Tetraethyllead is highly toxic, with as little as 6-15mL being enough to induce severe lead poisoning.[63] The hazards of TEL's lead content are heightened due to the compound's volatility and high lipophilicity, enabling it to easily cross the blood-brain barrier and accumulate in the limbic system, frontal cortex, and hippocampus, making chelation therapy ineffective.
Early symptoms of acute exposure to tetraethyllead can manifest as irritation of the eyes and skin, sneezing, fever, vomiting, and a metallic taste in the mouth. Later symptoms of acute TEL poisoning include pulmonary edema, anemia, ataxia, convulsions, severe weight loss, delirium, irritability, hallucinations, nightmares, fever, muscle and joint pain, swelling of the brain, coma, and damage to cardiovascular and renal organs.[64]
Chronic exposure to TEL can cause long-term negative effects such as memory loss, delayed reflexes, neurological problems, insomnia, tremors, psychosis, loss of attention, and an overall decrease in IQ and cognitive function.[65]
The carcinogenity of tetraethyllead is debatable. It is believed to harm the male reproductive system and cause birth defects.[66]
Some neurologists have speculated that the lead phaseout may have caused average IQ levels to rise by several points in the US (by reducing cumulative brain damage throughout the population, especially in the young). For the entire US population, during and after the TEL phaseout, the mean blood lead level dropped from 16 μg/dL in 1976 to only 3 μg/dL in 1991.[68]