asecos Main catalogue - Working safely with hazardous substances

348 Which limit values are relevant for activities involving hazardous materials? When working with hazardous substances, employees must be protected from substance-related hazards and damages. For the assessment of health hazards when handling and storing hazardous substances, the following limit values must be observed: ››› Limit values according to REACH DNEL: Derived No-Effect Level (derived exposure level without effect) (by manufacturers or importers/marketers) DMEL: Derived Minimum Effect Level Risk-based limit values for carcinogenic and germ cell mutagenic substances (not provided for in REACH, only in legally nonbinding ECHA guidelines) ››› Limit values according to the Ordinance on Hazardous Substances/TRGS 900 OEL: Occupational exposure limit vs. MWC: Maximum workplace concentration ››› Carcinogenic hazardous substances according to TRGS 910 ERB: Exposure-Risk Relationships vs. TGC: Technical Guideline Concentration ››› HSE workplace exposure limits according to EH40/2005 WEL‘s: Workplace exposure limits Are British occupational exposure limits which are set in order to help protect the health of workers. WEL’s are concentrations of hazardous substances in the air, averaged over a specified period of time, referred to as a time-weighted average (TWA). Two time periods are generally used: ››› long-term (8 hours) and ››› short-term (15 minutes) ››› The short-term exposure limits (STEL’s) are set to help prevent effects such as eye irritation, which may occur following an exposure for a few minutes. Extraction of hazardous materials The concentration ratios between odour threshold value, occupational exposure limit value, short-term value and lower explosion limit are illustrated in the following figure: A possible health hazard can also be derived from the odour threshold value. Unpleasant or even annoying odours should always be the first sign of a possible health risk when working with hazardous substances. For the evaluation of possible explosion hazards during activities with flammable hazardous substances, the lower explosion limit (LEL) must also be taken into account. The occupational exposure limit value (OEL) as a legally binding threshold value The occupational exposure limit value (OEL) is the limit value for the time-weighted average concentration of a substance in the air at the workplace in relation to a given reference period. It specifies the concentration of a substance at which acute or chronic harmful effects on health are generally not to be expected. Occupational exposure limit values are shift averages for approx. 8 hours daily exposure five days a week during the working life. Ethyl acetate Ethanol Toluene Xylene Heptane 800 ppm 800 ppm Short-term value 200 ppm 200 ppm 2.000 ppm 400 ppm 200 ppm Occupational exposure limit 50 ppm 100 ppm 500 ppm from << 1 ppm ~from 10 ppm Odour threshold value 0,15 ppm < 1 ppm ~250 ppm Lower explosion limit (LEL) 2,1 Vol-% = 21.000 ppm 3,1 Vol-% = 31.000 ppm ~1,0 Vol-% = 10.000 ppm Please observe local legislation and regulations.

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