How Hazardous Is Proprionic Acid?

[Maine farmer]

I have worked with proprionic acid for several years. It is an effective preservative that inhibits mold and helps make good quality hay that cows find more palatable, expecially in years when the weather is less than ideal for making dry hay. Proprionic acid is also effective as an aid in the fermentation process of converting forages into silage. The vetrinarian we use on the farm has told me that proprionic acid is also produced naturally in the digestive system of ruminants. The benefits of proprionic acid are well known to dairy farmers, and has been used for a very long time.

 

A few years back, the EPA decided to classify and regulate proprionic acid as a pesticide. This seems completely out of the blue to me. I've been exposed to proprionic acic for much of my life, and even been accidentally doused in the stuff once or twice. Yes, it was irritating, and made my eyes water, but I don't think it did me any real harm. Have there ever been any environmental disasters caused by proprionic acid? Is it a carcinogen? Can anyone explain the rationale used by the EPA? I don't recall ever reading or hearing about any public hearings about proprionic acid. Have I shortened my life by having been exposed to it?

[CraigD]

How Hazardous Is Proprionic Acid?

According to the US EPA, not very. (Via my mad googling skills ;)) here's the EPA factsheet for it.

 

I have worked with proprionic acid for several years. It is an effective preservative that inhibits mold and helps make good quality hay that cows find more palatable, expecially in years when the weather is less than ideal for making dry hay. Proprionic acid is also effective as an aid in the fermentation process of converting forages into silage. The vetrinarian we use on the farm has told me that proprionic acid is also produced naturally in the digestive system of ruminants. The benefits of proprionic acid are well known to dairy farmers, and has been used for a very long time.

You pretty much agree with the EPA factsheet.

 

A few years back, the EPA decided to classify and regulate proprionic acid as a pesticide. This seems completely out of the blue to me.

According to the factsheet, propionic acid has been registered as pesticide "since the early 1970s" (I'm surprised that an EPA document isn't more precise), and was reregistered in 1991. There are no restrictions on its use - regulations apply to its labeling:

• if a product contains more than 63% active ingredient (propionic acid or other), it must bear the warning "Wear chemical-resistant gloves, chemical-resistant aprons, chemical-resistant footwear and goggles or face shield when loading application equipment unless a closed loading system is used. Avoid working near high concentrations of spray mist/vapor. Use with adequate ventilation. Wash thoroughly after handling."
  
• Products containing it must say what crops they're intended to be used on
  

I've been exposed to proprionic acic for much of my life, and even been accidentally doused in the stuff once or twice. Yes, it was irritating, and made my eyes water, but I don't think it did me any real harm. Have there ever been any environmental disasters caused by proprionic acid? Is it a carcinogen? Have I shortened my life by having been exposed to it?

Again according to the factsheet, its not dangerous other than as a skin/eye irritant, so you shouldn't be any the worse for you contact with it.

 

Can anyone explain the rationale used by the EPA? I don't recall ever reading or hearing about any public hearings about proprionic acid.

Their reasoning seems pretty common-sensical, with a bit of "high dose" animal testing to be sure it has no unexpected risks. (It caused "lesions of the forestomach, reduced food consumption and growth depression" in the unlucky test ... I assume cows)

 

My guess is that, if the EPA isn't restricting its use, they aren't required to have public hearings. The only people impacted by the 1991 labeling requirements were manufactures of products containing it, who I assume were notified of the requirements, and raised no objections.

 

You mention some newer regulation, though, so perhaps I'm reading an out-of-date EPA publication. Do you have a link to something newer, farming guy - an EPA webpage, magazine or new article, etc, or can you quote some printed document you've received? Otherwise, I'd say your worries about new regulations are over nothing.

[Jorge1907]

It's propionic acid - there's only one R in propionic acid. Anything that kills, mitigates, etc a pest (here bacteria/mold) and that is used in an application regulated by the EPA has to be registered as a pesticide. Propionic acid (one r) is used in some regulated applications as a preservative and therefore must be registered. The EPA did not classify it as a pesticide - someone decided to use it to control microbes in a registered application so that person submitted to the EPA an application and data for the proposed use and EPA registered it. there are no public hearings in this processs - it's paperwork.

 

It has nothing to do with toxicity, natural vs. synthetic or anything else - it's the use. Citric acid is also a registered pesticide. This doesn't mean that propionic or citric acid one buys from any source and for any application is a pesticide - only that sold for the registered purpose in a package with the EPA-approved label can be used for the registered application. And any propionic or citric acid sold in a package without the EPA registered label may not be used for a regulated application - even if it's precise the same stuff sold in a properly labelled package. Bureaucracy at its best!

