Solvents are dangerous in more ways than one!

'All substances are poisons - the difference is in the dose'
Paracelsus (1521)

Acetone and other solvents (or Volatile Organic Solvents - VOC's) have come under increasing scrutiny and pressure is being applied by various governmental and private groups to find alternatives to their volatility and associated flammability and explosive properties, toxicity, potential for environmental damage, and cost to manage.

The Law

In particular The UK Health and Safety Executive (HSE) and all major insurance companies are keen to see VOC usage minimised. This is particularly important with the increase in personal claims for damages being brought by employees on their employers.

How Solvents Work

All solvents work by dissolving organic compounds thereby becoming increasingly contaminated and then require specialist treatment and disposal, costs for which are forecast to increase dramatically as the UK Government's Waste Strategy 2000 starts to affect the UK waste disposal industry.

Dangers to Humans

Solvents, and acetone more than most, are easily absorbed through the skin and also de-fat it. This often results in cracked, dry skin, eczema, dermatitis, allergies, and other skin conditions. Within minutes of exposure appreciable amounts of acetone are also found in the blood and from here may cause to damage to many key organs in the body. By crossing the blood-brain barrier it may also affect the central nervous system, causing behavioural disturbances both in the short and long term.

In addition solvents can act as carriers - dissolving chemicals that would otherwise remain outside the body and transporting them across the bodies defence membranes in the skin, mouth, nasal passages, etc.. These effects are often cumulative and therefore may have long-term implications on the health of workers and hence the potential for associated liabilities being incurred by employers.

The human body has developed the skin (epidermis) and other surface tissues of organs such as the lungs, mouth and nasal passages to act as a barrier to external compounds. However these tissues are by their very nature made of organic molecules - proteins, poly-saccharides, fats etc. This means that organic solvents naturally dissolve into these membranes and pass into the body proper. This in itself is a danger, but much more hazardous is the fact that these solvents dissolve and carry through the membranes other potentially toxic compounds that are on the skin and/or in the environment.

Alternative solvents to acetone tend to have higher flash points, meaning they are less flammable, but as a result do not evaporate from the tools that have been cleaned and leave behind greasy, oily residues which can contaminate further work, as well as being a hazard in themselves. They still have toxicity problems associated with all solvents in being easily absorbed through the skin and other membranes.

From an article by US Occupational Safety and Health Administration:
    Millions of workers are exposed to solvents on a daily basis. Health hazards associated with solvent exposure include toxicity to the nervous system, reproductive damage, liver and kidney damage, respiratory impairment, cancer, and dermatitis. Solvents share many chemical, physical, and biological properties that warrant national attention be directed to them as a group.
From a publication by the Centre for Disease Control in Atlanta, USA by J. Donald Millar, M.D., D.T.P.H. (Lond.), Assistant Surgeon General, Director, National Institute for Occupational Safety and Health, Centers for Disease Control.

Epidemiologic studies of various groups of solvent-exposed workers have demonstrated statistically significant chronic changes in peripheral nerve function (sensory and motor nerve conduction velocities and electromyographic abnormalities) that persisted for months to years following cessation of exposure. Epidemiologic studies have also shown statistically significant increases in neurobehavioral effects in workers chronically exposed to organic solvents.

These effects include disorders is characterized by reversible subjective symptoms (fatigability, irritability, and memory impairment), sustained changes in personality or mood (emotional instability and diminished impulse control and motivation), and impaired intellectual function (decreased concentration ability, memory, and learning ability). Among organic solvent abusers, the most severe disorders reported are characterized by irreversible deterioration in intellect and memory (dementia) accompanied by structural CNS damage.

From an article by Capt Mario E. Fajardo M.D., of the US Public Health Service
    Organic solvents are a distinct group of substances characterized by their ability to dissolve oils, fats, plastics, rubber and resins.

    Amongst those organic solvents commonly used, ketones are chemically stable substances, which include acetone, methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone. Exposure to high concentration of these agents can produce narcosis, headaches, nausea, vomiting, dizziness, loss of coordination, and loss of consciousness. At lower doses they can induce irritation of the eyes and respiratory passages and slow central nervous system activity. Respiratory failure and death have been reported with exposure to these agents.

    Most solvents irritate the mucous membranes of the eyes, nose and throat with the eyes being the most sensitive.

    The initial manifestation is typically a burning sensation, resulting from stimulation of the trigeminal nerve endings of the nose and eyes, although a cough may also be apparent as a result of stimulation of the laryngeal nerve endings in the throat. Aspiration of solvents into the lung can result in rapid and severe pulmonary damage. Heavy exposures are commonly manifested by cough, chest tightness and loss of breath.

    Organic solvents account for approximately 20% of occupationally induced dermatitis with this condition being most commonly localized to the hands. The hands are commonly affected while cleaning with solvents, by accidents, or by not using proper protective equipment. The main effect of solvents results from the dissolving of fats from the skin, which with repeated exposures will result in a red, dry, itchy skin. Consequently, as a result of the defatting action the permeability of the skin to other toxic substances is increased thus enhancing the potential for skin absorption. Repeated exposures can lead to the development of an irritant contact dermatitis, a condition that accounts for 90% of the reported occupational skin diseases.

    Prolonged exposure and absorption may even cause a chemical burn.

    Inhalation of organic solvents may cause a progression of symptoms from an initial euphoria to lethargy, dizziness, staggering gait, coma and death- not unlike symptoms associated with alcohol intake.
From a paper by Professor Bill Glass to the Head Injury Society of New Zealand:

Where solvent exposure is a continuing daily experience for the worker, symptoms may include:
  • end-of-week moodiness
  • carelessness about work quality
  • irritability
  • sleep and concentration difficulties
  • unpleasant smelling sweating at night in bed
  • solvent smell on breath, again more noticeable at night in bed.
Frequently, the patient will tell you his or her moods are 'fine'. The spouse will interrupt and says such things as, 'He's not the chap I married, Doc. He's dreadful to live with,' and so on. Almost inevitably you will also find that interpersonal relationships have deteriorated. In young men their girl friends are always 'ditching' them, and in married couples, separation is frequent. Aggressive behaviour is also often a feature at home and at work, with verbal and physical abuse in the family a real possibility.
Thus, the effects of this workplace hazard are transferred to the home, often with disastrous consequences.
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