Exposure to Crystalline Silica at Alberta Work Sites. Occupational and Environmental Medical Association of Canada September 29, 2014

Transcription

1 Exposure to Crystalline Silica at Alberta Work Sites Occupational and Environmental Medical Association of Canada September 29, 2014

2 Outline Silica Project Overview Alberta Occupational Exposure Limit for Silica Occupational Disease from Silica Exposure in Alberta Occupational Exposure to Silica Next Steps

3 Silica Project

4 Silica Project Began April 2010 Objective: gather information to address challenges related to crystalline silica exposure in Alberta workplaces Participants: Alberta Jobs, Skills, Training and Labour Workers Compensation Board Alberta Health Alberta Health Services Various stakeholder associations

5 Project Objectives Gather information on where and how workers are exposed and ranges of exposure Identification of occupational disease rates in Alberta due to silica exposure Evaluation of technical feasibility of OEL and OEL adjustment method Improved level of understanding on compliance with legislation

6 Occupational Exposure Limit

7 Occupational Exposure Limit (OEL) for Crystalline Silica OELs are airborne concentrations of substances to which it is believed that most workers can be exposed without suffering adverse health effects The current Alberta OEL for crystalline silica (silica) is mg/m 3 Value is based on the 2006 ACGIH TLV High risk for development of silicosis and lung cancer at the former OEL levels of 0.1 mg/m 3 (quartz) and 0.05 mg/m 3 (cristabolite)

8 Occupational Exposure Limit (OEL) for Crystalline Silica OELs should not be considered fine lines between safe and unsafe conditions Even at mg/m 3 there is still an excess risk for silicosis in occupational settings over a working lifetime (>1/1000)* *National Institute of Occupational Safety and Health, Health Effects of Occupational Exposure to Respirable Crystalline Silica, (2002) Park et al. Exposure to Crystalline Silica, Silicosis, and Lung Disease Other than Cancer in Diatomaceous Earth Industry Workers: A Quantitative Risk Assessment, Occup. Envir. Med. 59(1): (2002)

9 Size Selective OELs Inhalable (100 µm cut-point), hazardous when deposited anywhere in the respiratory tract Thoracic (10 µm cut-point), hazardous when deposited in the lungs Respirable (4 µm cut-point), hazardous when deposited in the gas exchange regions of the lungs The silica OEL is based on respirable particulate

10 Adjustment of OELs OELs are intended for exposures of 8 hours/day, 40 hours/week For work shifts longer than 8 hours, OELs must be adjusted What does this mean? The OHS Code requires the use of the Brief and Scala* formula (Section 18) For a 12 hour work shift, the OEL for silica is reduced to mg/m 3 *Brief R.S., Scala R.A. Occupational Health Aspects of Unusual Work Schedules: A Review of Exxon s Experiences, Am Ind Hyg Assoc J., 47(4): (1986)

11 Is Adjustment Necessary? A weekly adjustment, such as the Quebec model, should be used rather than a daily adjustment when the Quebec model* is applied, there is typically little or no adjustment Where the biological half-life is less than three hours or more than 400 hours, adjustments to the OEL may not be necessary* *IRSST, Guide for the Adjustment of Permissible Exposure Values (PEVs) for Unusual Work Schedules, Technical Guide T-22, 200 Verma, Dave, Adjustment of Occupational Exposure Limits for Unusual Work Schedules, AIHAJ, 61: (2000)

12 OEL Adjustment for Silica Recommendation that the OHS Code be amended: A notation 4 (do not adjust) should be added to the substances interaction column in Table 2, Schedule 1 for crystalline silica The department will, by policy, allow employers to follow this recommendation when assessing workplace exposure to silica until the legislation is amended

13 Occupational Disease from Silica Exposure

14 Cost of Occupational Disease A recent study* identified that the number of fatal and non-fatal occupational illnesses in the United States was estimated at more than 53,000 and nearly 427,000, respectively For fatal illnesses, 1.8% were pneumoconiosis, 34% were COPD Medical costs for injuries and illnesses estimated at $67 billion Indirect costs (lost earnings, fringe benefits, home production) estimated at almost $183 billion By comparison, costs for cancer estimated at $219 billion; cost for coronary disease estimated at $152 billion *Leigh, J.P. Economic Burden of Occupational Injury and Illness in the United States, The Millbank Quarterly, Vol 89, No 4, pp (2011)

15 Occupational Disease Reporting It is important to have accurate reporting for occupational disease Ensures that impact of over-exposures are properly understood by stakeholders Helps identify industries and occupations at risk Ensures that the costs are attributed correctly Typically, in jurisdictions with good reporting systems, about 40% of occupational disease cases are submitted to the worker compensation system How do we perform in Alberta?

16 Occupational Disease Rates in Alberta In the same 10-year period: Alberta Jobs, Skills, Training and Labour 2 cases of silicosis were reported to the Director of Medical Services WCB WCB accepted 29 claims for probable/confirmed silicosis Alberta Health Over 850 cases of silicosis reported from emergency, hospital or physician claims data (based on diagnosis coding)

17 Does Alberta Have an Occupational Disease Issue? If we look at employer data, the answer is no If we look at JSTL data, the answer is no If we look at WCB data, the answer is there is some occupational disease from silica exposure in certain high-risk occupations (e.g. abrasive blasting) Do we really know if this is an issue given the inconsistencies in reporting?

18 Occupational Disease Reporting What do we need for better reporting? Employers must be aware of and comply with the legislative requirements Employers/workers must have an awareness of the hazards in their occupation Medical professionals must recognize and diagnose the condition Worker or medical professional must file a claim/report

19 Elements for Occupational Disease Surveillance What do we need? Standardized way to evaluate worker health Worker made aware of the outcome of the assessment Follow-up done with the worker Results reported to work site (with consent) Physician provides feedback on the effectiveness of controls Employer provides feedback to workers on results Employer reviews controls/systems in place to protect workers Do we have all the elements needed?

