Extending the Validity of Sampling for Mercury at Low Levels by Modifying NIOSH Method 6009, Cold Vapor Atomic Absorption

Transcription

1 Extending the Validity of Sampling for Mercury at Low Levels by Modifying NIOSH Method 6009, Cold Vapor Atomic Absorption Vince Daliessio, CIH, Industrial Hygiene Project Manager Scott Van Etten, National Director of Industrial Hygiene EMSL Analytical, Westmont NJ

2 The Problem Recently mercury-contaminated buildings have been recycled for residential use, without proper assessment or remediation NIOSH 6009 cannot see Mercury to appropriate clearance levels unmodified

3 What Is Elemental Mercury?

4 Unique Properties Symbol Hg (hydrargyrum) Has a significant vapor pressure ( mm Hg) Equilibrium concentration at STP approximately 18mg/m3

5 Implications Density-flows to inaccessible areas Liquid absorbed into porous building materials Amalgamates with other metals Re-vaporizes slowly over time to cause significant air concentrations

6 Why Is Mercury Bad? Particularly toxic to developing brain, nervous system, respiratory system, kidneys, teeth, gums, skin

7 Some Mercury Products

8 Manometers

9 Thermometers

10 Thermostats

11 Barometers

12 Gas Meters

13 Mercury - Vapor Lamps

14 Fluorescent Lamps

15 Materials Resilient flooring Paints Dental Amalgam

16 Published Air Limits OSHA - PEL- 100 ug/m3 ACGIH - TLV- 25 ug/m3 ATSDR -(Cleanup)- 0.5 ug/m3 EPA - Rfc ug/m3 ATSDR-MRL-0.1 ug/m3

17 Air Sampling by NIOSH 6009 Particulates, vapor, both MCEF (part.) Carulite (vapor) 0.2 Liters per minute for 100 minutes Current RL by CV-AAS is 0.05 ug (0.5ug/m3 at 100L)

18 But the method falls short! Air volume to hit the ACGIH Cleanup Level (0.5ug/m3); 0.05ug/0.0005mg/m3 = 100L Air volume to hit the EPA Reference Concentration (RfC ug/m3); 0.05ug/0.0003mg/m3 = 166L Air volume to see the ACGIH Minimal Risk Level (MRL - 0.1ug/m3); 0.05ug/0.0001mg/m3 = 500L

19 Possible alternatives Rathje and Marcero(1976) - higher sorbent volume, higher flowrates and volumes than NIOSH 6009 Regulatory agencies often require agency methods EPA Method Gold-coated media, cost is significant ICP-MS promises much lower detection limits Newer technology, methods are lacking, cost

20 Near-term solution Validate NIOSH 6009 for higher volumes Spike tubes in the concentration range of interest Draw multiples of the method volume through the tubes Compare mass recoveries and reported concentrations Use these to support sampling at 2x-5x method volume

21 Spiking Tubes Spiked with different volumes of saturated aerosol solution (18 mg/m3); 3000 ul = ug 5000 ul = ug 8000 ul = ug

22 Aerosol Spiking Solution Vial, 25 ml, ~ 5g of Hg

23 Tube Spiking Apparatus

24 Sample Tubes, T w/septum, Trap

25 Drawing Up Aerosol Spike

26 Injecting Aerosol Spike

27 Collecting Sample Air Volume

28 Results Spike masses reported were higher than expected Lab temperature was higher than STP; 28C vs 25C Corrected spike masses were in good agreement Selected 8000ul spike (0.26ug Hg) for sample volume study

29 Spiking Study - Theoretical vs. Reported Mass Mass ug Theoretical Mass Reported Mass Report Limit Spike Volume ul

30 Results - 1X method volume Good agreement with spiking study Consistent recovery across multiple samples ug Consistent air concentrations ug/m3

31 1X Method Volume Reported Mass Reported Mass ug HG0009 HG0009A HG0010 HG0010A HG0011 HG0011A HG0012 HG0012A HG0013 HG0013A Report Limit

32 1X Method Volume Reported Air Concentration 2.50 Air Concentration ug/m HG0009 HG0009A HG0010 HG0010A HG0011 HG0011A HG0012 HG0012A HG0013 HG0013A Report Limit 0.00

33 Results - 2X method volume Fair agreement with spiking study Somewhat consistent recovery across multiple samples ug Somewhat consistent air concentrations ug/m3 2 samples less than 200L

34 2X Method Volume Reported Mass Reported Mass ug HG0014 HG0014A HG0015 HG0015A HG0016 HG0016A HG0017 HG0017A HG0018 HG0018A Report Limit

35 2X Method Volume Reported Air Concentration Air Concentration ug/m HG0014 HG0014A HG0015 HG0015A HG0016 HG0016A HG0017 HG0017A HG0018 HG0018A Report Limit

36 Results - 3X method volume Good agreement with spiking study Very consistent recovery across multiple samples ug Very consistent air concentrations ug/m3

37 3X Method Volume Reported Mass Reported Mass ug HG0004 HG0004A HG0005 HG0005A HG0006 HG0006A HG0007 HG0007A HG0008 HG0008A Report Limit

38 3X Method Volume Reported Air Concentration Air Concentration ug/m HG0004 HG0004A HG0005 HG0005A HG0006 HG0006A HG0007 HG0007A HG0008 HG0008A Report Limit

39 Discussion Method appears to work for volumes up to 300L Significant limitations include extended sampling time, battery life More samples required before a valid statistical analysis can be done May be acceptable to regulators requiring an agency method

40 Helpful Links ATSDR Toxicological Profile - Mercury; NIOSH Method 6009; OSHA Safety and Health Topic - Mercury;

41 Contact Info Phone x vdaliessio@emsl.com