why is acetaldehyde less toxic than formaldehyde?

Answer 1

Good question.

Formaldehyde is highly chemically reactive it reacts with just about any cell component.(Handbook of Poisoning by Robert H. Dreisbach) (Less steric hinderance than Acetaldehye?)

Acetaldehyde is metabolized into acetic acid that goes to provide engery in the Kreb Citric Acid cycle, formadehyde forms formic acid, very acidic, but I doubt much is formed since it is so reactive.

The drug Paraldehyde is a trimer of acetylaldehyde which is thougth to be hydrolysed to acetalaldehyde in the liver, orally Paraldhyde can be irritating and also cause necrosis. It has still some use in alcohol withdrawal , and anticonvulsant, and other things. Remember that alcohol is metabolised into acetaldehyde before being made into acetic acid.

Don' trust the Wiki, I find misinformation there from time to time.

Answer 2

At concentrations above 0.1 mg/kg in air, inhaled formaldehyde can irritate the eyes and mucous membranes, resulting in watery eyes, headache, a burning sensation in the throat, and difficulty breathing.

In the body, formaldehyde can cause proteins to irreversibly bind to DNA. Laboratory animals exposed to large doses of inhaled formaldehyde over their lifetimes have developed more cancers of the nose and throat than are usual, as have workers in particle-board sawmills. However, some studies suggest that smaller concentrations of formaldehyde like those encountered in most buildings have no carcinogenic effects. Formaldehyde is classifed as a probable human carcinogen by the U.S. Environmental Protection Agency and as a known human carcinogen by the International Agency for Research on Cancer.

In the liver, the enzyme alcohol dehydrogenase converts ethanol into acetaldehyde, which is then further converted into harmless acetic acid by acetaldehyde dehydrogenase. Acetaldehyde is more toxic than ethanol and is responsible for many hangover symptoms.

As you can see, acetaldehyde can be metabolized by the human body while formaldehyde has a direct action in critical physiological functions.

Good luck!

Answer 3

I don't know the answer, but I'll tell you this...

Go to Wikipedia and search both of them, and compare the substances found in each of the items you listed. The answer to your question may be obvious with the chemicals listed, but I can't be sure.