Dangerous combinations: Household chemicals you should never mix

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A look at household chemicals you should never mix. (KTRK)

Whether you're using pesticides or household cleaners, just one chemical can be dangerous. If combined, they could easily become toxic. Do you know the difference?

Keith McCoy with Solutions Self-Chem says the war against pests is ongoing. No matter what you use to fight them, it's important to remember safety first.

"The label is the law and we want to follow that to the T," McCoy explained.

Unfortunately, ignoring those warnings could be tragic.

Last month, a father in Amarillo was not certified to use a commercial pesticide to kill mice under his home. After he tried washing it away, the fumigant mixed with water created a phosphine gas that seeped into the home.

Four children inside the home died.

The commercial grade pesticide was obtained illegally and not meant for residential use.

That was an extreme case where something as simple as water set off a toxic reaction. Even if you're not using commercial grade pesticides, that doesn't mean you should ignore the label.



"You've got full instructions on how to use the product, the protective equipment that you should wearing when applied," McCoy said.

Besides pesticides, there are household chemicals you should never mix together. UH Assistant Professor of Chemistry Tom Teets says bleach is a common item to be aware of.

"Bleach with ammonia can form a toxic gas called chloramine which can cause respiratory damage if inhaled," Teets said.

Adding bleach to products to increase cleaning strength may cause more harm than good.

"Many household cleaners, particularly toilet cleaners and some drain cleaners have acid in them," Teets said. "If you mix bleach with acid, it can form a chlorine gas which is a green and very noxious gas that can cause respiratory problems. It is very poisonous to breathe in."

Some homeowners like to go green and use vinegar as a cleaning agent. But mixing that with bleach is also dangerous.

"It's going to release a chlorine gas. It doesn't matter what type of acid it is. Any type of acid will cause that to happen and vinegar could do that," Teets said.

For those nasty sink clogs, try to avoid mixing different brand drain cleaners. Some products are acidic, while others may be alkaline. If you combine those together, it could generate a lot of heat.

Teets explained, "That's been known to cause damage to pipes or cause unsafe buildup of pressure inside the pipes. That's been known to be a physical hazard as well."

Bottom line, stay safe and read all labels.

Take a look at chemicals you should never mix together:

  • Rubbing alcohol and bleach: When blended, this combination makes chloroform. You can also form chloroform by mixing acetone with bleach. Acetone is commonly found in nail polish remover and in certain paint or varnish removers.


  • Ammonia and bleach: This combination is dangerous, producing vapors that can cause severe damage to your respiratory system.


  • Vinegar and bleach: If you add a weak acid to bleach, it creates vapors of toxic chloramine and chlorine. These vapors can cause serious chemical burns to your eyes and lungs.


  • Drain cleaners: Some drain cleaners are alkaline (basic), while others are acidic. The alkaline drain cleaners sometimes have bleach, which when mixed with acid produces chlorine. Another potential hazard of mixing acidic and alkaline drain cleaners is that when they react they can generate a lot of heat, which could damage PVC pipes or cause dangerously high pressures that can burst any type of pipe. This has caused problems in the past when people dump one drain cleaner down the drain, it doesn't work, and they immediately dump another one in.


  • Baking soda and vinegar: Many people who want to "go green" are convinced that baking soda and vinegar are the ideal cleaning reagents, and they are decent cleaning agents on their own. Nothing dangerous happens when you mix baking soda and vinegar, but basically they neutralize each other and you lose all the beneficial aspects of the two ingredients.
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