"Encephalopathy" is a general term describing brain malfunctions and "toxic" asserts that the malfunction is caused by toxins on the brain. The most prominent characteristic of toxic encephalopathy is an altered mental status. Acute intoxication is a reversible symptom of exposure to many synthetic chemical neurotoxicants. Acute intoxication symptoms include lightheadedness, dizziness, headache and nausea, and regular cumulative exposure to these neurotoxicants over a number of years puts the individual at high risk for developing toxic encephalopathy. Chronic exposure to low levels of neurotoxic chemicals can also cause reversible changes in mood and affect which resolve with cessation of exposure. Acute and chronic toxic encephalopathy on the other hand, are persistent changes in neurological function that typically occur with exposure to higher concentrations and longer durations respectively. The symptoms of acute and chronic toxic encephalopathy do not resolve with cessation of exposure and can include memory loss, dementia, small personality changes/increased irritability, insidious onset of concentration difficulties, headache, lightheadedness, ataxia, involuntary movements (parkinsonism), fatigue, seizures, arm strength problems, and depression. A paper by Feldman and colleagues described neurobehavioral effects in a 57-year-old house painter with regular exposure to large amounts of solvents.