extending the validity of sampling for mercury at low levels by modifying niosh method ... ·...

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

Atomic AbsorptionVince Daliessio, CIH, Industrial

Hygiene Project ManagerScott Van Etten, National Director of

Industrial HygieneEMSL Analytical, Westmont NJ

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

What Is Elemental Mercury?

Unique Properties

• Symbol Hg (hydrargyrum)• Has a significant vapor pressure

(0.0012 mm Hg)• Equilibrium concentration at STP

approximately 18mg/m3

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

Why Is Mercury Bad?• Particularly toxic to developing brain,

nervous system, respiratory system, kidneys, teeth, gums, skin

Some Mercury Products

Manometers

Thermometers

Thermostats

Barometers

Gas Meters

Mercury - Vapor Lamps

Fluorescent Lamps

Materials

• Resilient flooring• Paints• Dental Amalgam

Published Air Limits

• OSHA - PEL- 100 ug/m3• ACGIH - TLV- 25 ug/m3• ATSDR -(Cleanup)- 0.5 ug/m3• EPA - Rfc - 0.3 ug/m3• ATSDR - MRL - 0.1 ug/m3

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)

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 - 0.3 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

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

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

Spiking Tubes

• Spiked with different volumes of saturated aerosol solution (18 mg/m3);– 3000 ul = 0.0540 ug– 5000 ul = 0.0900 ug– 8000 ul = 0.1440 ug

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

Tube Spiking Apparatus

Sample Tubes, ‘T’ w/Septum, Trap

Drawing Up Aerosol Spike

Injecting Aerosol Spike

Collecting Sample Air Volume

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

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

0.3000M

ass

ug

3000 3000 5000 5000 8000 8000 ReportLimit

Spike Volume ul

Spiking Study - Theoretical vs. Reported Mass

Theoretical MassReported Mass

Results - 1X method volume

• Good agreement with spiking study• Consistent recovery across multiple

samples– 0.17-0.23 ug

• Consistent air concentrations– 1.69 - 2.35 ug/m3

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

Rep

orte

d M

ass

ug1X Method Volume Reported Mass

HG0009HG0009AHG0010HG0010AHG0011HG0011AHG0012HG0012AHG0013HG0013AReport Limit

0.00

0.50

1.00

1.50

2.00

2.50

Air

Con

cent

ratio

n ug

/m3

1X Method Volume Reported Air Concentration



• Fair agreement with spiking study• Somewhat consistent recovery across

multiple samples– 0.15-0.22 ug

• Somewhat consistent air concentrations– 0.69 - 1.67 ug/m3– 2 samples less than 200L

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

Rep

orte

d M

ass



0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

Air

Con

cent

ratio

n ug

/m3




• Good agreement with spiking study• Very consistent recovery across multiple

samples– 0.22-0.25 ug

• Very consistent air concentrations– 0.72 - 0.83 ug/m3

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

Rep

orte

d M

ass



0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

Air

Con

cent

ratio

n ug

/m3



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

Helpful Links• ATSDR Toxicological Profile - Mercury;

http://www.atsdr.cdc.gov/toxprofiles/tp46.html

• NIOSH Method 6009;http://www.cdc.gov/niosh/nmam/pdfs/6009.pdf

• OSHA Safety and Health Topic - Mercury;http://www.osha.gov/dts/chemicalsampling/data/CH_250510.html

Contact Info

• Phone - 856-858-4800 x 1240• email - [email protected]

extending the validity of sampling for mercury at low levels by modifying niosh method ... ·...

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