5knives said:
Sorry I can't reference this properly, but I saw an interview several years ago, featuring the man who invented the tests use to detect carcinogens.
He expounded at length on what he called the "ridiculous and misleading uses to which the test was being put."
One scene had him walking through a supermarket produce aisle, pointing out that every item there, especially carrots, was carcinogenic, by the misleading standards some "scientists" were using to get headlines (and grant money.)
Seems like testing is a guaranteed lifetime job. There are zillions of chemicals. A lot of it kinda looks like what Richard Feynman called "Cargo-Cult Science".
You're probably thinking of
Bruce Ames at Berkely. There used to be site up that showed a bunch of naturally occuring substances that coume up positive as mutagens and carcinogens that were present in measurable amounts in a turkey thanksgiving dinner. I cant find the original site anymore, only
this, but it is not as fun as the original.
Ame's point is that plants, fungi, bacteria, and animals (especially insects) have been conducting chemical warfare since forever. If humans couldn't deal with most or many of these natural chemical weapons, there wouldn't be any humans to produce man-made ones. Except in the case of massive doses, the same mechanisms that have dealt with traces of naturally occuring chemicals can deal with man-made chemicals.
Every substance is different and the dose makes the poison. Depending upon substance, the dose may be tiny or huge.
Natural can kill you just as dead as man-made. If you get the chance, hopefully far in the future, talk to Socrates about that.
Here's a nice popular
piece.
"...Of all dietary pesticides that humans eat, 99.99 percent are natural," write University of California at Berkeley cancer experts Bruce Ames and Lois Swirsky Gold in a recent paper for the journal Mutation Research. "They are chemicals produced by plants to defend themselves against fungi, insects, and other animal predators."
Another
And
another
Yet the noted biochemists at the University of California at Berkeley, Dr. Bruce Ames and Dr. Lois Swirsky Gold, have for many years published scientific articles pointing out that about half of the natural pesticides on foods and half the synthetic pesticides are carcinogenic when tested in rats and mice, and that "no diet can be free of chemicals identified as carcinogen in high-dose rodent tests." They note that tests were done on 64 naturally occurring pesticides and 35 were found to be carcinogens found in 79 common plant foods and spices, ranging from broccoli and brussel sprouts to grapefruit and garlic as well as tomatoes and turnips. Ames and Gold point out that this should not be a cause for concern -- eating a varied diet rich in fresh fruits and vegetables provides a good defense.
This from a news letter from the University of California
III. Ames Assails Animal Tests, Calls for Rethinking Their Utility
"Animal cancer tests are conducted at near toxic doses (the maximum tolerated dose (MTD)) of the test chemical for long periods of time, which can cause chronic mitogenesis," and can be thought of as a "chronic wounding, which is known to be both a promoter of carcinogenesis in animals and a risk factor for cancer in humans," Drs. Bruce N. Ames and Lois Swirsky Gold of the University of California (Berkeley) pointed out.
Therefore, they said, "a high percentage of all chemicals might be expected to be carcinogenic at chronic, near toxic doses, and this is exactly what is found. About half of all chemicals tested chronically at the MTD are carcinogens."
They pointed out that this holds for both synthetic chemicals (212/350) and natural chemicals (37/77), while for mold toxins tested at the MTD, 11 out of 16 are rodent carcinogens.
Ames and Gold also contrasted the consumption of natural pesticides in the diet, about 1500 mg per person per day, with the average intake per day of residues of 100 synthetic pesticides, 0.09 mg per person per day.
Additionally, they said, thousands of pyrolysis products are produced in cooking food. Estimating that dietary intake of these products is roughly 2000 mg per person per day, Ames and Gold continued: "Few of these have been tested; for example, of 826 volatile chemicals that have been identified in roasted coffee, only 21 have been tested chronically, and 16 are rodent carcinogens; caffeic acid, a non-volatile carcinogen, is also present. A cup of coffee contains at least 10 mg (40 ppm) of rodent carcinogens (mostly caffeic acid, catechol, furfural, hydrogen peroxide, and hydroquinone)."
They called for comparing the "very low exposures to pesticide residues or other synthetic chemicals ... to the enormous background of natural substances. Pesticide residues (or water pollution) must be put in the context of the enormous background of natural substances, and there is no convincing evidence from either epidemiology or toxicology that they are of interest as causes of human cancer," Ames and Gold urged, adding: "Minimizing pollution is a separate issue, and is clearly desirable for reasons other than effects on public health."
They pointed out that "humans are well buffered against toxicity at low doses from both manmade and natural chemicals. Given the high proportion of carcinogens among those natural chemicals tested, human exposure to rodent carcinogens is far more common than generally thought; however, at the low doses of most human exposures (where cell-killing and mitogenesis do not occur), the hazards may be much lower than is commonly assumed and often will be zero." Ames and Gold added:
"Without studies of the mechanisms of carcinogenesis, the fact that a chemical is a carcinogen at the MTD in rodents provides no information about low-dose risk to humans. We must increase research to identify more major cancer risks," Ames and Gold urged, "and to better understand the hormonal determinants of breast cancer, the viral determinants of cervical cancer, and the dietary determinants of stomach and colon cancer. In this context," they concluded, "the most important contribution that animal studies can offer is insight into carcinogenesis mechanisms and into the complex natural world in which we live."
Reference: Food Chemical News, Vol. 32, No. 27, September 3, 1990.
A couple of related things on such testing are summarized in the same newsletter Anyone who wants primary sources can click on the first link to Ames' site. On the site is a listing of his 450 publications.
Interestingly, the same newsletter had an excerpt from a publication that discussed some cattle getting sick from hay that was contaminated with hemlock, and a report on air quality at an indoor tractor pull.
I would add that persistent substances that accumulate in the environment or the tissues of animals and humans are of concern--but probably for reasons other than causing cancer. Natually occuring substances usually are broken down in a reasonable time, and many pesticides are now designed to do so as well.
I get some of my fruits and vegetables from an "organic" farm and from a farmer's market. Not because of the pesticides. Because they still grow stuff that tastes good and isn't bred primarily to endure being shipped in a box or stay on the shelf forever. Yeah, the new-fangled produce often looks better or is without blemishes. But it doesn't taste as good.
