Ingested toxicity is very low, in fact, if you go on the Atkins diet, your body makes ketones as a waste product. Treat it like any other stuff you don't want your 7 yr. old playing with, but "too dang dangerous", I don't think so.
Sorry, but I have to comment on this. I don't know the biological effects of MEK (check the MSDS, among other things), but saying that it's not that dangerous because the body makes ketones is extrapolating way too far from a single data point. Ketones are a very broad class of organic chemicals; they are, chemically speaking, any two alkanes (methane, ethane, propane, butane, et seq.) bound by a C=O group in the middle (that's a carbon atom and an oxygen atom with a double bond). MEK, then, would be methane (CH4, drop one H to give it a place to bond, so CH3) bonded to the C=O, bonded to an ethane (C2H5, remember to drop one H). Even though they're all still ketones, dimethyl ketone, di-ethyl ketone, butyl-methyl-ketone, and so forth are all different compounds, with different properties.
To put this in perspective, consider this: alcohols are
also just hydrocarbon groups, but the functional group is an OH tacked onto one end. Ethanol (ethyl alcohol) is C2H5OH. Methanol (methyl alcohol) is CH3OH.
Ethanol and methanol are both alcohols. Ethanol is good stuff (particularly in the form of Talisker, Laphroaig, or other fine single-malt). Methanol will kill you dead (after it blinds you).
Don't extrapolate based solely on the fact that they're the same broad category of chemicals. CHECK THE MSDS.
(Somewhere, my chem teacher is smiling, even if I did have to look up the functional groups.)
