Chronic solvent-induced encephalopathy - are Solvents slowly killing you?

Chronic solvent induced encephalopathy (CSE) is a condition induced by exposure to organic solvents, often but not always in the workplace, that lead to a wide variety of persisting sensorimotor  and neurobehavior damage or disease even after solvent exposure has been removed. This syndrome can also be referred to as "psycho-organic syndrome", "organic solvent syndrome", "chronic painter's syndrome", "occupational solvent encephalopathy", "solvent intoxication", "toxic solvent syndrome", "painters disease", "psycho-organic syndrome", "chronic toxic encephalopathy", and "neurasthenic syndrome".The multiple names of solvent induced syndromes combined with inconsistency in research methods can make referencing this disease difficult.

Symptoms

Two characteristic symptoms of CSE are deterioration of memory (particularly short-term memory), and attention impairments. There are, however, numerous other symptoms that accompany to varying degrees.

Neurological

Reported neurological symptoms include difficulty sleeping, decrease in intellectual capacity, dizziness, altered visual perceptive abilities, affected psychomotor skills,, forgetfulness, and disorientation. Neurological signs include impaired feeling at extremities and an inability to sustain a steady motion - a possible effect from psychomotor damage in the brain. Other symptoms that have been seen range from fatigue, decreased strength, and unusual gait. 

Sensory alterations

Studies have indicated that some solvent-exposed workers suffered from loss of smell or damage to colour vision and synergistic exacerbation of hearing loss,

Psychological

Psychological symptoms of CSE that have been reported include mood swings, increased irritability, depression, a lack of initiative, emotional outbursts such as spontaneous laughing or crying etc. Some psychological symptoms are believed to be linked to frustration with other symptoms, neurological, or pathophysiological symptoms of CSE.

Causes

Organic solvents that cause CSE are characterized as volatile, blood soluble, lipophilic compounds that are typically liquids at normal temperature. These can be compounds or mixtures used to extract, dissolve, or suspend non-water-soluble materials such as fats, oils, lipids, cellulose derivatives, waxes, plastics, and polymers. These solvents are often used industrially in the production of paints, glues, coatings, degreasing agents, dyes, polymers, pharmaceuticals, and printing inks.

Exposure to solvents can occur by inhalation, ingestion, or direct absorption through the skin. Of the three, inhalation is the most common form of exposure, with the solvent able to rapidly pass through lung membranes and then into fatty tissue or cell membranes. Once in the bloodstream, organic solvents, due to their lipophilic properties, easily cross the blood-brain barrier. Some common organic solvents known to cause CSE include formaldehyde, acetates and alcohols.

Treatment

Like diagnosis, treating CSE is difficult due to how vaguely defined it is, as well as lack of data on the mechanism of CSE effects on neural tissue. There is no existing treatment that is effective at completely recovering any neurological or physical function lost due to CSE. This is believed to be because of the limited regeneration capabilities in the central nervous system. Furthermore, existing symptoms of CSE can potentially worsen with age. Some symptoms of CSE, such as depression and sleep issues, can be treated separately, and therapy is available to help patients adjust to any disabilities.

History

Cases of CSE have been studied predominantly in northern Europe, though documented cases have been found in other countries. The first documented evidence for CSE was in the early 1960s from a paper published by a neuropsychologist. The paper described a case of workers suffering from carbon disulfide intoxication at a rubber manufacturing company and coined the term "psycho-organic syndrome". Studies of solvent effects on intellectual functioning, memory, and concentration were carried out in the Nordic countries, with Denmark spearheading the research. Growing awareness of the syndrome in the Nordic countries occurred in the 1970s.

Though movements to reduce CSE have been successful, CSE still poses an issue to many workers that are at occupational risk. Statistics published in 2012 claim that at least 20% of employees in many countries still encounter organic solvents at the workplace, and 10% of them experience some form of disadvantage from the exposure.

Occupations that have been found to have higher risk of causing CSE are painters, printers, industrial cleaners, and paint or glue manufacturers - of them, painters have been found to have the highest recorded incidence of CSE. Spray painters in particular have higher exposure intensities than other painters. Studies of instances of CSE have specifically been carried out in naval dockyards, mineral fibre manufacturing companies, and oil & gas industries.