250 likes | 583 Views
Biological monitoring MSc in Occupational Hygiene. Finlay Dick Department of Environmental & Occupational Medicine University of Aberdeen. Some definitions. Biological monitoring (BM) - the measurement of a substance or its metabolite in a biological medium such as blood, urine or breath
E N D
Biological monitoringMSc in Occupational Hygiene Finlay Dick Department of Environmental & Occupational Medicine University of Aberdeen
Some definitions • Biological monitoring (BM) - the measurement of a substance or its metabolite in a biological medium such as blood, urine or breath • Biological effect monitoring (BEM) - the measurement of pre-clinical effects in exposed workers
Exposure, absorption and effects* Ambient monitoring Exposure Internal dose Adverse effects Biological monitoring Biological effect monitoring *Adapted from Cassarett & Doull’s Toxicology 5th Edition, ed. Klassen CD pp995. McGraw Hill, 1995
Objectives • Evaluate control measures • Detect earlyadverse effects • Assess immunity (biological agents)
When is biological monitoring appropriate? significant exposure is likely andthere is a likelihood of adverse effects
What can be measured? • The substance - Trichloroethylene • A metabolite - Urinary TCA • An adverse effect - liver enzymes
The ideal test • Valid technique - reliable - reproducible • Sensitive and specific • Acceptable to workers • Safe, easy to perform • Non-invasive
Ethical issues • Informed consent of employees - what is proposed - what are the risks - what are the consequences - who gets to see results • Discussion with Trades unions
Practical considerations • Is the metabolite unique to that agent? • Are there possible confounders- alcohol - diet - age • What to sample - blood - urine - breath
Sampling time* Half-life < 2 hours ~ 2-10 hours ~ 10 - 100 hours > 100 hours Optimum sampling time Elimination too rapid to measure Post- shift or before next shift End of shift, end of week Random (timing not critical)
Practical considerations 2 • How much to sample • Special containers - metal free tubes - preservatives • Storage - refrigerate? • Quality control - laboratory QA schemes
Interpreting results - population versus ‘benchmarking’ • Biological exposure indices (BEI) - ACGIH • Biological monitoring guidance values (BMGV) - HSE - Health Guidance value (HGV) - Benchmark Guidance Value (BGV) • Lead monitoring - HSE - action level - suspension level • Biological Tolerance Values (BAT) - DFG
Feedback of results • Employees - individual and group • HSE - certain agents e.g. lead - individual and group • Employers - anonymised, group data • Safety committee - group data • Trades Unions - group data
Audit and review • Are results satisfactory • Is control satisfactory • Are the trends downwards • Can we do better
Useful texts • “Biological monitoring in the workplace” (HSG 167) HSE Books • Industrial Chemical Exposure - Guidelines for Biological Monitoring 3rd Edition. RR Lauwerys, P Hoet. CRC Press 2001 • “Guidance on Laboratory techniques in Occupational Medicine” 8th Edition Health & Safety Laboratory 1999