Fibre monitoring at a Pilbara based iron ore mine site. 5th December 2017

Transcription

1 Fibre monitoring at a Pilbara based iron ore mine site Teresa Smith 5th December 2017

2 Overview Introduction Asbestos and its health impacts WA mining regulation Methodology Results Conclusion Recommendations

3 Introduction Naturally occurring fibrous minerals are managed in accordance with Department of Mines and Petroleum (DMP) guideline. Potential to encounter fibrous minerals throughout exploration and mining activities. The geology is well understood in the Pilbara region and at this particular iron ore mining operation. The site selected for this project has a documented Fibrous Minerals Management Plan which details: classification of pit locations based on potential for fibrous mineral occurrence a range of appropriate controls, from engineering to the use of respiratory protection 3

4 Introduction A monitoring program for airborne fibres was implemented between Aug 2016 and Jan 2017 commenced operating in a designated area Designated area s are not classified based on the likelihood of airborne fibres exceeding the OEL There was an expectation for personal and area monitoring daily Three SEG s were targeted for monitoring in this project 1. Heavy mobile equipment (HME) operators 2. Drill operators (blast hole drilling) 3. Blast crew members A review of the personal exposure data was undertaken to inform a risk based program and appropriate controls. 4

5 Asbestos and its health impacts Asbestos is a silicate mineral fibre found naturally Two primary classes are serpentine and amphibole Amphibole fibres: are rigid, durable and needle-like (morphology) considered potent carcinogens (e.g. crocidolite) can accumulate in lungs which can impact on health Dose-response relationship Can cause pleural plaques, asbestosis and malignant tumours like mesothelioma The Australian occupational exposure limit (OEL) for all asbestos fibres is 0.1f/mL (NOHSC, 1995) There is no safe threshold level for exposure to carcinogens 5

6 WA mining regulation Iron ore mining operations may experience amphibole minerals as a result of the banded iron formations present in the geology of the region Managing this hazard includes identification of fibrous minerals management of contaminated material documented work procedures risk based air monitoring to verify controls are effective Risk based hygiene management programme 6

7 Methodology 1. Similar Exposure Group (SEG) determination 2. Preliminary risk assessment 3. Planned sampling for Fibre sampling methodology AirChek52 sampling pumps Calibrated to ~1.5L/min (+/- 10%) Asbestos cowl, pre-loaded by NATA lab Membrane filter method (NOHSC 2005) DMP s definition: any object with an aspect ratio > 3:1, length >5µm and width <1µm. SEM for selected samples Table 1: Similar Exposure Groups SEG No. Activity Description of tasks SEG 1 SEG 2 SEG 3 Heavy Mobile Equipment (HME) operator (closed cabin) Drill operator (closed cabin) Blast crew Table 2: Risk based sample plan 2017 Operating heavy mobile equipment including load and haul, waste removal, pit road maintenance. Avg headcount Average hours per week Blast hole drill operator Staff involved in blasting operations (staking, priming, AN facility, clearing shots) SEG No. Activity Agent Minimum sample size SEG 1 HME operation Fibres 6 SEG 2 Drill operator (closed cabin) Fibres 10 SEG 3 Blast crew Fibres 6 7

8 Methodology 5. OEL 0.1f/mL for 8 hr day, 40 hr avg week 6. Adjustment for extended shifts AIOH WES Adjustment tool shows Asbestos as a cumulative toxicant adjusted TWA OEL from 0.1 f/ml down to 0.07 f/ml (adjusted OEL). 7. Statistical analysis using IHStat 95th percent upper confidence limit (UCL95) 8. Awareness presentations delivered by independent COH The risk of developing asbestos related disease from low levels of exposure Exposure monitoring program objectives Summary of exposure results Ongoing risk based sample programme 8

9 Results Table 3: Summary of SEG 1, SEG 2 and SEG 3 exposure results (current and 2016 combined) from IHSTAT analysis of fibre results Displayed as % of the adjusted exposure standard Number of samples Mean as a percent of the adjusted OEL Geometric Standard Deviation (GSD) Current OEL (TWA, 8 hr) Reduction factor Adjusted OEL (TWA, 12 hr) Distribution fit (LogNormal, Normal, Both, Neither) UCL 95 as a percent of the adjusted OEL MVUE as a percent of the adjusted OEL Percent of samples above the adjusted OEL (%) SEG SEG 1 HME Operators f/ml f/ml Lognormal SEG 2 Drill Operators f/ml f/ml Lognormal SEG 3 Blast crew f/ml f/ml Both (Normal, W- test=0.845)

10 Results 2 results were > analytical method limit of reporting Sample 5: 25/100 SEM showed 4 fibres asbestiform Sample 6: 91/100 SEM showed 2 fibres asbestiform Majority of fibres present were inorganic such as clay and iron oxide Figure 1: Percentage of samples collected in relation to a percent of the adjusted OEL Figure 3: Sequential data plot from IHSTAT analysis of SEG 2 94% of samples were equal to or less than the analytical method limit of reporting Figure 2: Number of samples based on length of rosters for SEG 1, SEG 2 and SEG 3 combined Figure 4: Number of samples by reported concentration for SEG 1, SEG 2 and SEG 3 combined 10

11 Discussion Sample analysis was conducted using IHSTAT for three operational exposure groups. SEG 1 (n = 14) and SEG 3 (n = 7) results were all below 25% of the adjusted OEL indicating exposures are controlled. SEG 2 (drill operators) had a large GSD (GSD >3). Potentially due to dust and presence of organic and inorganic fibres. SEG 2 also had the highest UCL95 (UCL95 = 35% of the adjusted OEL). Despite potential outliers, some conclusions are: majority of samples have a low sample concentration (mean is less than 10% of the adjusted OEL) further investigation would be recommended to clarify cause of higher results. Exposure data reviewed indicates that atmospheric exposure to fibres is currently controlled. As a result of the current low exposures, a risk based sampling program shall be implemented throughout

12 Discussion An awareness training presentation was developed to communicate changes in the monitoring programme. There are benefits when engaging a 3 rd party to deliver presentations: SME in fibre exposure monitoring and analysis Independence Potential disadvantages could be: Perception that the company has reduced ownership Perception that workers are unlikely to ask questions Considered to be credible Ability to manage potential emotive responses Technical support for leaders and site HS team

13 Conclusion Fibre monitoring results for HME operators, Drill operators and Blast crew were analysed using IHSTAT. There was sufficient data to complete analysis using IHSTAT Due to 2 potential outliers in SEG 2 the sample plan for 2017 will target 10 additional fibre samples to investigate contributing factors for these higher results. Exposure results indicate that atmospheric exposure to fibres are currently controlled and therefore a risk based sampling plan is reasonable and aligns with regulatory guidelines and internal standards. 13 May 2017

14 Recommendations SEG 2 analysis & investigate contributing factors to sample 5 & 6 Continue to align site procedures with the DMP s guideline Whilst active work is undertaken in designated areas undertake an annual awareness campaign Fibre awareness training should be kept up to date with recent data Ensure workers are clean shaven & fit tested (AS/NZS 1715:2009) 14

15 Thankyou and any Questions? 15