1, 2, 3, 4, 5, 6]. New exposure circumstances such as denim sandblasting, hydraulic fracturing and the increasing use of manufactured stone products mean that exposure to silica will continue to be a hazard in

Downloaded by [Michigan State University] at 09:05 22 February 2015

workplaces for the foreseeable future[7, 8, 9, 10]. Exposure to respirable crystalline silica causes a number of respiratory health effects, most notably silicosis as well as an increased risk for lung cancer[11, 12, 13]. While exposure to crystalline silica is a hazard shared by many industries and occupations, little data were available regarding exposure to crystalline silica at Alberta work sites. There were also indications that occupational disease from silica exposure was not being reported to the extent that it should be[14]. These concerns prompted Alberta Jobs, Skills, Training and Labour (JSTL) to conduct a project to evaluate exposure to crystalline silica in Alberta and to assess controls in place to protect workers. The results of this work indicated that there was a potential to exceed the Alberta occupational exposure limit (OEL) of 0.025 mg/m3 for respirable crystalline silica at many of the work sites evaluated[15]. Approximately 50% of the samples had a respirable quartz silica (silica) concentration greater than the Alberta OEL, and about 30% had concentrations greater than the National Institute of Occupational Safety and Health (NIOSH) recommended exposure limit (REL) of 0.05 mg/m3. The industries with the highest potentials for over-exposure were sand and mineral processing, followed by new commercial building construction, aggregate mining and crushing, abrasive blasting and demolition. Occupations with the highest potential for exposure to airborne respirable silica were brick layers and concrete cutting/coring/finishing

3

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT workers, equipment operators in underground mining, painters, labourers in non-mining operations, and plant operators. Most of the electricians and half of the carpenters who took part were also potentially exposed to silica over the OEL[15]. The best way to avoid health effects from exposure to any substance is to prevent exposure in the first place. Alberta Occupational Health and Safety (OHS) legislation requires

Downloaded by [Michigan State University] at 09:05 22 February 2015

employers to control workplace hazards using the hierarchy of controls which may also require the use of a combination of controls. Periodic health assessments are also important for early detection and prevention of silicosis and for determining if the control measures are effective. These are required by the Alberta OHS legislation for workers who may be exposed over the OEL for more than 30 work days in a 12-month period. Alberta OHS legislation also requires employers to develop and implement a code of practice if more than 10 kg of crystalline silica is present at the work site as a pure substance or in a mixture at a concentration more than 0.1% by weight where the aggregate amount is more than 10 kg[16]. In this paper, the data collected by Alberta JSTL on workplace controls during the crystalline silica exposure assessment project are summarized and analyzed. METHODOLOGY Data collected on workplace controls during the JSTL silica project formed the basis of this work. Exposure monitoring for airborne respirable silica at 40 work sites across 13 industry groups in Alberta between 2009 and 2013 was completed. Of these, 29 were fixed work sites; 11 were temporary (e.g. construction, drilling and servicing). The data analyzed in this paper were collected from visual observations during walkthrough inspections as well as observations and interviews conducted with employers and workers, while exposure to crystalline silica was

4

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT measured at the work site. The methodology for sample collection and analysis as well as the statistical treatment of the exposure data is described in Radnoff et al. (2014)[15].

The

consultant responsible for collecting the exposure measurements directly observed and documented work procedures and controls used during the full work shift over which exposure monitoring occurred. Both employers and workers provided information on work practices and

Downloaded by [Michigan State University] at 09:05 22 February 2015

controls present and used at the work site, including provision of training, use of protective equipment and availability of health surveillance. The types of controls for which data were collected were divided into ten categories, as summarized in Table I. Data in this paper were analyzed using SPSS version 22 (IBM Corporation, Armonk, New York, United States). For silica analysis, the laboratory quantitative detection limit was 0.010 mg. Treatment of results below the limit of detection was the same as previously reported[15]. Analyses were performed on log transformed data. P values for comparisons between groups were estimated using Student’s t-test on the log transformed data. RESULTS Overall, 343 occupational samples were collected from 287 workers and analyzed for respirable crystalline silica. At least one measurement exceeding the Alberta OEL for airborne respirable silica was found at 35 (88%) of the work sites evaluated; this occurred even when the geometric mean exposure at the work site was less than the 8-hour OEL. The information collected on exposure controls is summarized in Table II. Some companies used a combination of similar controls (for example ventilation on tools and on processes, enclosures and hoarding) or used a combination of similar work practices (for example, dry cleaning procedures and compressed air). Airborne dust or dust accumulations on surfaces were

