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THE SOLVENT CONNECTION
NIOSH (USA) stated in 1987 in their Current Intelligence Bulletin that aldehydes are solvents: “Common organic solvents are classified as aliphatic hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, ketones, amines, alcohols, aldehydes, and ethers”.
In correspondence with New Zealand’s Accident Compensation Corporation (ACC) Professor Gorman, Health Science Centre, University of Auckland, accepts that glutaraldehyde is a solvent under Axelson and Hogstedt’s definition. Dr Monigatti (ACC Workwise, NZ) states: “We accept glutaraldehyde has solvent-like properties. If chronic solvent exposure can cause these sorts of things then we accept that glutaraldehyde can cause [solvent toxicity] as well....(Safeguard Update, No 96, 20 April, 1998).
NIOSH (1987) states: “ 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 electromyographicabnormalities) that persisted for months to years following cessation of exposure. Epidemiologic studies have also shown statistically significant increases in neurobehavioural effects in workers chronically exposed to organic solvents. These effects include disorders characterised by reversible subjective symptoms (fatigability, irritability, and memory impairment), sustained changes in personality or mind (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 characterised by irreversible deterioration in intellect and memory... accompanied by structural CNS damage.”
Two international workshops have categorised solvent-induced CNS disorders (NIOSH p 17):
“Type 1 is characterised by fatigue, memory impairment, irritability, difficulty in concentrating, and mild mood disturbance. Type 2A includes sustained personality or mood changes and Type 2B impairment in intellectual function manifested by diminished concentration, memory and learning capacity. The boundaries are not necessarily clearcut.”
Other labels: Organic Brain Syndrome, OBS / Psycho-Organic Syndrome, POS /
Solvent-Induced Chronic Toxic Encephalopathy, CTE.
The diagnosis is usually based on case histories, symptoms and psychometric tests. Work in Sweden has shown that long-term solvent-exposed workers have disturbances of the equilibrium (vision/sense of balance) system and that an otoneurological test battery (ear nerves/balance) adds worthwhile information about abnormalities within the brainstem-cerebellar complex.  It is the same VIII nerve which carries messages about sound and balance.
A second report showed that the long-term solvent exposed were worse at recognising distorted speech and had significantly longer cortical response audiometry, ie the time taken for the message to reach the brain stem. There was no difference between the control group and the solvent group in recognising pure tones or single syllable speech. The findings suggest long-term solvent exposure causes disturbances of the central pathways in the otovestibular complex (hearing and balance nerves and their connections).
Another Swedish study indicates that a 5 year follow-up of workers shows effects on the central nervous system persist after exposure ceases, with reduced activity, leisure, education and training, and more neuropsychiatric symptoms. They did not get worse. If a worker was removed when he had symptoms without signs of intellectual impairment, recovery was seen in most cases. See also the sections on Glutaldehyde/Formaldehyde Neurotoxicity and Rehabilitation pp 23-29.
Dr Keir Howard states: “It is worth remembering that many organic solvents are related to anaesthetic gases and have the same effects. Solvents form the base of many paints, laquers, varnishes, thinners, waxes, printing inks and adhesives and are used for degreasing and cleaning purposes as well as forming the base of many therapeutic and pesticide mixtures... It is always worth being reminded that the commonest organic solvent to which people are exposed is ethyl alcohol in the form of beer, wines and spirits... the effects are essentially identical to over-exposure to the various organic solvents used in the industry... consumption of alcoholic drinks frequently enhances the effects of solvent exposure... tolerance for alcohol is reduced... a worker heavily exposed during a shift may be just as dangerous on the road as someone whose blood alcohol is over the limit.” Main effects are drying, cracking, reddening skin; dermatitis; toxic effects on liver, kidneys, and cardiovascular system, on the central and peripheral nervous systems and “general lassitude with tiredness, sleep disturbances and lack of motivation.”
*From WHO (via Toxins Awareness Group): paint solvents are carcinogenic, painters having a 40% higher chance of lung cancer and 20% higher of stomach, bladder, larynx, etc cancers, while their children are at increased risk of leukaemia and brain tumours.
*From the NZEPMU printers’ seminar 1998, on solvent neurotoxicity: 50% of solvent neurotoxicity comes from the printing industy. From Prof Bill Glass’s introduction: solvents cause abortions and affect sperm. Measured air levels don’t include skin absorption. For toluene, hippuric acid is tested in urine - the levels rise and fall depending on work exposure. [Toluene and benzene were discovered in the headspace above X-ray processing solutions.] Solvents accumulate in fats and are excreted more slowly. One story: that of the bloke whose wife made him sleep facing a new tallboy (because he breathed fumes on her all night - many solvents are excreted through the respiratory system) and stripped the finish off part of it by the end of the year. Those affected often become aggressive both at work and at home. It is common to find marriages and relationships falling apart.