20 BUT Occupational disease rates are not a good indicator for how well we are doing now!

21 Silica Exposure in Alberta

22 Exposure Assessments 2009/2010 Coal Mining 2010/2011 Construction Asphalt and cement plants Sand and gravel operations New commercial construction 2011/2012 Construction and Abrasive Blasting Sand and mineral processing Demolition New commercial construction Road building Abrasive blasting 2012/2013 Manufacturing and Oil and Gas General manufacturing Foundries Well-site servicing operations Bulk plants 2014 Residential Construction

23 Description of Exposure Assessment Studies Detailed collection of field data: Environmental conditions Number of workers and worker tasks Observation of work activities during the measurement period Full-shift breathing zone measurements for airborne respirable crystalline silica and total respirable dust Use of controls documented

24 Occupational Sampling Results, Overall 377 samples collected (315 workers) 180 samples above 8-hour OEL of mg/m 3 (48%) 105 samples above NIOSH REL of 0.05 mg/m 3 (28%) Total of 48 work sites evaluated (29 fixed, 19 temporary)

25 Occupational Exposure, by Industry Industry (# work sites) N Low (mg/m 3 ) High (mg/m 3 ) GM (mg/m 3 ) %Above %Above 0.05 Sand and Mineral Processing (2) Commercial Construction (4) Sand and Gravel (3) 22 ND Abrasive Blasting (5) Demolition (1) Oil and Gas (5) 28 ND Foundry (4) 44 ND Residential Construction (8) 34 ND Manufacturing (2) 23 ND Mining (5) 50 ND Asphalt Plant (2) 13 ND Earth Moving/Road Building (3) 24 ND Cement Plant (3) 26 ND Limestone Quarry (1) 6 ND

26 Occupations with Potentially High Exposures Occupation N Low (mg/m 3 ) High (mg/m 3 ) GM (mg/m 3 ) % above Concrete Cutting, Coring, Finishing Blaster (Abrasive Blasting) Electrician Equipment Operator (mining, underground) 10 ND QC/Lab. Technician Labourer (non-mining) 106 ND Plant Operator 21 ND Painter Maintenance Carpenter Mechanic/Technician 11 ND Drywaller 18 ND

27 Variability of Exposure within Industry Groups Company N Low (mg/m 3 ) High (mg/m 3 ) GM (mg/m 3 ) % Above Manufacturing (other) 1 11 ND Oil and Gas 1* ND ND Mining 1 13 ND ND ND

28 Variability of Exposure in Construction Industry (# work sites) N Low (mg/m 3 ) High (mg/m 3 ) GM (mg/m 3 ) %Above %Above 0.05 Commercial Construction (4) 44 ND Demolition (1) Residential Construction (8) Earth Moving/Road Building (3) 34 ND ND Overall 112 ND

29 Impact of Drywall Results on Silica Exposures in Residential Construction Industry (# work sites) N Low (mg/m 3 ) High (mg/m 3 ) GM (mg/m 3 ) %Above %Above 0.05 Residential Construction w/o Drywalling Drywalling only 18 ND 0.23* Overall 34 ND Note: for respirable dust exposures mean about 10 times higher for drywallers compared to other workers *Result is uncertain as it was below detection limit

30 Exposure in Abrasive Blasting Abrasive Product Used N Low (mg/m 3 ) High (mg/m 3 ) GM (mg/m 3 ) %Above Ground Glass* Garnet Silica Sand Silica Sand Nickel slag, Vitreous Smelter Slag Overall *Blasters were cleaning concrete.

31 Silica Content of Non-Silica Abrasives Product Quartz Content (w/w%) MSDS Disclosure of Quartz/Crystalline Silica (%w/w) Ground Glass* Not disclosed Aluminum Oxide 0.09 crystalline particles: no Garnet1* 0.76 <0.5 Nickel Slag* 0.30 no crystalline silica Vitreous Smelter Slag* 0.28 <0.1 Staurelite Garnet Not disclosed, but silicosis noted as a chronic health effect Garnet <0.5% Coal Slag (silica as metal silicates) Glass Beads 0.23 Not disclosed

32 Controls: Common Themes Build-up of visible dust on surfaces even where ventilation systems were in place Enclosures and barrier systems often ineffective (incomplete, tied back, damaged or ignored) Lack of facilities for basic hygiene Use of inappropriate work procedures (e.g. dry cleaning methods) Lack of worker training Inadequate decontamination (facilities not used even if available)

33 Controls: Common Themes Personal protective equipment Respirators not properly cleaned and stored Clothing and other equipment not decontaminated Workers needing respirators not always using it

34 Key Findings Worker exposure was highly affected by work activity and potential for incidental exposure Elevated exposure to silica was found in occupations where it was not anticipated In many cases, the companies evaluated had controls in place but they were not always used or used properly Work procedures may have a large impact on workplace exposures Lack of awareness of the hazard likely contributed to issues with work practices 34

35 Food for Thought Occupational disease reporting processes need to be improved; must ensure that all of the parties who have responsibility are involved When considering worker exposure, attention must be paid to the activity the worker will be doing (not just occupation) and their potential for incidental exposure Hazard awareness is still poor 35

36 Food for Thought There is a lot of focus on engineering controls and their efficacy Engineering controls are only as good as the people who use and maintain them Administrative controls such as work practices, housekeeping and training can have a large impact on exposures Cost-benefit?

37 Questions? 37