"other" dioxins

[astile@mailhost.dpie.gov.au]

I am seeking information of RELATIVE toxicities of the various dioxins.

2,3,7,8-tetrachloro-dibenzodioxin "2,3,7,8-TCDD"  is what is generally
called "dioxin".  I have references to the higher chlorinated dioxins, but
is there any published work on any of the following?

1,3,6,8-TCDD
2,3,7-trichloro-dibenzodioxin
2,7-dichloro-dibenzodioxin
dibenzo-dioxin   (with no chlorines)

I assume that these chemicals with fewer chlorines are less persistent in
the environment and are therefore considered less of a "health" concern, but
the assumption that they are less toxic???

Allen