KNOW short tail & bioconcentrate?

Question

I came across the two words which i don't know ; the original sentense is given in the brackets
1) short tail ( its a health effect of MIrex-chemical)what is it?
2.) bioconcentrate(bioconcentrate in fish & slowly photo degrade)

Answer 1

"Short tail" does not refer to human health.
The effect of mirex (and other chemicals) is studied on rats. So "short tail" literally means that new-born rats which come from female rats that were exposed to the chemical during pregnency develop short tails.

http://www.epa.gov/iris/subst/0251.htm

As far as bioconcentrate is concerned I think wikipedia explains it very well:
Bioaccumulation can be divided into bioconcentration and biomagnification. Bioconcentration considers uptake from the non-living environment while biomagnification describes uptake through the food chain. For many fat-soluble and persistent chemicals (POP's), biomagnification is the dominant factor.

http://en.wikipedia.org/wiki/Bioconcentration

or more simply...Some chemicals cannot be expelled from the body, so if you eat something contaminated with one of them then it accumulates/concentrates in your body