Toxic Tuesdays

CHEJ highlights several toxic chemicals and the communities fighting to keep their citizens safe from harm.


Toluene is one of the most heavily produced chemicals in the US and the world. This chemical is utilized as an industrial solvent in the production of many commonly used materials such as paints, paint thinners, rubber, fingernail polish, lacquers, adhesives, and used extensively in the pharmaceutical industry.

Toluene is a clear, colorless liquid that is found in vapor form at room temperature. A common sign of significant toluene concentration in the air is a sharp and sweet odor. At this concentration in ambient air, toluene can be a fire hazard given the fact that it can become flammable at temperatures above 40°F.

The main route of exposure to toluene is through inhalation. Once inhaled, toluene is easily absorbed by your lungs and dispersed through the body, even crossing the blood-brain barrier due to how easily it dissolves in fats (highly lipophilic). The result is a myriad of central nervous system (CNS) problems including headaches, dizziness, ataxia, drowsiness, euphoria, hallucinations, tremors, seizures, and even coma; as well as respiratory, cardiovascular, and reproductive/developmental effects.

Acute exposure to high levels of toluene (≥500 parts per million) can result in multiple CNS problems within 30-60 minutes of exposure. The respiratory system can develop irritated mucous membranes and liquid accumulation in the lungs, which can lead to respiratory arrest. Finally, even short exposures to elevated levels of toluene can result in irregular heart rhythm, making cardiac arrest much more likely after intense to moderate physical activity.

Prolonged exposure to toluene levels as low as 200ppm can cause chronic CNS problems such as headaches, fatigue, nausea and difficulty sleeping. Chronic irritation of the upper respiratory tract and sore throat have been reported in people exposed to small amounts of toluene for an extended period of time. Pulmonary lesions have been documented in long-term animal studies, so this can be a potential health complication for humans. Finally, although toluene has not been confirmed as a reproductive hazard, it is able to cross the placenta and is accumulated in breast milk, meaning that it can easily reach a developing fetus or newborn.

In developing countries, toluene has become a cause for major concern due to a practice among children and young adults called glue sniffing. Glue sniffing is a form of substance abuse common in many developing countries due to its relatively inexpensive nature. The high and euphoric feelings that it produces are partly due to the ability of toluene to easily enter the central nervous system and create hallucinations and euphoria. A number of studies around the world, including in places such as SingaporeSouth Africa; and India, have documented this practice and have offered insights into how to combat this practice.

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