Pub Health 4310 Health Hazards in Industry

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Pub Health 4310Health Hazards in Industry

• Dave Wallace
• Lecture 4
• Organic Solvents

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ORGANIC SOLVENTS

• Objectives
• This session is intended to be an informative
  overview of the organic solvents and their
  toxicological effects.
• Students should be able to
• Know the general characteristics of solvents and
  solvent exposure
• Be familiar with specific effects of selected
  solvents

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ORGANIC SOLVENTS

• Introduction
• Nearly everyone is exposed to organic solvents.
  Since the degree of exposure (dose) varies
  greatly, the toxic effects also vary. However,
  the toxicity of solvents depends to a great deal
  upon the chemical nature of the compound.

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ORGANIC SOLVENTS

• General principles
• Solvents tend to be volatile liquids, so workers
  are usually exposed to vapors.
• Vapor concentration can be expressed as ppm or
  mg/m3, according to the following relationships

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ORGANIC SOLVENTS

• General principles
• Solvent exposure affected by airborne
  concentration, solubility, and exposure
  frequency.
• Higher vapor concentrations for enclosed spaces
  with poor ventilation, and with solvents having a
  high vapor pressure.
• When inhaled, lipid-soluble solvents will easily
  enter the blood
• Solvents also can pass through the skin, although
  not usually a significant route of exposure.
• Solvents often de-fat or irritate the skin.

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ORGANIC SOLVENTS

• General principles
• Toxic effects of solvents include
• depression of the central nervous system, and
• irritation of membranes and tissues.
• CNS depression tends to increase as the length
  of the carbon chain increases.
• Molecules with more than 5 carbons generally are
  not volatile enough to cause hazardous exposures.
  
• CNS-depressant properties are increased with the
  addition of halogens and alcoholic functional
  groups
• alkanes ltalkenes ltalcohols ltorganic acids ltesters
  ltethers lthalogenated compounds

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ORGANIC SOLVENTS

• General principles
• All organic chemicals can cause tissue
  irritation.
• Solvents can extract lipids from cell membranes,
  casing irritation and cell damage.
• As the molecular size increases, the potential
  for irritation increases
• In general, irritation increases with the
  addition of functional groups
• Unsaturated compounds are stronger irritants than
  their saturated counterparts
• alkanes ltalcohols lt aldehydes or ketones ltorganic
  acids ltamines

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ORGANIC SOLVENTS
CnH2n2

• Saturated aliphatic solvents
• Alkanes are the least acutely toxic of the
  solvents.
• Mildly irritating vapors
• Weak anesthetic properties
• Heavier compounds have more CNS depression and
  irritation.
• N-hexane, CH3CH2CH2CH2CH2CH3, is an exception
• Widely used industrial solvent until it was found
  to have neurotoxic properties.
• Chronic exposure causes peripheral neuropathy,
  affecting the hands and feet
• heptane also has similar effects

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ORGANIC SOLVENTS
CnH2n

• Unsaturated aliphatic solvents
• Alkenes are toxicologically similar to the
  alkanes
• Greater irritant and anesthetic properties
• No neurotoxic properties

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ORGANIC SOLVENTS
Benzene

• Aromatic hydrocarbons
• Aromatic hydrocarbons include at least one
  benzene ring.
• Aromatics are far more irritating than aliphatics
• Dermatitis and skin de-fatting
• Skin, eye, and lung damage.

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ORGANIC SOLVENTS
Benzene

• Aromatic hydrocarbons
• Benzene has been used for many industrial
  purposes, component of gasoline
• High exposure levels can cause death by CNS
  depression or cardiac arrhythmias
• Skin exposure causes dermatitis
• Inhalation of high concentrations may result in
  bronchial irritation or pulmonary edema.

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ORGANIC SOLVENTS
Benzene

• Aromatic hydrocarbons
• Benzene (Cont.)
• Chronic exposure causes blood disorders of
  aplastic anemia and leukemia.
• Victims of chronic benzene poisoning usually have
  a red blood cell count that is only 50 of
  normal.

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ORGANIC SOLVENTS

• Aromatic hydrocarbons
• Alkyl benzenes include toluene, xylenes, etc.
• More powerful narcotic effect than benzene
• Not known to cause blood disorders

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ORGANIC SOLVENTS
Anthracene

• Polycyclic aromatic hydrocarbons,(PAH)
• Products of combustion.
• Also known as polynuclear aromatics (PNA)
• Carcinogenic potential
• Sir Percival Pott identified the link between
  soot exposure and scrotal cancer among chimney
  sweeps.
• More recently, cancer among coke oven workers,
  coal gasification workers is attributed to PAH
  exposure.

