CHEMICALSChlorine Is a Highly Useful Chemical That’s Also Extremely Dangerous − Here’s What to Know About Staying Safe Around It

By Aliasger K. Salem

Published 27 November 2023

Chlorine is extremely toxic, and because it’s ubiquitous in many industries across the U.S., it often is released in chemical accidents and spills. As with other household chemicals, it is very important to understand its risks, read labels before using it, store it in its original container in a secure place and dispose of it safely.

Many people encounter chlorine in their daily lives, whether it’s as an ingredient in household bleach or an additive that sanitizes water in swimming pools. Chlorine is also used as an antiseptic, a bleaching agent in the production of paper and cloth, and to kill microorganisms in drinking water.

But this familiar chemical is also extremely toxic. And because it’s ubiquitous in many industries across the U.S., it often is released in chemical accidents and spills.

As a pharmaceutical scientist, I study ways in which chemicals and other materials affect the human body. Currently, I am working to develop therapies to counteract chlorine gas exposure and to understand the mechanism by which chlorine harms people. One promising therapy that we are developing is inhalable nanoparticles that counteract lung damage following chlorine gas exposure.

A Common and Dangerous Chemical
Chlorine is an extremely toxic and widely used chemical. In the U.S., it is one of the top five chemicals by production volume, with an output of about 12 million tons (11 million metric tons) per year.

A yellow-green gas at room temperature, chlorine is highly reactive, which means that it readily forms compounds with many other chemicals. These reactions often are very intense. Chlorine reacts explosively or forms explosive compounds with many common substances, including hydrogen, turpentine and ammonia.

Chlorine gas exposure, even for short periods of time and at low levels, leads to eye, throat and nose irritation and causes coughing and breathing problems and burning in the eyes. Higher exposure levels can cause chest pain, severe breathing difficulties, pneumonia, vomiting and fluid in the lungs. Very high levels can cause death. Chlorine also can be absorbed through the skin, resulting in pain, swelling, inflammation and blistering.

Our research has shown that exposure to chlorine gas leads to airway inflammation and airway hyperreactivity – swelling and narrowing of the bronchial tubes that carry air to and from your lungs, which makes it harder to breathe. This condition is a characteristic feature of asthma.

Chlorine’s toxicity made it one of the first chemical weapons used on a large scale in warfare. German troops released it against French and Canadian forces in World War I. More recently, international observers report that Syria has used chlorine weapons repeatedly in that country’s civil war. In Iraq, insurgents used chlorine bombs against U.S. forces in 2007 in and around Baghdad, and the Islamic State reportedly later used chlorine in crude roadside bombs in Iraq.