5

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT observed at 21 (53%) of the work sites. In a few cases, there were sufficient data to evaluate the impact of a particular control, as described below. However, in most cases this was not possible because controls were either not used properly at all of the work sites evaluated in the industry group or the controls were not used consistently. None of the employers had historical exposure data for airborne respirable dust or crystalline silica that was collected prior to this study or prior

Downloaded by [Michigan State University] at 09:05 22 February 2015

to the installation of controls which could be used for comparison to the information collected. Substitution of non-silica abrasives in place of silica sand was used at four of the six abrasive blasting work sites. One company used garnet exclusively, one used slag products (nickel slag and vitreous smelter slag), one used ground glass and one used an aluminum oxide product in a blasting cabinet. The latter three companies also used silica sand products on occasion, although not at the time of the assessments. The geometric mean silica exposures at the abrasive blasting work sites where the non-silica abrasives were used were about 20% lower than at work sites where silica sand was used. Those work sites that had better separation of the blasting activities and better housekeeping appeared to have much lower rates of over-exposures (40 to 50% versus 80 to 90% of workers over-exposed). These results are discussed in more detail in Radnoff and Kutz, 2013[17]. Overall exposure data for foundry operations, by company, is summarized in Table III. One company (Company 2) had markedly better exposure results than the other three (no workers potentially exposure over the OEL). The companies were all involved in the casting of a variety of non-ferrous metals and so process operations were similar. However, a higher level of housekeeping (very clean environment, no visible airborne dust or smoke or dust

6

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT accumulations on surfaces observed) was noted at Company 2 compared to the other three work sites. At 16 (40%) of the work sites, heavy mobile equipment or vehicles with engineered ventilation systems were used. At half of these work sites, the vehicles were either driven with the windows open, or workers would wait outside the vehicle during loading activities. The

Downloaded by [Michigan State University] at 09:05 22 February 2015

exposure data for these workers is summarized in Table IV. There were 44 workers (51 samples) in this set; of these, 61% (27 workers) drove the vehicle for at least a portion of the work shift with the windows open. As expected, the GM respirable airborne silica exposure for these workers was higher than that for workers who kept the windows closed (0.017 mg/m3 versus 0.009 mg/m3), although this difference was not statistically significant (p=0.07). While more than a third of the companies used some form of enclosure or segregation, the systems were often compromised (in poor repair, tied back) or ignored by workers who would continue to access the area. Ventilation systems were observed at 18 (45%) of the work sites. These systems were not quantitatively evaluated; however visible disrepair, lack of maintenance, dust accumulations or visible airborne dust in the facility were noted at seven (39%) of these work sites. Housekeeping was limited or not effective at most of the work sites. This was likely because most companies used a combination of clean-up techniques. Almost two thirds of the companies used some form of dry clean up method, usually sweeping or shoveling. One third of the companies used compressed air for cleanup. Only 20% of the companies used wet cleaning methods, however dry cleaning methods and compressed air were also often used for clean-up at

7

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT the same companies. At three firms, compressed air was used to clean coveralls, even though this practice is prohibited under the Alberta OHS legislation. Worker decontamination procedures were also problematic. While 20 companies had shower facilities available, they were only used, by at least some workers, at seven (35%) of these work sites. Where separate lunch or break facilities had been provided, in most cases,

Downloaded by [Michigan State University] at 09:05 22 February 2015

workers used these facilities without first removing soiled protective clothing or other personal protective equipment (73% of the work sites). At nine of the work sites, there were no decontamination facilities at all, not even clean water to wash hands. A total of 23 (58%) of the companies reported providing health assessments to workers; the health assessment consisted of a pulmonary function test (PFT) at 22% of the companies. The remainder provided the health assessment (PFT, x-ray and health history) required by the Alberta OHS legislation. Only a quarter of work sites reported that they had implemented specific worker training for crystalline silica, even though the potential for exposure to crystalline silica was present at all of the companies assessed. Under the Alberta OHS legislation, the employer may take into account the protection provided by a respirator when determining whether a worker may be exposed above an OEL. Respiratory protective equipment (RPE) was available at 36 (90%) of the work sites and worn by at least some of the workers at 27 (75%) of these work sites. The respirable airborne crystalline silica exposure profile and the use of respirators by industry and worker occupation are summarized in Tables V and VI. Overall, 106 (37%) workers wore a respirator at the time of the assessment. Of these, 80% used a respirator which was correct for the type and level of measured airborne exposure to silica. However, 99 (34%)

