You also can't proves deaths weren't caused by nitrates in meat.

Most of the studies involving nitrates are epidemiological studies looking  
for correlations between nitrates and cancer.  Even if these studies  
aren't crap, which the vast majority are, and even if the statistical  
significance is high (most are abysmally low, low enough to be caused by  
chance), these types of studies do not prove causation.  In other words,  
even if 100% of the people who eat nitrates die from cancer, it's not  
necessarily true that nitrates cause cancer.  (And in terms of  
percentages, the actual percentages for these studies are shockingly low,  
and the only reason they even appear large is because the studies authors  
inflate the statistics by using relative risks.)

I believe that there are studies enough. I quote two web links and a
full story from USA Today below. The higher risk does not mean that
everyone gets it, so perhaps you are luckily immune. The link is still
established. Beyond these kind of studies, there is a known mechanism
for it as the nitrates convert to nitrosamines in the stomach. Knowing
what kind of terrible effects a cancer might have, I don't think that it
is being overly conservative to avoid the high level of these substances
found in foods like smoked fish and bacon. I feel quite safe with the
very low levels in cheese.

http://www.waternet.com/newsprint.asp?print=1&mode=4&N_ID=21690
http://caonline.amcancersoc.org/cgi/content/full/55/3/143

The following is a quotation from USA Today.

    06/22/2001 - Updated 05:18 PM ET

    LYON, France (June 23) - Eating lots of preserved meats such as
salami, bacon, cured ham and hot dogs could increase the risk of bowel
cancer by 50 percent, early results of a major new study have
    suggested.

    However, when it came to fresh red meat - beef, lamb, pork and veal
- there seemed to be no link.

    Previous studies have linked high meat intake to colorectal cancer,
but almost all the studies grouped fresh and processed meats together.

    The latest findings come from an ongoing study experts say is the
most reliable research into the influence of diet on cancer to date - an
investigation involving almost half a million people, from southern
    Greece to northern Norway. However, that does not mean red meat has
been cleared of suspicion, said Dr. Arthur Schatzkin, chief of
nutritional epidemiology at the U.S. National Cancer Institute.

    ``These results are very preliminary,'' said Schatzkin, who was not
involved in the study. ``There's more narrowing down that has to be done
before we can draw any conclusions.''

    The study, presented Friday in Lyon at the European Conference on
Nutrition and Cancer, is being coordinated by the World Health
Organization's International Agency for Research on Cancer.

    Experts say the findings show the issue is more complex than
previously thought, and that it's not as simple as meat being either
cancer-promoting or not. Scientists are learning that factors such as
    cooking methods and duration, and cuts of meat must also be
considered.

    Some research has suggested that frying or barbecuing may add
cancer-promoting chemicals to meat and that a crispy lamb chop or a
well-done steak may contain undesirable compounds.

    ``This points us in the direction we need to go. The only firm
conclusion is that lumping fresh and processed meat together is
inappropriate,'' said Martin Wiseman, a professor at the Institute of
Human
    Nutrition in Southampton, England, who was not involved with the
research.

    ``But now, what about hamburgers? Are they processed or fresh meat?
And meatballs? Where do they fit in? We are just starting to disentangle
all this,'' Wiseman said.

    The study's coordinator, Dr. Elio Riboli, chief of the nutrition
division at the International Agency for Research on Cancer, told
scientists no link was seen when all red meat was examined as one group.

    But when the processed meat, which is usually red meat, was
investigated alone, those who ate an average of 2 ounces per day - the
equivalent of a thick slice or two of smoked ham, four slivers of
    Parma ham or one giant hot dog - had a 50 percent greater chance of
developing cancer of the colon or rectum than those who ate no preserved
meat.

    ``However, we could not, so far, take into account cooking methods
in our analysis,'' Riboli said. ``So we could not, for the time being,
separate red meat consumption depending on whether it was
    consumed well done or rare. Therefore, these are just intermediate
results.''

(USA Today 22/6-2001)