"If not, then someone would have to seek approval of the new inert ingredient
as "inert", which would take several deciduous forests worth of paper to
accomplish."

When I requested EPA approve sodium phosphate as a GRAS inert all I needed to do was ask.  No data at all was requested by the agency.  The procedure was simple.  They took 30 or 60 days to review the request internally to the agency.  They posted a Federal register request for comments for and against listing it as a GRAS inert and waited 30 or 60 days for replies.  They took 30 or 60 days to review the replies.  They took some time for their internal paper work to go thru their system.  And about 9 months after I made the request they put it on the GRAS inert list.  My cost was a few phone calls and one formal request that took a single piece of paper plus an envelope.

Actually, if you understand Ag formulations there really are only a few classes of things needed to make up the inerts.  You always want a surfactant of some kind to wet the active in the spray tank and wet the surface the spray hits.  You often want a clay to prevent the formulation from caking or settling to a rock in the spray tank or to control viscosity of the formulation.  Often clay is used simply as a filler to dilute the active to some low concentration, particularly in consumer products.  If you are making an emulsifiable concentrate you need a solvent to dissolve the active and gets its concentration down to the desired level.  For water based flowables you need a viscosity agent that will give a zero shear viscosity in the 5 to 25 dynes/cm^2 range to provide shelf stability of the formulation.  You occasionally need an anti microbial to prevent feral bacteria and fungi from eating one of your formulation ingredients.  You very rarely need some kind of buffer to maintain a desired pH.  That is why I requested listing sodium phosphate on the GRAS list.

Surfactants - There really are only two kinds of surfactants.  The non ionics such as ethylene oxide - propylene oxide block copolymers.  And ionics such as sulfates or quat ammonium salts which both have a long hydrocarbon back bone.  The hundreds of choices you have in surfactants comes from changing the length of those blocks or the exact nature of the hydrocarbon back bone.  There are so many already examined for tox or environmental issues that you nearly always can claim your new product is simply a twist on an existing product and seldom would need to supply anything much beyond a bit of acute tox data.  You sometimes also need a defoamer to counter the foaming caused by a surfactant.  There are a variety of silicone defoamers listed on the GRAS list.

Clays - There are lots of kinds of clays and the properties and reasons for use are all over the map.  Probably the biggest concern for registration is does your new clay mine have any asbestos in it?  If not it is just dirt and eating dirt is not harmful as every kid demonstrates.

Solvents - There are a ton of different hydrocarbon streams coming off a refinery and some work well in formulating one molecule and awful for the next molecule.  But at the end of the day they are all coming off the refinery and vary by amount of branching and boiling points.  I doubt if anyone has listed a new one in the last 40 years.

Viscosity agents -  The three that are used are various cellulosics, Kelzan and clays.  Anyone using a cellulosic is dumb as a stump and that is being polite.  You all have food products in your fridge that have Kelzan in them to control viscosity and provide mouth feel.  They are non digestible and go straight thru your digestive system unchanged.  Things like Kelzan, cellulosics and clays have long been used in food and medical products and have been so well examined that getting a minor modification listed is pretty easy.

Anti microbials -  These would only be used in aqueous based flowables.  The same parabins used in the bread you buy at the grocery store to slow down mold growth will generally be adequate.  But, there are a whole variety available and listed in case your product is used in something where parabins are not ok such as exterior house paint.

Sticker Spreaders -  We tested every single one of those on the market with our fungicide, herbicide and insecticide products.  They are widely sold as tank mix additives.  I never saw any biological test data that showed that they enhanced the performance of any of our products at all.  Occasionally we saw hints they might hurt a very tiny bit, but it is near impossible to see a 10% change in field tests.  Actually I was always a bit surprised they did not hurt performance more than they did.  I always considered them snake oil.  There is excellent money to be made selling snake oil.  You can be sure if we had seen enhancement of any financial value to the user we would have put them in the formulation rather than having him buy a second pail of stuff because we would have made money from the deal.

I signed off on the registration of a great many Ag formulations.  I never once signed off on a formulation that had any additive that enhanced the activity of the active ingredient.  We looked very hard trying to find such additives but never had any luck at all.  The additives are there to allow the product to be shelf stable for years in warehouse conditions, to allow the user to safely and easily transfer the material from the shipping container to the spray tank, to cause the formulation to rapidly disperse in the spray tank with minimal agitation, to keep the material dispersed so spray nozzles do not clog, to prevent the product from settling over night to the bottom of a partially used spray tank and turning into something on the bottom of the tank that is hard to redisperse and to provide enough wetting of the sprayed surface to minimize run off.  If your formulation does all those things you have an ok formulation.  Then you look for cheaper inerts that will still do all those jobs.

If one or more of those additives killed honey bees I did not care as long as the product was not labeled for use on flowering plants.  If it was labeled for use on flowering plants I still did not care if it killed honey bees, but I sure cared a lot if it killed native pollinators and we made sure not to use ingredients that would kill native pollinators for such products.

People naturally distrust the inerts because they are typically trade secretes.  For many years the whole Ag industry recognized that my company make by far the best water based flowable Ag formulations on the market.  We were sure not going to tell our competitors how to make such good formulations.  And after the industry recognized we had the best on the market by a big margin we kept on working on them and improving them so if anyone duplicated a ten year old product they were still ten years behind us.  It would be really nice from a PR standpoint to just list every single ingredient on the label and get past the lack of trust issue.  But, you simply can not afford to give that information to your competition.  Those types of technical advances are generally not patentable.  You can patent a pencil and you can patent an eraser.  But you can not patent putting an eraser on a pencil and that is what we were doing when we make formulations.

My guess is the inert in BT is more than likely mainly or entirely some kind of clay.  That still leaves you with literally hundreds of different clays to pick from.  There might be some kind of inert to protect the BT from freezing damage also.  But you still have a number of choices.  If there is any surfactant it would surely be one of the non ionics as they are so biologically inert.  There are hundreds of them.

Dick

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