TOXIC HAZARDS FROM SOLVENT EXPOSURE IN METAL PLATING INDUSTRIES

Daniel J. McCoy, Ph.U. Blodgett Regional Poison Center

1840 Wealthy SE Grand Rapids, Michigan 49506

Numerous chemicals have been used for their solvent proper- ties. The variety of chemicals used in industrial as well as academic and research applications have included a number of different chemical families. Technically, water should be included as a solvent, however, when the term is typically used it designates several groups of organic compounds.

The types of solvents addressed in this review include mineral spirits and the chlorinated hydrocarbons. In order to proper- ly evaluate the health hazards presented by these chemicals it is necessary to review the chemical properties, the potential routes of exposure, the relative toxicity, and the acute and chronic effects of exposure to each of these chemicals.

The first of these chemicals, mineral spirits, is known by a number of different names. Benzine, petroleum spirits, miner- al turpentine, naphtha and painters naphtha are just a few of the synonyms of mineral spirits. This solvent is actually a mixture of a number of different hydrocarbons. It is dis- tilled from petroleum and is composed of chemicals having generally five to seven carbons. It represents the fraction of crude oil which has a boiling point range from 20 to 60 de grees centigrade. Mineral spirits is generally a volatile, clear, colorless and non-fluorescent liquid. Depending on the specific constituents, the specific gravity ranges from 0.6 to 0.9 grams;milliliter. This solvent is flammable (explosive limits in air between 1 and 6 % ) and presents a dangerous fire risk.

Exposure to mineral spirits can be by the oral route, by inhalation or by dermal exposure. Although, ingestion would probably not occur in an industrial setting, it is possible that an accident may happen. The oral toxicity is general mild, possibly causing a burning sensation, vomiting and diarrhea. some mild drowsiness is possible. Aspiration of mineral spirits into the lungs following vomiting Usually does not cause severe symptomatology, but on occasion has resulted in a chemical pneumonia. The more common industrial exposures typically would involve skin contact or inhalation of the vapors. In these instances mineral spirits would cause moder- ate irritation to the skin, eyes and the mucous membranes. Although not frequently encountered, inhalation of concentrat- ed vapors may cause intoxication similar to alcohol accompa- nied by headache, nausea, and possibly coma. Some of these symptoms may be due to relative anoxia.

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The chlorinated hydrocarbons probably represent the most commonly encountered solvents. This discussion will be limit- ed to the shorter chained chemicals including the chlorinate methanes, ethanes and ethenes. The chemical properties of these particular chemicals are somewhat similar to one anoth- er. All virtually are clear, colorless liquids which have distinctive odors. Many have an odor similar to chloroform while others have more of an ethereal odor. These solvents are generally heavier (greater specific gravity) than water, with the exception of chloroethane and chloroethene (vinyl chloride) which are slightly less dense than water. All are volatile materials which present a number of possible routes of exposure. These can be divided into several types includ- ing accidental or intentional ingestion; workplace exposure to the skin or by inhalation; and environmental such as through the drinking water or from accidental spills. The type of exposure that presents the most severe acute intoxication is often overlooked. The intentional use by the "buffers", llbaggersll or "sniffers" for the euphoric effects, has been shown to result in significant damage to health. Industries which utilize these types of solvents should constantly be aware .of the potential for this misuse.

Acute oral exposure from any of these solvents can result in nausea, vomiting, diarrhea, and transient damage to the liver and the kidneys. Gentral nervous symptoms can occur following ingestion, however, these are not usua.11~ as severe as the others. Skin exposure can range from mild to fairly severe. Typical changes observed are reddening and blistering of the skin. This is often accompanied by or caused by the "solvent" properties of these agents, the ability to dissolve lipids. This is known as the "defatting" of the skin.

The most serious effects associated with these chemicals are due to the effects of inhalation, partlcularly when exposure occurs over a long period of time. The symptoms associated with acute exposure are nausea, vomiting, dizziness, headache and fatigue. In high enough exposures, a number of these agents can act as sn anesthetic, leading to unconsciousness and coma.

Dichloromethane, chloroform and carbon tetrachloride are the chlorinated- methanes. A s the TLV's listed in table 1 show, the relative toxicity of this series increases as the number of chlorines increases. The toxic action of these three chemicals are somewhat disrinct. Uichloromethane, also known as methylene chloride, is metabolized by the body to form carbon monoxide. Together, the methylene chloride and the carbon monoxide deprive the tissues of adequate oxygen supply, resulting in abnormal function of the liver, kidney and the

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central nervous system. Chloroform and carbon tetrachloride exert similar toxic effects. Both form intermediate metabo- lites which bind to essential proteins in the tissues, dis- rupting normal function. The result of significant exposure to these two chemicals can-be severe liver and kidney damage.

