Occupational exposure assessment: Why you need an industrial hygienist

Transcription

1 Occupational exposure assessment: Why you need an industrial hygienist OEMAC Conference Montreal, September 29, 2013 Jan-Erik Deadman, PhD Corporate health and safety advisor Learning objectives Recognize the importance of assessing the right route of exposure Recognize the importance of correctly understanding the reference standard Be more critical of exposure assessments Recognize the central role of the industrial hygienist in the management of occupational health risks 2 Vice-présidence Ressources humaines, Hydro-Québec Plan Exposure assessment : Central to occupational health The process in detail Interactions with the occupational health team, managers and workers From perception to reality Proactive exposure assessment Reactive exposure assessment Conclusions 3 Vice-présidence Ressources humaines, Hydro-Québec 1

2 Exposure assessment "How important is this exposure?" "Does it represent a risk to health?" "Does it need to be reduced, and if so, how should it be done?" The answers to these questions are found in one of the most important functions performed by the industrial hygienist : exposure assessment. 4 Vice-présidence Ressources humaines, Hydro-Québec Exposure assessment : What is it? The process of estimating the magnitude of exposure to an agent and describing its sources, pathways and the uncertainties of the estimate Includes comparison with a reference value Two fundamental goals identify determinants of exposure (factors that modify exposures) identify risk to the health of exposed individuals Relies on observation, documentation and tools to evaluate a situation in the workplace Observation vision, hearing, olfaction & 6th sense Documents Ex., reference values, engineering plans / process flow charts material safety data sheets, published reports Tools Ex., equipment to measure concentration or level of exposure video camera, air velocity meter, smoke generator 5 Vice-présidence Ressources humaines, Hydro-Québec Exposure assessment : Central to occupational health Identify exposure to hazards Identify undesirable effects Risk management Exposure / risk assessment Risk control Identify tolerance levels (standards : legal, health, comfort, best practices) Evaluate exposure and risk Identify appropriate control measures Implement control measures Evaluate effectiveness 6 Vice-présidence Ressources humaines, Hydro-Québec 2

3 Exposure assessment : Central to occupational health Risk communication Education & training Exposure assessment Situation acceptable? - Legal standards - Health-based standards Yes - Comfort standards No (Negative exposure (Positive exposure determination) determination) Controls Engineering Administrative Work practice Personal protective equipment Epidemiological surveillance Medical surveillance Compliance monitoring 7 Vice-présidence Ressources humaines, Hydro-Québec Exposure assessment : The process What is the hygienist looking for? Opportunities for exposure Interactions between workers, raw materials, equipment and control measures that result in exposure to an agent at an undesirable level How does the hygienist do this? Understanding : Operations and tasks that constitute the processes Physical, chemical and mechanical principles at work Worker's habits Effectiveness of control measures Reference values (tolerance limits) Attentive observation of the work situation : People, equipment, organisation of activities 8 Vice-présidence Ressources humaines, Hydro-Québec Exposure assessment : The process Break down of activities into their basic steps Identification of raw materials, intermediates, final products, equipment, machinery and control measures used at each step: form, quantity, composition of materials intrinsic toxicity propensity to be released into the air relative importance of the quantity released Vice-présidence Ressources humaines, Hydro-Québec 3

4 Exposure assessment : Understanding the reference value Once exposure is adequately assessed, with what do we compare it? Is there a relevant reference value? For what (and whom) was it developed? : which health effects? chronic, acute, or sub-chronic? which reference population? which route(s) of exposure? What are the uncertainties? "nearly all workers" 10 Vice-présidence Ressources humaines, Hydro-Québec Interactions : It's teamwork! The industrial hygienist acts as the interface between the different occupational health experts : Safety officer / engineer Industrial hygiene technician Occupational physician / occupational health nurse Ergonomist Occupational psychologist between the different workplace experts : Worker (expert in work actually performed) Engineer / process designer (expert in work as designed) Manager (in between the above two ) and with external agencies : Analytical laboratory Consultants Regulatory agencies Media 11 Vice-présidence Ressources humaines, Hydro-Québec Exposure assessment : Interactions with OH professionals Epidemiological surveillance Medical surveillance The occupational hygienist's strong suit : identify, quantify, and propose solutions for exposures that present chronic risks Adequate exposure assessment allows better focussing of : medical surveillance epidemiological surveillance 12 Vice-présidence Ressources humaines, Hydro-Québec 4

