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  • From: "Tradingpost" <tradingpost@lobo.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Pancreatic Cancer Linked to Herbicides
  • Date: Wed, 03 Jun 2009 21:31:42 -0600


Pancreatic Cancer Linked to Herbicides
http://www.sciencenews.org/view/generic/id/44163/title/Pancreatic_cancer_lin
ked_to_herbicides_
* Some weed killers may need to be treated with more respect
By Janet Raloff
Science News, May 28, 2009

A new study links two weed killers with pancreatic cancer in pesticide
applicators and their spouses. The authors, most of whom work for the
National Cancer Institute, note that they are the first to link this
particular malignancy with the farm chemicals — pendimethalin and EPTC
— and really don’t know how either would trigger cancer (although they
do have a theory). But for now they are recommending that “these findings
should be considered hypothesis generating and in need of confirmation.”

How’s that for not hyping your data?

Pancreatic cancer is a rare disease and nearly always fatal. Producing few
early symptoms, the disease is usually diagnosed once the cancer is
advanced. But even where the cancer is found fairly early and removed, only
one in five patients survive five years. And there is basically no cure.
Which explains why this malignancy is the fourth leading cause of cancer
deaths in the United States.

With such a poor prognosis, there’s been a push to understand what might
predispose someone to develop the disease. Cigarette smoking seems to
double risk, and a host of other factors also up the odds that someone will
get this cancer — such as obesity, chronic pancreatitis, diabetes,
cirrhosis and chewing tobacco. Taken together, however, these risks still
only explain about a quarter of cases.

A couple epidemiological studies had suggested that certain agricultural
chemicals, principally weed killers, might spike someone’s risk. So
Gabriella Andreotti of NCI’s division of cancer epidemiology and
genetics, in Bethesda, Md., and her colleagues decided to probe risks of
the disease among the 89,000 participants of a long-running federally
funded Agricultural Health Study. Its participants include 57,000 private,
licensed pesticide applicators (mostly white men) and some 32,000 wives of
applicators. All lived in Iowa or North Carolina when they were recruited
in the mid-1990s.

Throughout the first seven years of followup, 93 cases of pancreatic cancer
developed — 64 in applicators, the rest in spouses. As in other studies,
smoking, having diabetes, or tipping the scales at an undesirable weight
all increased an individual’s odds of developing cancer. But after
adjusting for these risk factors, two of some 50 pesticides showed a
statistically significant correlation with the cancer.

Farmers treat their fields with pendimethalin (sold under such trade names
as Accotab, Go-Go-San, Herbadox, Penoxalin, Prowl, Sipaxol, Stomp and
Way-Up) to get rid of certain annual grasses and broadleaf weeds that
threaten their corn, potatoes, rice, cotton, soybeans, tobacco, peanuts and
sunflowers. The other herbicide, EPTC (also known as Eptam, Eradicane,
Shortstop and Genep), targets grassy and broadleaf weeds in fields planted
with beans, forage legumes, potatoes, corn and sweet potatoes.

These were the only two pesticides that seemed to increase pancreatic
cancer risk in an exposure-dependent manner, Andreotti's group reports in
the May 15 International Journal of Cancer. That is, cancer risk increased
40 percent among people who had incurred moderate exposure to pendimethalin
or had employed lots of protective gear when applying. Among mores highly
exposed individuals, the pancreatic cancer risk was triple the rate seen
among those applicators never exposed to this herbicide. Similarly, there
was an 80 percent increased risk for relatively low-level exposures to
EPTC. That risk jumped among the more heavily exposed individuals to
two-and-a-half times the cancer risk in pesticide applicators who had never
used this chemical.

Although Andreotti’s group acknowledges that the mechanisms by which
either chemical might trigger pancreatic cancer remain unknown, they
suspect it might have something to do with the fact that the one can harbor
the carcinogen nitrosamine as a trace impurity and both weed killers are
able to form related N-nitroso compounds. Nitrosamines and related
compounds are suspected human carcinogens affecting tissues including the
pancreas.

I guess the lesson is that anything we broadcast into the environment at
concentrations expected to kill something should be treated with respect.





  • [Livingontheland] Pancreatic Cancer Linked to Herbicides, Tradingpost, 06/03/2009

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