*From David Appleby, OSH, NZ: Many WES (Worker Exposure Stds) are still set too high for solvents and anaesthetic gases to prevent solvent neurotoxicity and adverse pregnancy outcomes. These limits are political. The lower the WES the more toxic the chemical. A chemical with a WES of 25 is four times more toxic than a WES of 100. Also WES are based on studies of healthy males. He suggested his experience is that women are more sensitive to, and experience more harmful effects from solvents than men. Women can consume only 2/3 the alcohol of men. [Like Asians, women have less alcohol dehydrogenase enzyme] ?similar for solvents. There is some evidence that solvents not soluble in water cause more harm and more readily enter the bloodstream. [See Anaesthetics p 18]. Benzene is an example - see the SNFTAAS’ Bibliography on our web page: Medinsky MA, Determinants of gas and vapour uptake in the respiratory tract, CIIT, 16, 2, 1996, or www.ciit.org/ACT96/ACTIVITIESMAR96/mar96.html]
Also the metabolites of benzene (eg 2,5-hexanedione) are more neurotoxic than the parent compound.
*From NIOSH - Organic Solvent Neurotoxicity 1987: Exercise increases breathing and heart rate and can lead to increased solvent uptake through the lungs, eg one study showed a 28% increase in zylene uptake. Ethanol modifies solvent metabolism: 7 volunteers who drank ethanol (alcohol) and inhaled toluene had a higher blood concentration of toluene than when no alcohol was drunk. It was thought this was because of competition for alcohol dehydrogenase necessary for the metabolism of both.
But in another study, 33 workers who regularly drank alcohol had significantly lower blood toluene concentrations than other workers who seldom drank. This suggests chronic ethanol ingestion induces solvent metabolising enzymes in the liver and thereby lowers blood solvent concentrations.
*Significant associations with spontaneous abortion were found for exposure to formalin, toluene and zylene in women working in pathology and histology laboratories 3 or more days a week. This agreed with some earlier studies but because of the multi-exposure to chemicals the results have to be interpreted cautiously.  Toluene is certainly implicated here.
*Birth Defects Found In Babies of Women Exposed to Solvents. Wall Street Journal, 24 March 1999, A6. A study published in the Journal of the American Medical Association found that pregnant women exposed to organic solvents at work are 13 times more likely to have a baby with major birth defects, and are at increased risk for miscarriages, low birth weight, fetal distress, and prematurity. Organic solvents are found in paints, pesticides, adhesives, lacquers, and cleaning agents, and the study found more problems in women employed in factories, laboratories, graphic design or printing businesses, and as chemists. Dr. Richard Schwarz, an obstetrics consultant to the March of Dimes, warned that the study group was too small to reach definitive conclusions at this point.
*The aromatics which have replaced lead in petrol are toluene, zylene, benzene, mesitylene and dimethyl-benzene. “The data leaves no doubt that additives are thoroughgoing highly potent carcingogens”. It’s much safer to fill your mower, outboard, chainsaw... with leaded petrol.
*MEK or 2-Butanone (an organic solvent - also called methyl ethyl ketone, methyl acetone) is found in vehicle exhaust; off-gasses naturally from trees; off-gasses formaldehyde when burned. Used in/for adhesives, foil, cleaning products, dental adhesive, film, vinyl, food flavouring, glue, gums, laquer, synthetic leather, lube oils, paint stripper, transparent paper, paraffin wax, perfume, pesticide inert, plastic, printing ink, resin, rosin, synthetic rubber, varnish. (Our Toxic Times, p 9, Dec, 1998).
*ACTA Update, No 37, Oct 1997: Neurotoxicity - An Overview E G Hilary: “...Since WW2 there have been 600 million synthetic chemicals unleashed on the world... The human nervous system is designed to be extremely sensitive. It registers the slightest sound, the touch of a feather over skin, the subtlety of conceptual thinking .... stress is a hackneyed diagnosis... rare brain cancer glioma is increasing astonishingly.... neurobehavioural testing in populations chronically exposed to neurotoxins is vital... ”
Inerts: the secret pesticides. Inerts are the ingredients in pesticides which do not have to be specified. EPA lists over 1400 of these including solvents, stabilisers, and preservatives. Linguistic gymnastics allow tricky manouvres. Inerts include glycol ether, xylene, toluene, formaldehyde and glutaraldehyde. (NCAP - Internet: http://www.efn.org/~ncap/ActiveInertsRel.htm). 71 different solvents were identified in 8,000 pesticides in 1993, (particularly xylene). The solvent may explain the increases in the risks for leukemia and non-Hodgkins lymphoma in farmers.
Niklasson M et al. Are deficits in the equilibrium system relevant to the clinical investigation of solvent-induced neurotoxicity? Scan J Work Envir Health. 23, 3, 206-13, June 1997.
Niklasson M et al. Audiological disturbances caused by long-term exposure to industrial solvents. Relation to the diagnosis of toxic encephalopathy. Scand Audiol. 3, 27, 131-6, 1998
Edling C et al. Long-term follow-up of workers exposed to solvents. Br J Ind Med. 47,2, 75-82, 1990
Howard Keir. Risks vary regarding solvents in industry. New Zealand Doctor in Practice. 3 March 1994.
Taskinen H et al. Laboratory work and pregnancy outcome. JOM, 36, 3, 311-319, 1994.
Greenway R D. Leaded vs Unleaded. Pacific Ultralights. May 1998, p11.
Petrelli G et al. Solvents in Pesticides. Scand J Work Envir Health 19, 6, 1993.
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