5 Exposure assessment : Interactions with workers / management Adequate exposure assessment also allows risk communication and training to be geared to actual (and not hypothetical) exposure levels 13 Vice-présidence Ressources humaines, Hydro-Québec Exposure assessment : Interactions with management, engineering and workers Adequate exposure assessment also allows : Better tracking of exposure trends Better focussing of engineering, administrative or work practice controls Appropriate selection and use of PPE 14 Vice-présidence Ressources humaines, Hydro-Québec Exposure assessment : proactive and reactive Proactive (cause consequence) : Does a particular occupational situation present a risk to health? Reactive (consequence cause) : Can the observed or alleged health effects be related to an exposure in the workplace? 15 Vice-présidence Ressources humaines, Hydro-Québec 5

6 Exposure assessment from perception to reality risk perceived by the process designer risk perceived by the worker 16 Vice-présidence Ressources humaines, Hydro-Québec Exposure assessment from perception to reality Risk evaluation by an occupational hygiene professional Intrinsic toxicity x Route of exposure - Preventive = Risk measures Frequency 17 Vice-présidence Ressources humaines, Hydro-Québec Duration Comparison with tolerance level Exposure assessment from perception to reality Does this mean that we should disregard perception? Absolutely not! The goal is to align perceptions with objective risk assessment 18 Vice-présidence Ressources humaines, Hydro-Québec 6

7 Proactive exposure assessment Example : Prevention of health risks from exposure to lead Hydro-Québec's objective : establish best practices to manage lead exposure and prevent health risks Guide for preventing risks to health from lead exposure 19 Vice-présidence Ressources humaines, Hydro-Québec 1. Identify activity and the expected risk category 2. Identify corresponding preventive measures 3. Inform workers about the effects of lead on health and preventive measures 4. Implement preventive measures, including a respiratory protection program 5. Monitor the implementation of preventive measures in the field 6. If necessary, monitor concentration of lead in air and surface contamination 7. Institute biological monitoring if indicated. Proactive exposure assessment Example : Prevention of health risks from exposure to lead 20 Vice-présidence Ressources humaines, Hydro-Québec Proactive exposure assessment Example : Prevention of health risks from exposure to lead Low risk (< 50 ug/m 3 ) Moderate risk ( ug/m 3) High risk ( ug/m 3 ) Very high risk (> 2500 ug/m 3 ) 21 Vice-présidence Ressources humaines, Hydro-Québec 7

8 22 Vice-présidence Ressources humaines, Hydro-Québec Hydroelectric generating station built in MW 4 Francis turbines 15 employees Overhaul of generating units Anticorrosive leadbased paint used on many surfaces 23 Vice-présidence Ressources humaines, Hydro-Québec 24 Vice-présidence Ressources humaines, Hydro-Québec 8

9 Inside surface of spiral casing 25 Vice-présidence Ressources humaines, Hydro-Québec Lead identified on multiple surfaces by contractor Lead present in paint (0,2 % to 8,7 %) Hydro-Québec's objective : prevent health risks from lead exposure Contractor's objective : establish level of contamination before renovation work Wipe sampling conducted by contractor to determine presence and extent of any surface contamination Reference value used by contractor and industrial hygiene consultant 11 µg / 100 cm 2 Results for surfaces (values expressed in µg / 100 cm 2 ) 23 wipe samples < 11 µg / 100 cm 2 : 7 samples > 11 µg / 100 cm 2 : 16 samples (up to 3,030 µg / 100 cm 2 ) 26 Vice-présidence Ressources humaines, Hydro-Québec Misinterpretation of the surface sampling results Contractor concludes that exceedance of 11 µg / 100 cm 2 reference value represents a risk to workers' health Contractor informs our employees Workers' health and safety board (CSST) asked to inspect CSST inspector also equates the surface contamination with risk, citing the 11 µg / 100 cm 2 reference value All renovation work is stopped until surfaces are cleaned down to the reference value 27 Vice-présidence Ressources humaines, Hydro-Québec 9