8

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT workers did not use a respirator or the correct type of respirator to protect against the measured airborne exposure level. The types of respirators used varied somewhat, however a disposable half face air purifying respirator equipped with N95 or P100 filters (assigned protection factor or APF of 10) was used most often by workers participating in the assessments. The key exceptions were painters (half face or full face air purifying respirators equipped with organic

Downloaded by [Michigan State University] at 09:05 22 February 2015

vapour cartridges), abrasive blasters (supplied air blasting hoods with an APF of 1000 although some also wore N95 half face disposable respirators under the hoods) and concrete finishers who also used full face air purifying respirators equipped with P100 filters (APF of 10 or 100 depending on whether a qualitative or quantitative fit test was provided). Often, the workers observed wearing a respirator were not the workers who needed to wear one based on the measured level of exposure. Indeed, an inverse association was found between airborne exposure levels of silica; those in situations in which RPE was not being used having a higher GM exposure that those where it was being used (0.050 mg/m3 versus 0.018 mg/m3 respectively, pOEL2

0.020 0.005 0.014 0.11 0.020

1.68 2.27 2.09 2.63 4.18

25 -50 92 41

% Samples >NIOSH REL3 8 --83 25

2. The Alberta OEL is 0.025 mg/m3 3. The NIOSH REL is 0.05 mg/m3

27

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT TABLE IV: Respirable Crystalline Silica Exposure for Mobile Heavy Equipment and Vehicle Operators Window Position

Downloaded by [Michigan State University] at 09:05 22 February 2015

Open Closed Total

N1

No. Low Workers (mg/m3)

High Arithmetic Geometric (mg/m3) Mean Mean 3 (mg/m ) (mg/m3)

34 27 0.004 0.19 0.030 17 17 0.004 0.12 0.016 51 44 0.004 0.19 0.025 1. N number of samples (including duplicates)

0.017 0.009 0.014

GSD

% Samples >OEL2

2.79 2.48 2.81

35 18 29

% Samples >NIOSH REL3 21 6 16

2. The Alberta OEL is 0.025 mg/m3 3. The NIOSH REL is 0.05 mg/m3

28

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT TABLE V:Use of Respirators and Respirable Crystalline Silica Exposure by Industry

Downloaded by [Michigan State University] at 09:05 22 February 2015

Industry (No. work sites)

N1

Respirable Silica Exposure GM (mg/m3) 0.090

Workers with Exposure Above OEL2 (%) 12(92)

Exposed Above NIOSH REL3 (%) 12(85)

Used RPE (%)

Used Correc t RPE (%)

Sand and Mineral 13 8(62) 7(54) Processing (2) New Construction 34 0.055 28(82) 18(53) 14(41) 13(38) (4) Aggregate Mining 19 0.048 15(79) 10(58) 0(0) 0(0) and Crushing (3) Abrasive Blasting 30 0.038 20(67) 12(40) 20(67) 7(23) (5) Demolition (1) 8 0.027 4(50) 2(25) 4(50) 4(50) Oil and Gas (5) 24 0.024 10(42) 5(21) 8(33) 6(25) Foundry (4) 37 0.020 15(40) 10(27) 21(57) 19(51) Manufacturing (2) 19 0.020 9(47) 6(32) 9(47) 7 (37) Mining (5) 48 0.017 20(42) 8(13) 7(15) 7(15) Asphalt Plants (2) 11 0.016 4(36) 3(27) 3(27) 3(27) Earth Moving/ Road 18 0.013 5(33) 1(6) 0(0) 0(0) Building (3) Cement Plant (3) 21 0.010 3(14) 1(5) 12(57) 12(57) Limestone Quarry 5 0.007 0(0) 0 (0) 0(0) 0 (0) (1) Total 287 -145(51) 88(31) 106(37) 85(30) Note, a geometric mean (GM) was calculated for industry groups if there were six or more