The chlorinated ethanes are very commonly used solvents. The seven compounds in this group are shown in table 2 . These contain from one to four chlorines and as indicated by their TLV's as listed in table 3 , as with the methane series, the more chlorines, the greater the toxicity. l,l,l-trichloroeth- ane is one of the solvents that has been used as a drug of abuse. It is common for such abuse to result in unconscious- ness, seizures, respiratory arrest, cardiovascular abnormali- ties and even sudden death. Although work exposure is not usually as acutely severe, these same type of symptoms can occur. In general, the toxic mechanism for this group varies depending on the different metabolic pathway followed. Over- all, as with the chlorinated methanes, the typical toxic effects involve the liver, kidney and the central nervous system. One common effect of these chemicals which is common for all the chlorinated hydrocarbons, is the sensitization of the heart to epinepherine (adrenaline). Death has occurred in individuals involved in very strenuous activity following exposure to these solvents, especially after abuse by sniff- ing.

Table 4 gives the name and structure of the chlorinated ethenes. Although similar in structure to the ethanes, the presence of the double chemical bond between the two carbons causes some significant differences. A s a group, as shown by the TLV's in table 5, these are more toxic than the ethanes. Another difference in this series is that the rule that more chlorines makes more toxic does not hold. As the TLV's indi- cate, 1,l-dichloroethene with two chlorines and vinyl chloride with one chlorine are both more toxic than the ethenes with three or four chlorines. The general toxic mechanisms and effzects for these compounds are for the most part similar to the methanes and ethanes. The target organs are the liver, kidpAey 2nd cextral m e n v r n 9 - e A L G A V . J U J c . 1 7 e ,,atem.

The type of symptoms resulting from exposure as discussed above have been primarily those of an acute nature. There are, however, toxic effects which are caused by chronic expo- sure to these agents. chronic toxic effects include all the changes that have been described following acute exposure. In addition to these, however, chronic exposure can result in mutagenic, teratogenic or carcinogenic effects. A mutagen is a chemical or physical agent which cause changes in genetic material. Teratogens are agents which cause changes in the developing embryo. A carcinogen causes cancer. At least four

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of the chlorinated solvents (Table 6) have been shown to have mutagenic effects in animals. No fewer than nine (Table 7) have been demonstrated as causing cancer in animals and at least one, chloroform, is a teratogen in animals. Vinyl chloride is a proven mutagen in humans as well as a carcino- gen. Both carbon tetrachloride and 1,2-dichloroethane are also proven to be human carcinogens.

Prevention of exposure to these solvents is the optimal way to reduce the risk of toxicity. Protective clothing including solvent resistant gloves and goggles are important safety steps in this endeavor. Adequate workplace ventilation is critical in reducing exposure via inhalation. Some situations necessitate masks with filters or self contained breathing apparatus as a precaution. Air monitoring should be an inte- gral part of the occupational safety program when these sol- vents are used in significant quantities.

Should accidental exposure occur, there are several basic treatment measures that should be taken. The first involves termination of the exposure by removing the individual from the site and removal of contaminated clothing. It is very important that the "rescuer" be adequately protected, to prevent himself from also suffering the same fate. Symptomat- ic and supportive care should be given. If necessary support- ed ventilation should be initiated. Further care may involve plasma expanders and additional support of the cardiovascular system. Liver and kidney function should be monitored as well as the electrolyte status of the blood. In the majority of the acute exposures, recovery is complete in several days to a few weeks. The more significant risk from these agents are those that are the result of chronic exposure which may result in damage which is not detected until it is too late.

Common sense, monitoring and prevention of exposure are the keys to the safe utilization of this important and useful group of chemicals.

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selected References

Barlow, S.M., & Sullivan, F.M., REPRODUCTIVE HAZARDS OF INDUS- TRIAL CHEMICALS, Academic Press, New Your, N.Y., 1982.

Baselt, Randall C., DISPOSITION OF TOXIC DRUGS AND CHEMICALS IN MAN, 2ND Ed., Biomedical Publications, Davis Cal,. 1982.

Doull, John (et al), TOXICOLOGY - THE BASIC SCIENCE OF POI- S O N S , 2nd Ed., Macmillan Pub. Co. Inc., New, N.Y., 1980.

DRINKING WATER AND HEATLH, National Academy Press, Washington D.C., Vol. 1 (1977), Vol. 2 (1980), Vol. 3 (198O), Vol. 4 (19821, Vol. 5 (1983), Vol. 6 (1986), & Vol. 7 (1987).

