Sep 21, 2015 0 Comments in Neurotoxicity, Solvents, Uncategorized by

A recent article published by the Center for Public Integrity highlights the dangers of a common solvent, methylene chloride. The author describes a number of deaths attributed to methylene chloride, as well as a some legal cases that have been pursued for methylene chloride injuries. Methylene chloride is contained in widely available paint stripping products. The author decries the lethargic response of regulators concerning this product.

There was little information in the article about toxic outcomes of solvents such as methylene chloride that fall short of death but are debilitating outcomes. I have been involved in evaluating some cases where methylene chloride was suspected to have contributed to neurotoxicity.

The author of this article, while admirably focused on the lethal consequences of methylene chloride, did not identify and describe another important and widespread outcome of methylene chloride toxicity: the deterioration of neuropsychological function. This outcome is often missed because it requires an interdisciplinary approach to the evaluation of illness, involving both neuropsychology and neurotoxicology. Although the material safety data sheet for the product methylene chloride refers to nervous system toxic effects, it also fails to adequately warn users of possible neuropsychological decline from a toxic exposure to this product.

I published an article on this topic in 1996, and presented my research at an annual meeting of the Society of Toxicology in 1996. Below, I reproduce the abstract of this paper.


Raymond Singer, Ph.D., Santa Fe, New Mexico

 46 year old man was priming a fiberglass boat with a product containing 90% methylene chloride (MC). He worked outdoors, air temperature in the upper 80’s F., on a calm day, in an area that was protected from wind. The subject worked underneath the boat about 70% of the time. The boat was elevated two feet above the ground, and his head was about 12-18 inches from the surface being primed. About a quart of the primer was used over the 3.5 hours of work time. MC is denser than air, and fell into the subject’s face. Based on modeling, his exposure was estimated to be about 5,000 – 7,000 ppm, while the proposed OSHA standard is 25 ppm. After the bottom was primed, he began to paint the bottom with anti-fouling paint. He fell unconscious, and friends who were nearby dragged him out from under the boat. He was unresponsive for less than one minute, and then was disoriented and appeared intoxicated. He complained of a headache, which he reports to date, and was observed to be forgetful, clumsy, and with poor visual-spatial judgement. Five days later, he presented at the local hospital and was diagnosed with methylene chloride poisoning. Methylene chloride is partially metabolized to carbon monoxide, and it’s toxicity is a combination of solvent toxicity (narcosis, anesthesia) and CO toxicity (carboxyhemoglobinemia). Upon multiple neuropsychological examinations by more than one examiner, the subject was found to have deficits incompatible with his prior high level of social and vocational function. He was positive on the Neurotoxicity Screening Survey, showing symptoms consistent with neurotoxicity; estimated to have a pre-exposure IQ of 138; current performance IQ of 121; Paced Auditory Serial Addition Test <1%; and deficits in memory and emotional function. Memory consolidation was impaired; the subject forgot that he had been examined when questioned two weeks later. He was unemployable due to deficits in attention, memory and perception.


Singer, R. (1996, March). Neurotoxicity from outdoor, consumer exposure to a methylene chloride product. Fundamental and Applied Toxicology, Supplement: The Toxicologist, 30, 1, Part 2.

Singer, R. (1996, March). Neurotoxicity from outdoor, consumer exposure to a methylene chloride product. Society of Toxicology Annual Meeting, Anaheim, March 11.

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