Used No or Insufficien t RPE (%)4 5(38) 15(44) 15(79) 14(47) 2(25) 6(25) 5(14) 5(26) 20(42) 4(36) 6(33) 2(10) 0(0) 99(34)

exposure samples. 1. N number of workers (number of samples collected may be higher due to the collection of duplicate samples) 2. The Alberta OEL is 0.025 mg/m3 3. The NIOSH REL is 0.05 mg/m3 4. Airborne respirable crystalline silica concentration was above the OEL and the worker had no or insufficient protection based on the measured level

29

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT TABLE VI: Use of Respirators and Respirable Quartz Crystalline Silica Exposure by

Downloaded by [Michigan State University] at 09:05 22 February 2015

Occupation Respirabl e Silica Exposure GM (mg/m3)

Expose d Above OEL2 (%)

Exposed Above NIOSH REL3 (%)

Used RPE (%)

Used Correct RPE (%)

9 13

0.087 0.105

9(100) 12(92)

6(67) 11(85)

9(100) 9(70)

5(56) 8(62)

Used No or Insufficien t RPE (%)4 4(44) 4(31)

8 7

0.023 0.008

4(50) 1(14)

0(0) 1(14)

2(25) 1(14)

2(25) 1(14)

3(38) 0(0)

4 9

0.009

3(75) 1(11)

3(75) 1(11)

2(50) 1 (11)

2(50) 1(11)

1(25) 1(11)

10

0.038

7(70)

3(30)

0(0)

0(0)

7(70)

51

0.019

20(41)

13(25)

13(25)

11(22)

16(31)

5 23 5

0.016 0.011

3(60) 7(30) 1(20)

2(40) 4(17) 0(0)

0(0) 6(26) 4(80)

0(0) 5(22) 4(80)

3(60) 5(22) 1(20)

3

-

1(33)

0(0)

0(0)

0(0)

1(33)

81

0.032

52(64)

32(41)

39(48)

30(37)

31(38)

5 9 6 16 6 15 2

0.016 0.019 0.036 0.032 0.009 0.013 -

2(40) 4(44) 4(67) 9(56) 1(17) 3(20) 1(50)

1(20) 2(22) 2(33) 6(38) 0(0) 0(7) 1(50)

4(80) 1(11) 5(83) 4(25) 1(17) 5(33) 0(0)

4(80) 1(11) 2(33) 3(19) 1(17) 5(33) 0(0)

1(20) 3(67) 4(67) 9(56) 1(17) 3(20) 1(50)

Occupation

N1

Blaster Bricklayer & Concrete Cutting/Coring/Finish. Carpenter Dispatcher/Shipping Receiving/Admin. Electrician Equipment Operator (mining, above ground) Equipment Operator (mining, underground) Equipment Operator (non-mining) Lab. Analyst Foreman/Supervisor Labourer (mining, above ground) Labourer (mining, underground) Labourer (nonmining) Maintenance Mechanic/Technician Painter Plant Operator Professional Truck Driver Welder

30

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT Occupation

N1

Respirabl e Silica Exposure GM (mg/m3)

Expose d Above OEL2 (%)

Exposed Above NIOSH REL3 (%)

Used RPE (%)

Used Correct RPE (%)

Total 287 145(51) 88(31) 106(37) 85(30) Note, a geometric mean (GM) was calculated for worker groups if there were six or more

Used No or Insufficien t RPE (%)4 99(34)

Downloaded by [Michigan State University] at 09:05 22 February 2015

exposure samples. 1. N is the number of workers (number of samples collected may be higher due to the collection of duplicate samples) 2. The Alberta OEL is 0.025 mg/m3 3. The NIOSH REL is 0.05 mg/m3 4. Airborne respirable crystalline silica concentration was above the OEL and the worker had no or insufficient protection based on the measured level

31

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT

%Workers not using RPE

90

10 9 8 7 6 5 4 3 2 1 0

80 70 60 50 40 30 20 10

Downloaded by [Michigan State University] at 09:05 22 February 2015

0

% Workers not using RPE Maximum Crystalline Silica Exposure(mg/m3)

Industry (Maximum Crystalline Silica Exposure mg/m3)

FIGURE 1: Percentage of Workers Who Did Not Use Respirators, by Industry, and Potentially Over-Exposed to Respirable Crystalline Silica

32

ACCEPTED MANUSCRIPT

Exposure to crystalline silica at Alberta work sites: review of controls.

From 2009 to 2013, Alberta Jobs, Skills, Training, and Labour (JSTL) conducted a project to evaluate exposure to crystalline silica and assess control...
479KB Sizes 0 Downloads 5 Views