10 Risk to health Our position Risk to health is assessed by evaluation of job tasks (airborne exposure monitoring, combined with blood lead testing if indicated) Surface wipe sampling is an indicator of the the presence (or absence) of lead, solely useful for evaluating the presence of lead and effectiveness of cleaning measures, cannot be used to predict health risk 28 Vice-présidence Ressources humaines, Hydro-Québec For what and for whom was the reference value developed? (2001) US : HUD / EPA value for decontamination of floors in residential environments Prevention of lead-related health effects in children 1 to 2 y old Assumes that lead paint is eaten or that contaminated objects are put into the mouth Assumes complete absorption of lead in the body Designed to limit blood lead in young children to < 10 µg/dl (2003) Canada : Department of National Defence (DND) adopts HUD / EPA guidelines for decontamination of shooting ranges (2006) Quebec : CSST recommends the DND values as a guideline for lead decontamination What does the literature say? No correlation between surface contamination and exposure, or risk to health 29 Vice-présidence Ressources humaines, Hydro-Québec Is there a relevant surface contamination standard for adults? Lange (2001) 108 µg /100cm 2 Highly conservative modeling of lead uptake in adults that assumes : 10 cm 2 of contact surface on hands 100% transfer from contacted surfaces to hands 100% transfer from hands to GI tract 35% absorption from the GI 30 Vice-présidence Ressources humaines, Hydro-Québec 10

11 Hydro-Québec's actions Cleaning / sealing of surfaces Heightened preventive measures (PPE, hygiene) Evaluation of exposure (airborne measurements & ingestion potential) Concentrations of lead in air Reference value (TLV) : 0,05 mg/m 3 (breathing zone) Results Fixed station monitoring : < mg/m 3 Personal measurements : 0.01 to 0.02 mg/m 3 Concentrations of lead in blood Reference value (TLV) : 0,5 µmol/l Results 9 workers : < 0.01 µmol/l 4 workers : 0.1 µmol/l 31 Vice-présidence Ressources humaines, Hydro-Québec Consequences of misinterpreting the results Worker anxiety, mistrust Management anxiety Unnecessary stoppage of work activities : costs Imposition of unnecessary protective measures : costs, inefficiencies Presumption of "contamination" in other generating stations Unnecessary legal, administrative procedures : costs Personal exposure monitoring, measurement of lead in blood : invasive 32 Vice-présidence Ressources humaines, Hydro-Québec Conclusions What does this case illustrate? Despite our best efforts at identifying, evaluating, controlling and communicating risk unforeseen events will trigger crises How "preventive" do we have to be? Perceptions matter hugely ; tracking them is key Root of the problem Inappropriate exposure assessment Solution to the problem Appropriate exposure assessment (industrial hygienist) Negative exposure determination as important as positive determination in correcting perceptions Effective communication (industrial hygienist) Aligning worker and management perceptions with reality Aligning regulatory agency approach with reality 33 Vice-présidence Ressources humaines, Hydro-Québec 11

12 Conclusions : The industrial hygienist A professional at the interface between people and their workplaces Plays a central role in minimising risk to health in the workplace Global view trained in anticipation, identification, evaluation, control and communication of risks interacts with other OHS professionals, management, workers, analytical laboratories, regulatory agencies, and more Objectivity diagnostic approach based on science and engineering Indirect benefits increased employee implication in OHS improvements in process design and efficiencies Future proofing workplaces will continue to expose workers to health hazards, and the risks will always need to be properly understood and managed 34 Vice-présidence Ressources humaines, Hydro-Québec Merci beaucoup! 35 Vice-présidence Ressources humaines, Hydro-Québec 12