[Maine farmer]

I can't remember what the exact year was, but It was within the last 7 years that they made a change, although I can't remember the precise wording. We had a visit from the State inspector from the Board of Pesticides a few years ago, and he told me we needed to keep records for it's use just as we would if we used glyphosate for weed controll. The records required for herbicides are quite detailed and must include weather conditions, location of field, time of day, and the amount of product used in each field. Also, if we were to do any custom baling for a neighbor and baled over 200 acres, we would be required to have an applicators license.

 

It has been my experience with goveernment inspectors that there is little consistancy in interpretations of regulations. A few years ago I could not get a straight answer as to what the government definition of a stream is from an NRCS agent. Some seem to consider a drainage ditch to be a stream, and some do not. If we follow the wron advice, we are the ones in trouble, not the advisor. The safest thing to do is nothing!

[Jorge1907]

Understand - I'm sure your inspector knows little if anything but that it's a registered pesticide and therefor all the records must be kept. You don't find the best and brightest working for the feds and there's no reward in the civil service for excellence, only risks if you fail to dot all the i's and cross all the t's.

[CraigD]

I can't remember what the exact year was, but It was within the last 7 years that they made a change, although I can't remember the precise wording. We had a visit from the State inspector from the Board of Pesticides a few years ago, and he told me we needed to keep records for it's use just as we would if we used glyphosate for weed controll.

Since products containing propionic acid have been registered as pesticides for 40 years or so, I bet this change is one in inspection and enforcement procedures, not regulation of the products themselves. Keeping precise records seems to me stupid, inflexible bureaucracy, as the EPA regs say you can use as much of the stuff anywhere as often as you like, but stupidity and inflexibility are hallmarks of bureaucracy, so I’m not surprised (if you’ve read my member page, you’ll see I list “bureaucrat” right after “computer programmer” for my occupation, so I consider myself a professional expert in bureaucracy, though mine is of the medical computing, not environmental, specialty)

 

Also, if we were to do any custom baling for a neighbor and baled over 200 acres, we would be required to have an applicators license.

This makes a bit more sense, as I can see how we might want make sure some fly-by-night companies aren’t rounding up dayworkers at the local 7-11 and having ‘em apply nasty chemicals with nothing but what they wear in off the street. Not applicable to a sensible, experienced guy like you, Farming guy, but making everybody get a license seems not to high a price to pay to save some poor folk from getting hurt by greedy idiots.

 

It has been my experience with goveernment inspectors that there is little consistancy in interpretations of regulations. A few years ago I could not get a straight answer as to what the government definition of a stream is from an NRCS agent. Some seem to consider a drainage ditch to be a stream, and some do not. If we follow the wron advice, we are the ones in trouble, not the advisor. The safest thing to do is nothing!

This has been my experience, too, even in the suburbs where I live.

 

One of these days, I’ll have to tell the woeful tale of my adventures with my county building codes office the time I decided that I’d better replace my home’s crappily built 5 foot tall brick-faced block retaining wall before it fell over, and thought that just because I’d had a class in architecture, could use a CAD program, had a brick mason friend, and am, as I've mentioned before, a professional bureaucrat, I wouldn’t have too much trouble with them, could get a permit and do the job in a few weeks for a couple thousand dollars, and they might even think well of me as a responsible homeowner with an interest in keeping tons of dirt and rubble from collapsing on some luckless passerby. This was not what happened :( - though I finally did get the wall built, and a prettier little piece of brickwork you'd be hardpressed to find. :)

[joekgamer]

Right down the street from my house is a large 1600/1700-era house. The owners (who, in fact, live in it) are not allowed to change the outside of the building at ALL. After a perticularly bad storm, they had to start using a cinderblock to hold up a balcony. Also, there is a detergent bottle sitting out there, sandwiched between two parts of a wooden beam. It seems to be holding part of the house up.

 

But as for the propionic acid, does it have any other negative effects on the environment? It it possible for it to get into a river after it rains?

[CraigD]

But as for the propionic acid, does it have any other negative effects on the environment? It it possible for it to get into a river after it rains?

According to the EPA factsheet and the other sources I've read, propionic acid has no significant environmental impact. This makes sense, as a common source of it is bacteria in human and other animals' sweat glands.

 

In high concentrations, it's an irritant that can damage eyes, skin, or, if consumed, gut linings, but it's rarely used in high concentration, and, as best I can tell, a variety of animals metabolize it, so I don't think it can become concentrated to irritating levels by normal by normal environmental processes. In low concentrations, when produced by bacteria in sweat glands, it can cause acne.

[Jorge1907]

CraigD makes an excellent point. As a pesticide, propionic acid is regulated as tho' it were Agent orange. This is a ridiculous waste of time for folks like farming guy as well as as waste of money in enforcement, esp. as it distracts the enforcement types from real issues.

 

Propionic acid is naturally occuring and is highly biodegradable.