What are the components of comercial weed killer? Are they harmful to human?

Question

What are the components of comercial weed killer? Are they harmful to human?

Answer 1

The best way to get the answer to this question is to visit a garden center or hardware store and go to the weed control section.  Look at the various weed killers and note that some compounds kill all plants, whereas some are specific for different types of plants.  For example, the active ingredient in a broad-leaf weed killer (i.e., kills dicots such as clover and dandelions) is different than the active ingredient in a "kills all" product such as Roundup.

Write down the compounds then come back to the internet and search for the terms.  Toxicity of some of the compounds will probably come up in some of your searches.  You will learn a lot on how to investigate a problem if you do this.

Good luck and enjoy!

Answer 2

The number of past and present weed killers, aka herbicides, are much to numerous to list in this block.  There are multiple graduate level courses involving this one question.  

Are they harmful to humans?  It depends on what you consider an acceptable.  All compounds have the possibility of being toxic.  So in the narrowest sense, yes, all of them are harmful.  But then so is water, oxygen, nitrogen, protein, sugar, starch, fiber, minerals, amino acids and everything else we humans require to survive.

We deal in the real world of acceptable risk.  No decision is without risk, but some decisions are inherently risky (try jumping off the Pike's Peak Bridge with or without a parachute).  The components of the latest group of herbicides have incredibly low risk (granted we are dealing with current knowledge, and that is always limited when compared to future knowledge) as measured by LD50.  Will some of these chemicals result in an unexpected effect.  Yes.  Will all of them?  No.  Consequently, we, the humans, are constantly involved in the decision concerning today's desired outcome as related to tomorrows unknown risk.