Why would anyone think that recycled yard waste would be sterilized before or after composting and what would that do about any insecticides or herbicides that might be on the materials.
You are exposed to much more of those products via the air you breath and the water you drink then y7ou would be from any compost.

Not all compost is good compost. No doubt some unscrupulous composters make a bad product.

A local company here chucks in everything without thought as to the finished product. He heaps it up in large piles over 12 feet high and doesn't blend it well if at all. I've seen pictures of gyproc and truck loads of kitchen wastes all dumped in with horse manure and straw, pushed up in a big pile and left to rot. He has no idea where the straw came from or what it was sprayed with. These kinds of facilities make me cringe.

OTOH, there are guys that work hard at making a good product using good materials and sound composting practices. Proper mix, aeration and monitoring makes for a good compost. Find these guys and you should have no problems. They will be happy to show you what they do, what they use and how they process it. If not, walk away.

I don't know of anyone that "sterilizes" their compost. Maybe you mean reaching thermyphillic temperatures to reduce pathogens and seeds.

Lloyd

Our dump compost is "certified organic". I don't know if they only take vegetative waste from "certified" people or what... But I live in a very "organic" AG area, (Sonoma Co, Ca)
I've never had a problem with it. Nancy

Yes thanks pt03 - I mean thermyphyllic ( we call it sterilising here) with very high temperatures. However my point is some plants which are recycled into green waste bins have been treated with persistent pesticides and the soil around the roots on discarded plants are still contaminated and cannot be cleaned from the compost.
I am fortunate to have a vegetable garden and can control what I put on it but some can only use grow bags for their vegetables and as I stated we have no idea what they may contain.
We must all take care of what we put into the waste which we know will be used for future compost making. To be fair the makers of the compost have no idea what they are using either.

That certain herbicides that are quite persistent and will kill plants growing in it has been known a long time now.
originally that these products were sold was due to ignorance, although today that is not an acceptable reason for continuing to sell the stuff since simple tests will reveal whether any compost has them.
Heating, or getting the compost to heat up, will not do anything to change the problem. If I saw a statement by someone selling compost that they "sterilized" that compost I would run away from that source and never return.

There are only a handful of the persistent herbicides and for the most part are not permitted for domestic use. I don't fret over the domestic yard waste.

Having said that, it is my experience that people will do what ever they want and to heck with the rules.

Testing for these long lasting herbicides was not routinely done (and still isn't as far as I know). If testing does reveal contamination, these composts can still be used for certain crops with no issues.

Lloyd

Here is an FAQ on persistent herbicides from a commercial composting point of view....

Lloyd

Here is a link that might be useful: Persistent Herbicide FAQ

Hello Lloyd, Thank you for the link. Very interesting.

I think we can expect some health issues if we grow vegetables in the compost we buy

If you understand the concept of 'composting' you would know that this is really not a valid concern. Biosolids, or the product that is derived from sewage, can have some concerns about heavy metals which many would prefer to avoid but municipal composting operations derived from recycled yard waste, etc. should pose minimal concerns.

The possibility that they contain persistent herbicides is slim, as laws regarding the composting of material treated with these products - limited to only agricultural, golf courses and some county maintenance applications; no homeowners - require it be composted and reused onsite. And even if some were detected in bagged compost, their only impact is to prevent the growth of certain plants so potential uptake by plants is extremely limited at best.

And molds and fungi are a normal part of the composting process and to be expected if moisture and heat conditions are suitable. They also pose no human heath concern. It may also be useful to know that several common antibiotics were discovered as a result of a composting process. There's good stuff in compost.......not much bad!!

And "certified organic" compost, which is more common than most folks think, is deemed 'organic' after testing specifically for the presence of heavy metals and any other contaminates (like pesticides). It's not that the ingredients need to be certified organic - absolutely NO way to verify that aspect - it's that the output or product is considered organic via the composting process.

There seems to be many people that are either ignorant of, or just close their minds to the legacy of pollution most all chemical companies have left us. Dow, DuPont, Hooker/Occidental, Monsanto, and others have created serious pollution problems in many areas of the world, and lied about doing so often enough that they are not to be trusted at all.

As if only chemical companies cause pollution.

/sarc off/

Lloyd

Here is a link that might be useful: York River contaminated by Gaspé dump

It appears the OP is from the UK ('we call it sterilising' - note the spelling - 'here'). They can call hot composting whatever they want - after all they invented the language. :-]

Knowing what I do about soil contamination and routes of entry into the body, I'm not particularly concerned with pesticide exposure from vegetables grown in compost made from treated plants. There are just too many degradation and dilution steps there for it to be significant. I suspect the exposure is far higher from eating pesticide treated foods, as most people do.

I am quite aware of the 'legacy of pollution', in fact I work in the de-polluting field, but I am not sure what it has to do with the degradability of current pesticides in the compost pile.