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Gossman Consulting, Inc

HWF NOTES© 


Gossman Consulting, Inc.                                                                                                                                           February, 1993

Nearly all hazardous waste fuel facilities now use gas chromatography for quality control. Most are performing PCB determinations and many are also performing pesticide and/or gross volatile/semivolatile constituent determinations. GCI has pursued an aggressive policy of assisting our clients in moving away from the more toxic and hazardous solvents used in GC work such as n-hexane and carbon disulfide. During recent discussions with Tom Murphy, Manager of Environmental, Health and Safety Services for Ash Grove Cement, he mentioned an article he had written a few years ago on the health and safety aspects of GC solvents. With his kind permission, we reprint it here. It seems particularly pertinent for many HWF laboratories. Please feel free to copy and pass this issue among your laboratory personnel.

GC SOLVENTS - SAFETY AND HEALTH

Tom Murphy CIH

Analytical chemists tend to develop areas of specialization and, frequently, there are special safety and health concerns not discussed in instrument and methods manuals, e.g.: AA and ICP daily use may result in dangerous exposure to metal fume if suitable fume hoods are not used. Gas chromatography also has certain built-in hazards to practitioners, unless appropriate safeguards are taken.

For some laboratories actively engaged in GC work, rapid growth can mean crowded work spaces, inadequate or inappropriate storage facilities for stock and waste solvents, poor or non-existent fume hoods and, often, work loads that may invite safety short-cuts as expedient; unsafe work habits may gradually gain acceptance.

The fire and explosion hazards of solvents used in GC should be well understood by all laboratory workers who use them. However, the biological hazards may be less obvious. Since many solvents exert their toxic effects through all routes of exposure - by inhalation, ingestion and dermal routes - a limited number of Biological Exposure Indices (BEIs) have been established by the American Conference of Governmental Industrial Hygienists (ACGIH). BEIs are reference values for the chemical in question or its metabolite, or even a marker of biochemical change induced by the chemical. Often, the measurement of BEI is made on urine, blood or exhaled air.

Review of the ACGIH BEIs listed for 1987-88 show many solvents commonly used by GC workers: n-hexane, toluene, carbon disulfide and (still) benzene among them. (Methyl alcohol is currently under study.) The following table* is presented to raise safety and health consciousness of GC workers:

SOME BIOLOGICAL EXPOSURE INDICES

Indices Determinant BEI Sample
Benzene Total Phenol 50 mg/L urine-end of shift
n-Hexane

(and methyl n-butyl ketone)

2,5-Hexanedione

or n-Hexane

5 mg/L

40ppm

urine

end-exhaled air during shift

Carbon Disulfide 2-Thiothiazolidine-Carboxylic Acid(TTCA) 5 mg/g creat urine-end of shift
Toluene Hippuric Acid 2.5 g/g creat urine

There are many qualifiers for applications of BEIs, e.g.: what are normal backgrounds, lifestyle and general metabolic state of the worker? More to the point, most BEIs were developed from experience with plant or process workers, e.g.: viscose rayon workers and carbon disulfide. Chemists and other laboratory workers tend not to be monitored for these exposures. Moreover, many laboratory workers have the freedom to presume great risks upon themselves, possibly out of familiarity.

The health hazards presented by certain solvents are well known, having been well documented by the press: toluene and glue-sniffers CNS depression, methanol and optic nerve damage, and benzene and pernicious anemia - leukemia.

Less well known for their health effects are n-hexane and carbon disulfide, two of the most widely used of all GC solvents. Documentation for the current TLV**-TWA for n-hexane shows that this solvent can cause a polyneuropathy to workers exposed to concentrations below 500 ppm.

Carbon disulfide, commonly used to desorb industrial hygiene air samples from activated charcoal, has been assigned a TLV-TWA*** of 10 ppm. Toxicity has been characterized by wide-ranging CNS disturbances; chronic exposure has been held responsible for cardiovascular disease.

Methylene chloride, another common GC solvent, is not yet on the BEI list, but is known for its metabolite, carbon monoxide. Dermal protection from methylene chloride is a challenge because most glove materials are attacked; PVA gloves, however, are resistant, but must be protected from water.

Finally, toxicologists have shown that multiple exposures to various solvents can create additive, synergistic, or potentiating effects, e.g.: methyl ethyl ketone potentiates methyl n-butyl ketone; i.e.: toxic effects of M-nBK are much worse when combined with MEK exposure. Many solvents are simply additive in their effects.

It is expected that chemists and other laboratory workers, because of greater depth of knowledge gained through specialized training, will have a greater understanding of the hazards presented by chemicals. OSHA has recognized this in its approach to regulating laboratories; chemists are stewards of their own on-the-job safety and health to a much greater extent than the average worker.

Consistent with this is our obligation and responsibility to gain in-depth knowledge of all chemicals we use, as well as the safety measures needed to limit exposures to them.

* Threshold limit values and Biological Exposure Indices for 1987-88 - American Conference of Governmental Industrial Hygienists, pp. 53-63.

** Threshold Limit Values

*** Threshold Limit Value - Time Weighted Average

Editor's Note: The American Conference of Governmental Industrial Hygienists has recently issued additional BEIs for methanol, MEK and perchloroethylene as well as a notice of intent to establish BEIs for acetone and MIBK. In addition, the ACGIH '92 TLV for n-hexane is 50 ppm.