Finkel, Asher J., HAMILTON AND HARDY'S INDUSTRIAL TOXICOLOGY, 4th Ed., John Wright - PSG Inc., Boston, Mass., 1983. Lauwerys, Robert R., INDUSTRIAL CHEMICAL EXPOSURE: GUIDELINES FOR BIOLOGICAL MONITORING, Biomediocal Pukblications, Davis, Cal., 1983.

THE MERCK INDEX, 9th Ed., Merck 7 Co., Inc., Rahway, N.J., 1976.

Proctor, Nick H., & Hughes, James, P., CHEMICAL HAZARDS OF THE WORKPLACE, J.B. Lippincott Co., Phildelphia, Penn., 1978.

Sax, N. Irving, DANGEROUS PROPERTIES OF INDUSTRIAL MATERIALS, 6th Ed., Van Nostrand Reinhold Co., New York, N.Y., 1984.

Schardein, James L., CHEMICALLY INDUCED BIRTH DEFECTS, Marcel Dekker, Inc., New York, N.Y. , 1985.

Schwarz, Richard H., & Yaffe, Sumner J., DRUGS AND CHEMICAL RISKS TO THE FETUS AND NEWBORN, Alan R. Liss, Inc., New York, N.Y., 1980.

Swanson, Margo, & Cook, Raymond, DRUGS, CHEMICALS AND BLOOD

EXPOSURE TO SPECIFIC DRUGS AND CHEMICALS, Drug Intelligence Publications, Hamilton, Ill., 1977.

DYSCRASIAS - A SUMMARY OF BLOOD ABNORMALITIES ASSOCIATED WITH

TOXNET, National Librarky of Medicine, Washington, D.C., 1987.

Verschueren, Karel, HANDVOOK OF ENVIRONMENTAL DATA ON ORGANIC CHEMICALS, Van Nostrand Reinhold Co., New York, N.Y., 1977.

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TABLE 1

CHLORINATED METHANES

TLV

dichloromethane 100 ppm

chloroform 10 PPm

carbon' tetrachloride 5 PPm

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TABLE 2

H H

CHLORINATED ETHANES

C 1 H I 1 I I

I 1 I I

C1-C-C-H I I

H- C- C- C 1 I I

H H

c1-c-c-c1 I !

I 1 I I

H H H H H H

CHLORO- 1.1-DICHLORO- 1.2-DICHLORO- ETHANE ETHANE ETHANE

C 1 H I I

C1-C-C-H I I I I

C 1 H

1 1.1-TRI- CHLOROEHANE

c1 c1 I !

c1-c-c-c1 H H I 1 I I

1 . 1 . 2 . 2 - T E T R A - CIILOROETIIANE

c1 c1 C1-C-C-H

I 1 I I

I I I I

H H

1 . 1 . 2 - T R I CHLOROETHANE

C 1 H ! I

c1-c-c-c1 C 1 H

I 1 I 1

1 . 1 , l 1 2 - T E T R A - CIILOROETHANE

TABLE 3

CHLORINATED ETHANES

TLV

chloroethane 1000 ppm

1,l-dichloroethane 1120 ppm

1,2-dichloroethane 35u ppm

l,l,l-trichloroethane 5w ppm

1,1,2-trichloroethane 10 PPm

1,1,2,2-tetrachloroethane 5 ppm

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TABLE 4

CHLORINATED ETHENES

H H I, I

C1-C=C-H

I VINYL CHLORIDE

C 1 H I I I I

C1-C=C-H

1 . 1 - D I - CHLORO- ETHENE

c1 I I

H-C=C-H I I

c1 trans- 1 . 2 - DICHLORO-

ETHENE

c1 c1 ! I

C1-C=C-H

TRICHLORO ETHENE

c1 c1 I !

H-C=C-H

cis- 1.2- DICHLORO-

ETHENE

c1 c1 ! I

C l - C = C - C l

TETRACHLORO ETHENE

TABLE 5

CHLORINATED ETHENES

TLV

cis-1,2-dichloroethene 200 ppm

trans-l,2-dichloroethene 200 ppm

trichloroethene 5 0 PPm

tetrachloroethene 50 PPm

1,l-dichloroethene 10 PPm

vinyl chloride 1 PPm

TABLE G

ANIMAL MUTAGENS

dichloromethane

1,l-dichloroethene

tetrachloroethene

TABLE 7

ANIMAL CARCINOGENS

chloroform

carbon tetrachloride

1,X-dichloroethane

1,1,2-trichloroethane

vinyl chloride

1,l-dichloroethene

trichloroethene

tetrachloroethene ,

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