Hmmmmmm well,, lets see,,, As for describing the wonderful world of amines, amides, and pospho groups ill leave that to an organic chemist.
Both DallasMike2U and Enzyme11 have very good observations. I noticed that in the discussion between them they pondered the relative toxicity of table salt, glyphosate, and acetic acid (vinegar). First I would have to say that the word toxic is a very broad term. To me comparing the relative toxicity of glyphosate, table salt, and acetic acid is like comparing apples, mallard ducks, and light bulbs. An LD50 is the dose at witch a substance causes death 50% of the time. Usually the route of exposure is defined such as LD50 via ingestion, or LD50 via intravenous injection. LD50 test are conducted by exposing various animal to the substance in question and hopefully the animal model will allow you to predict the human LD50. Please note that rats are not humans so there is a inherent flaw when one tries to make a precise prediction of a humans reaction to a substance based on an animal model. Listed below are the LD50’s of table salt, acetic acid and glyphosate.
Rat/mouse LD50 via ingestion of glyphosate= 3800mg/kg to 4320mg/kg
Oral Rat LD50 of acetic acid=3310 mg/kg ingested
Exposure to the skin of a Rabbit LD50 of acetic acid=1060 mg/kg
Human oral ingestion LD50 or table salt=3320mg/kg
Round up = 19.2 grams of glyphosate per Liter
That means a 65 kg male (143 pounds) would have to eat .48 pounds of table salt, 3.4 gallons of round up, or .23 gallons of 20% vinegar to have a 50% chance of dieing. If you define toxicity as LD50 then round up is the least toxic of the chemicals both in weight or volume consumed. This may be where they get the saying that round up is less toxic than table salt but to narrow the definition of toxicity to the point where only the LD50, LD 42, LD75, ect. is to be considered would be a complete misrepresentation of its impact on the health of any living thing.
There are many other things you must consider when weighing the health and environmental risks of one using one substance over another for any given purpose. I will only go into a few examples pertaining to table salt, glyphosate, and acetic acid. As of this moment I trust the research (pending further investigation) that has found that doses as low as 38mg/kg ((
http://www.forumue.de/forumaktuell/posi ... 00003.html) frequency of 38mg/kg dose over 6 weeks is undefined in that abstract) causes male reproductive deficits in male white rabbits, and Im sure there are other reputable studies out there that would indicate that there are other various unwanted effects of exposure to varying doses of glyphosate. To the best of my knowledge exposure to acetic acid and table salt doesn’t cause reproductive deficiencies in male white rabbits but I’m sure you could design a method to induce sterility with any of these substances (such as injecting strong acetic acid solutions or or 3 molar NaCl into the testicles of white rabbits causing tissue death). The application of 20% acetic acid as a herbicide by the average gardener will no doubt result in burns of the respiratory mucosa, which in all likelihood will go unnoticed but may exacerbate allergies and/or asthma or increase the risk of you everyday respiratory infection in the sensitive individual. This is due to acetic acids particularly volatile properties (volatile=easily evaporates) were as table salt and glyphosate are not particulary volatile (as far as I know) making it more difficult to inhale when applying properly. (I hate inhaling glacial Acetic acid fumes and 13 M HCL.) There is a much greater potential for burns when there is an accident involving 20% acetic acid as compared to round up or a saturated table salt solution. As far as ingestion 20% acetic acid has a fairly obvious ability to burn or irritate the mouth and upper airway if accidentally spilled in the mouth or nose, where as the immediate and long term effects a of accidental introduction of an equal volume of round up in the mouth or nose of a human (to the best of my knowledge) has not been extensively researched or documented in medical studies. There have been cases of acute poisonings with a glyphosate product in Japan. (See pubmed for abstact of the cases
http://www.ncbi.nlm.nih.gov/entrez/quer ... s=15079922 )
From the information I have gathered so far it seems that before using large amounts glyphosate on a massive agricultural and home gardening scale it would be prudent to do at least 5 more years of research by multiple institutions (my very intentionally vague opinion). That being said I can see no reason why using glyphosate sparingly would be a problem but if you are going through gallons of the stuff a year I would think a reevaluation of your weeding techniques would be in order. I also believe that application should be administered in a fashion that is conducive to quick degradation of the glyphosate. (conditions conducive to quick degradation of glyphosate are a whole different topic)
Ramble, ramble, ramble
I have had a 2 gallon container or round up for about 3 years now and have only used about a third of a gallon. I always use gloves when administering it, and I don’t believe that I have had a enough exposure to it to cause any detrimental effects to me or a white rabbit. In other words at the rate I’m using it in not worried about it but heavy crop dusting with tons of the stuff does give me pause for concern.
THE DOSE MAKES THE POISON.
PEACE