On the issue of chemical weapons use during the Iran-Iraq war, I recommend A Poisonous Affair: America, Iraq, and the Gassing of Halabja by Joost R. Hiltermann
However the use of biological weapons does not seem to be as well-known or well-investigated.
For example, there were several reports of "Yellow Rain" (T-2 tricothecene mycotoxins) used against Iranian troops.
UN investigators visting Iran confirmed the use of chemical weapons including mustard gas and nerve agents but not mycotoxins (1)
Tests performed by Dr. Herbert Mandl at the Toxicological Institute in Ghent, Belgium, on several Iranian battlefield victims of Iraqi chemical weapons who had been sent to Vienna and Stockholm for treatement, revealed "with certain proof" the presence of mycotoxins mixed with mustard gas.(2)
Based on previous (controversial) allegations of similar weapons used against the Hmongs in Vietnam/Cambodia, the Wall Street Journal declared:
"We can confidentally assume that the identification of mycotoxins in the Iran-Iraq war represents yet another Soviet violation of the Biological Weapons Convention of 1972".(3)
However, the Washington Post later reported the existence of several undisclosed reports (due to "political sensitivities") about a German role in Iraq's bio-weapons programs which involved mycotoxins, among other things:
"Six German firms supplied some of the equipment Iraq needed to make botulin toxin and mycotoxin germ weapons, including devices that allow germs to grow in laboratories, concentrate pathogens, protect workers from contamination and allow technicians to traverse a contaminated battlefield."(4)
And Japanese scientists were also implicated in Iraq's program to produce mycotoxins:
"According to a 1991 US military intelligence memo, Japanese scientists had been assisting scientists from Basra University since 1984 in researching mycotoxins produced by soil fungi, including aflatoxin. The Japanese-Iraqi team used three species of aspergillus mold to produce aflatoxin." (5)
I am not aware of much else being disclosed about Iraqi use of mycotoxins since then. This would have been the first confirmed use of mycotoxins in war but the issue seems to have simply melted away.
(1) U.N. TEAM SAYS CHEMICAL ARMS WERE USED IN IRAN New York Times. (Late
Edition (East Coast)). New York, N.Y.: Mar 27, 1984. pg. A.5
(2)TOXINS ARE REPORTED IN IRAN TESTS AP (NYT); Foreign Desk March 11,
1984, Sunday Late City Final Edition, Section 1, Page 14
(3)New 'Yellow Rain' Victims Wall Street Journal; Mar 12, 1984; p.28
(4) German Firms Primed Iraq's War Machine Series: SENDING EQUIPMENT TO
IRAQ: Anatomy of a Deal Series Number: 2/2; [FINAL Edition] R. Jeffrey
Smith, Marc Fisher. The Washington Post Jul 23, 1992. pg. a.01