The Grazon-90 label makes it abundantly clear that the product is for use only on established grassland. ("Only use GRAZON 90 on permanent pasture or on leys that have been established for at least one year.")
It also makes its persistence into manure / compost very clear. Cut and pasted from the Grazon-90 label (my bolding):
WARNINGS
GRAZON* 90 residues in plant tissues which have not completely decayed may
affect succeeding susceptible crops eg peas, beans and other legumes, carrots
and Umbelliferae, potatoes and tomatoes, lettuce and other Compositae.
Do not plant susceptible autumn-sown crops (eg winter beans) in the same year
as treatment with GRAZON 90. Where susceptible crops are to be planted in the
spring do not apply GRAZON 90 later than the end of July of the previous year.
Following good agricultural practice ensure that plant remains have completely
decayed before planting susceptible crops.
Do not use any plant material treated with GRAZON 90 for composting or
mulching.
Do not use manure from animals fed on crops treated with GRAZON 90 for
composting.So I am sorry, mary, but you have been really rather stupid to use Grazon on manure.
Read on, however, because the stuff seems to persist even further than the manufacturers state in their labelling.
Grazon contains clopyralid. There have been stories in the press for three years at least of crop failures after using manures from herbivores who have eaten hay made from aminopyralid-treated grasses.
Here is one such story:
http://www.geologywales.co.uk/storms/summer-2011-aminopyralid.htmWe spot-spray Grazon from time to time for nettle and thistle control. Any residues in hay or silage give us another hit when the muck from the cattle and sheep who have eaten it is spread back on the pasture. We do have to be careful that it doesn't make it into muck we spread on land ploughed for veg crops, though - or for muck neighbours take for their gardens.
BTW, we have never had any problems with unthrifty lambs.
Oh, and the Grazon label also states that it will irritate eyes and skin, and can cause sensitisation in some people. It makes it plain that operatives using the product should be wearing protective clothing, including gloves. It says that if it gets on your skin you should wash thoroughly - and should also wash any contaminated clothing. So you shouldn't really be letting it get to your skin to cause irritation.