No it is not poisonous.   It's practically non-toxic.   It is soluble in water but is rapidly removed by exposure to air.

It's the propellant that replaced CFC's in hair spray cans.

DME is much easier to remove from water than MtBE, since it is a gas and MtBE is a liquid with a fairly high boiling point.

DME has an atmospheric half-life for a few days.

DME is the perfect fuel.

It can, under some conditions act as a mild anesthetic, but nearly so well as its cousin ethyl ether.