While morality and the need for the use of the riot control agent is certainly a matter of debate, others have also been concerned about the effects that the substance might have on young migrant children who were seen in the fray.
According to experts, tear gas is not exactly what you think it is, and, in fact, has the potential to have a dangerous and lasting effect on children.
What exactly is tear gas? While there are some different compounds that can be used for this purpose, the most common compound is called chlorobenzylidenemalonitrile, or "CS".
It is often assumed that tear gas is irritating, such as smoke from an onion in the eyes or pepper in the nose. Recent medical research has proven otherwise, says Sven Eric Jordt, assistant professor of anesthesiology at Duke University who specializes in sensory mechanisms
"We discovered that the chemical causes pain by activating pain receptors," says Jordt. I would consider them nerve agents that selectively and very potently hook the nerves of pain. "
Children are especially vulnerable to its effects.
According to the CDC, most of these effects disappear after 15 to 30 minutes, if the person is decontaminated.
That's a key step, because Jordt points out that tear gas is not a gas at all, but rather a solid; A powder that must be heated and mixed with a solvent.
"That's why they can be deposited on the skin, hair, eyes and clothes," he says. "Yes [people] They do not decontaminate, this can cause injuries. "
Children have an even greater risk of injury, both at the time of exposure and afterwards.
"Children are especially at risk because tear gas is heavier than air," says Jordt. "It is present in higher concentrations near the ground, and children, being shorter, are exposed to higher concentrations, and since their lungs are smaller, when they inhale tear gas, the risk of injury is greater."
It affects your long-term health.
These reasons were echoed in a statement by the American Academy of Pediatrics condemning the use of tear gas in migrant families.
"The use of tear gas in children, including infants and toddlers in diapers, runs counter to evidence-based recommendations and threatens their health in the short and long term," says the statement, written by AAP president Colleen A Kraft.
"Children are especially vulnerable to the physiological effects of chemical agents: The smallest size of a child, the most frequent number of breaths per minute and the limited response to cardiovascular stress compared to adults increase the damage of agents such as tear gas".
The AAP also refers to possible psychological traumas, since children who have reached the border "have made terrible journeys".
"We must make every effort not to re-traumatize them," writes Kraft.
And those long-term effects are serious.
In addition to burns and respiratory problems directly after the fact, researchers have recognized several possible long-term health risks for those who have been exposed to tear gas.
"There have been many cases in which exposed people were hospitalized due to lung injuries that take a long time to heal, days or weeks," says Jordt.