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ORGANIC SOLVENTS

• Halogenated hydrocarbons
• These compounds are good solvents, with low
  flammability.
• CNS-depressant qualities make them good aesthetic
  agents for surgery.
• Can cause cardiac arrhythmias and liver and
  kidney damage.

Perchloroethylene
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ORGANIC SOLVENTS

• Halogenated hydrocarbons
• Carbon tetrachloride, CCl4
• Strong CNS depressant
• Potent liver toxin
• Acute exposure can cause death
• Chronic exposure can cause cirrhosis
• Chloroform, CHCl3
• CNS depressant
• High exposure levels can cause liver and kidney
  damage and cardiac arrhythmias.

Carbon tetrachloride
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Old carbon tetrachloride fire extinguishers
Hand grenades
Installed systems
Pump extinguisher
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ORGANIC SOLVENTS

• Halogenated hydrocarbons
• Methvlene chloride, CH2Cl2
• Not as toxic as the other chlorinated methanes
• A suspected carcinogen
• An excellent solvent
• Widely used in industry
• The 1997 OSHA methylene chloride standard should
  result in a reduction in the use of this
  chemical.

Methylene chloride
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ORGANIC SOLVENTS

• Halogenated hydrocarbons
• Vinyl chloride , CH2CHCl
• Skin irritant with CNS depressant properties
• Much industrial hygiene concern over this
  chemical is due to its carcinogenic potential
• Chronic exposure may result in liver cancer
  (angiosarcoma) and other cancers as well.

Vinyl chloride
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ORGANIC SOLVENTS

• Alcohols
• The alcohols are CNS depressants and irritants.
• Alcohols seldom are serious workplace hazards due
  to their irritating effects. The irritant
  properties decrease and systemic toxicity
  increases as the size of the molecule increases.

Ethanol
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ORGANIC SOLVENTS

• Alcohols
• Methanol, CH3OH (wood alcohol, methyl alcohol)
• Common industrial solvent
• Methanol poisoning may result in blindness, other
  neurological damage, or death.
• Methanol poisoning 8 - 36 hrs after ingestion
• Caused by compounds produced by methanol
  metabolism
• Inhibited by administering ethanol

Methanol
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ORGANIC SOLVENTS

• Alcohols
• Ethanol, CH3CH2OH (ethyl alcohol, grain alcohol)
• Irritant and a depressant
• The toxicology of this compound is well know
  through centuries of voluntary ingestion
• It does not have the neurotoxic properties of
  methanol

Ethanol
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ORGANIC SOLVENTS

• Glycols
• Glycols have less oral toxicity than monohydroxy
  alcohols and they also are less irritating
• Ethylene Glycol (antifreeze)
• Acutely toxic when ingested due to oxalic acid, a
  metabolite which causes kidney damage.
• Glvcol ethers are reproductive toxins
• Use in the semiconductor fabrication industry has
  been an issue of concern.

Ethylene glycol
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ORGANIC SOLVENTS

• Aldehydes
• Aldehydes are strongly irritating to mucous
  membranes
• Can cause CNS depression, but their irritating
  nature usually prevents significant exposure.
• Formaldehyde is regulated by OSHA as a
  carcinogen.
• Can cause sensitization in about 4 - 8 of the
  population.
• Glutaraldehyde
• Commonly used in hospitals to sterilize
  endoscopes and other equipment
• Also causes sensitization.

Formaldehyde
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ORGANIC SOLVENTS

• Ketones
• CNS depressants
• Irritating effects cause workers to avoid high
  exposures
• Toxic properties of ketones generally increase
  with increasing molecular weight.
• Acetone, (2-propanone) is a relatively safe
  solvent, as its principle toxic effect is
  irritation.

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ORGANIC SOLVENTS

• Ethers
• Anesthetic effect of ethers increases with the
  size of the molecule
• Very flammable, and they can be easily oxidized
  to explosive peroxides.
• Ethyl ether, CH3CH2OCH2CH3 (diethyl ether)
• Had been widely used as an anesthetic

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ORGANIC SOLVENTS

• Phenols
• Phenols are extremely irritating, capable of
  causing severe burns from direct contact.
• Phenol is cytotoxic to all cells and tissues, and
  is toxic by all routes of exposure
• Rapidly absorbed through the skin
• Fatalities have resulted within 10 minutes of
  skin exposure.