Googlel the active ingredient. add a phrase 'is it systemic' .. if it is, then i wouldn't use it. if it does not persist in the plant, then it'll probably be okay. then, you have to look up half-life.
1 x .5 x .5 x.5 x.5 = 6.25% remains after 4x half-life length of time... just how to conceptualize, not saying 6.25% is safe.
e.g. neem is a 2-day half life? so in 15-16 days or so it's pretty much gone.
don't trust ppl. fine real scientific rundown on the active ingredient, or ingredients. google will have that sort of detail for you. some individual not educated on teh topics will have no clue.