Here's an old post from another site that might help during the Summer grilling season:

From: JFS

Date: 9/27/97

Time: 1:40:52 PM

Comments

Steve, I remember this story well. Here are a few links to
readable summaries of the research:

Lawrence
Livermore National Lab summary of research

C-J
Online (The Topeka Capital-Journal)

Dr.
Dean Edell, of our local ABC affiliate

News Bulletin
from Life Services Supplements

Here's the abstract from Medline. I include this because it
suggests that adding sugar to the marinade increases
carcinogens at grilling times over 20 minutes. So you might
want to leave that out if you insist on really killing your meat.

Food Chem Toxicol 1997 May;35(5):433-441

Effects of marinating on heterocyclic amine carcinogen
formation in grilled chicken.

Salmon CP, Knize MG, Felton JS

Biology and Biotechnology Research Program, Lawrence Livermore
National Laboratory, Livermore, CA 94551-9900, USA.

This study compared heterocyclic aromatic amines in
marinated and unmarinated chicken breast meat flame-broiled on a
propane grill. Chicken was marinated prior to grilling and the
levels of several heterocyclic amines formed during cooking were
determined by solid-phase extraction and HPLC. Compared with
unmarinated controls, a 92-99% decrease in
2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was
observed in whole chicken breast marinated with a mixture of
brown sugar, olive oil, cider vinegar, garlic, mustard, lemon
juice and salt, then grilled for 10, 20, 30 or 40 min.
Conversely, 2-amino-3, 8-dimethylimidazo[4,5-f]quinoxaline
(MeIQx) increased over 10-fold with marinating, but only at the
30 and 40 min cooking times. Marinating reduced the total
detectable heterocyclic amines from 56 to 1.7 ng/g, from 158 to
10 ng/g and from 330 to 44 ng/g for grilling times of 20, 30 and
40 min, respectively. The mutagenic activity of the sample
extracts was also measured, using the Ames/Salmonella assay.
Mutage nic activity was lower in marinated samples cooked for 10,
20 and 30 min, but higher in the marinated samples cooked for 40
min, compared with unmarinated controls. Although a change in
free amino acids, which are heterocyclic amine precursors, might
explain the decrease in PhIP and increase in MeIQx, no such
change was detected. Marinating chicken in one ingredient at a
time showed that sugar was involved in the increased MeIQx, but
the reason for the decrease in PhIP was unclear. PhIP decreased
in grilled chicken after marinating with several individual
ingredients. This work shows that marinating is one method that
can significantly reduce PhIP concentration in grilled chicken.