00:00:00 I'm Bruce Ames and I'd like to tell you about how scientists learn about what's causing

00:00:17 cancer. I'd like to tell you that the world is full of carcinogens. I'd like to tell you

00:00:22 why there's lots of evidence that in fact life expectancy is going to continue to get

00:00:26 longer and we're going to be able to prevent a lot of cancer. So this is a slide from the

00:00:32 American Cancer Society on cancer death rates by sight in the U.S. over the last 50 years.

00:00:37 This is 1930, 1980, and so we can see what's happening to cancer rates in the U.S. And

00:00:44 epidemiologists study this sort of thing. And the one really striking thing is this

00:00:48 line going up, and that's lung cancer. And all the evidence is overwhelmingly that that's

00:00:54 caused by smoking. And smoking is also, so smoking is causing 30% of the cancer in the

00:00:59 United States, plus 25% of the heart disease. All the cancer, it's other cancers besides

00:01:05 lung cancer. And so, and that's been pinned down in dozens of ways. So if there's one

00:01:09 thing sure in this field, it's that smoking is the big killer out there. It's eight years

00:01:13 off your life if you're two pack a day smoking. Then the other striking thing is that stomach

00:01:18 cancer, which is this line, used to be the leading cancer in the United States back in

00:01:22 1930. You can see where smoking was. And now it's been going down and down and down.

00:01:29 And we don't exactly know why the cause is. There's some ideas because the Japanese are

00:01:34 getting some clues as to what's causing stomach cancer in Japan, and that's the leading cause

00:01:38 of cancer in Japan. But I'll talk about that later. Then uterine cancer has been coming

00:01:42 down for years, and liver cancer has been coming down for years. And then if you look

00:01:46 at the other major cancers, breast cancer really hasn't changed much in 50 years. Colon

00:01:50 and erectile cancer really hasn't changed too much in 50 years. Neither has prostate

00:01:54 cancer. And of the minor types of cancer, melanomas are going up a little bit, and that's

00:02:00 thought to be mostly due to extra sunshine. And then if you are going up a little bit

00:02:04 or down a little bit, there's really not very much change. So the conclusions that epidemiologists

00:02:09 have reached is that if we're looking for causative cancer, whatever's causing breast,

00:02:13 colon, and prostate, it's been around for a long time. And that lung cancer is pinned

00:02:20 down, it's overwhelmingly due to smoking, and that we need to come up with an explanation

00:02:25 of why stomach cancer and uterine cancer and liver cancer are going down. Now, epidemiologists

00:02:31 also can look at cancer in different groups of people. The Mormons and the Seventh-day

00:02:35 Adventists have a lot, live longer and have less cancer than the rest of Americans. One

00:02:39 can look at their lifestyles, they don't smoke, they don't drink, their diet is different,

00:02:43 and come to various conclusions about what's causing cancer. And one can also look at cancer

00:02:47 in different countries, and there's been a lot of work along that line. So for example,

00:02:50 this is a plot of total dietary fat intake versus breast cancer in women. And if you

00:02:55 do colon cancer, you get a fairly similar kind of plot, because both breast and colon

00:03:00 have been associated with fat intake. So the U.S., Netherlands, Denmark, New Zealand, U.S.,

00:03:05 Switzerland are up here, and Thailand, El Salvador, Ceylon, Philippines are down here.

00:03:11 Now, that doesn't mean that fat is causing breast cancer, and association doesn't necessarily

00:03:16 mean it's causal. Some people say, well you could plot, it's just GNP, and you could plot

00:03:21 television sets, and you get the same plot, and we don't think the television sets are

00:03:24 causing cancer. But it's probably not television sets, Japan and Taiwan are down here. But

00:03:29 in fact, the evidence on fat and colon cancer is really stronger than the evidence on fat

00:03:36 and breast cancer. But what we do know is that Japanese have very low colon and breast

00:03:40 cancer rates, that the Americans have very high rates, that Japanese have very high stomach

00:03:45 cancer rates, that Americans have very low rates, that Japanese Americans become like

00:03:49 Americans. Their colon and breast cancer rate goes up, and their stomach cancer rate goes

00:03:53 down. The conclusion that there's something in the Japanese diet that either prevents

00:03:59 or colon and breast cancer or there's something in the American diet that causing it or there

00:04:03 is something in the American diet that's preventing stomach cancer or something in the Japanese

00:04:07 diet that's causing it. And hopefully we can prevent all of that, and so that's the hope

00:04:11 that maybe up to 70 or 80 percent of cancer might be preventable because of these differences

00:04:17 in different groups of people in different countries. Most of the clues were pointing

00:04:21 to diet and lifestyle, and of course smoking, because the types of cancer that we're looking

00:04:27 at have been around a long time, and there isn't any evidence that it's chemicals in

00:04:31 the modern world that are causing all of this. But in any case, epidemiologists are studying

00:04:35 all of this. So then what about rats? So this says my main fear used to be cats, now it's

00:04:41 carcinogens. So, well, the reason we're testing things, epidemiologists tend to be very suspicious

00:04:48 of rats. They say they're real human diseases, we'll study it, and humans look in different

00:04:51 people and try and get some clues as to what might be causing it. On the other hand, toxicologists

00:04:56 say, well, rats aren't really that bad, and you can, we know that workers in the aniline

00:05:02 dye industry last century, they were using beta naphthalene, a high percentage of the

00:05:07 workers got cancer 30 years later, or the workers with amino biphenyl. We know specific

00:05:11 industrial chemicals can cause cancer, why don't we test the things first in rats and

00:05:15 mice and try and prevent that? And I think that's a very reasonable idea, and the fact

00:05:19 that something comes out as a carcinogen in a rat or a mouse, I think is a reasonable,

00:05:24 there's a reasonable chance it'll be a carcinogen in people. But on the other hand, I think

00:05:28 we've completely gone overboard in interpreting rat and mouse studies. So I'd like to say

00:05:34 why I think that, but not that rats and mice aren't a way to turn up carcinogens, but concluding

00:05:41 that what we're testing in rats and mice are the carcinogens causing cancer in people is

00:05:45 another conclusion, because what we're testing in rats and mice are high volume industrial

00:05:49 chemicals, about half of them have come out as carcinogens, but that doesn't mean that

00:05:54 high volume industrial chemicals are causing cancer in the world. It may be causing cancer

00:05:58 in some workers, but it doesn't mean it's causing cancer in the world. And so a lot depends

00:06:02 on what we're testing, and we're testing a very narrow group of all the chemicals in

00:06:06 the world, because the whole world is made up of chemicals, we're made up of chemicals,

00:06:10 plants are made up of chemicals, and the natural chemicals they've tested in rats and mice,

00:06:14 about half of those have come out as carcinogens, and that makes one think a little bit, what's

00:06:20 truly representative of the chemicals in the world, and that's what I'd like to tell you,

00:06:23 is I think that animal cancer tests aren't very representative of the chemicals in the

00:06:27 world, among other things. Now the other thing is we're testing these chemicals at

00:06:31 maximum tolerated dose in rats and mice, which is the dose right under the toxic dose, and

00:06:37 the reason, there are reasons for doing that, but is this somehow biasing the test, and

00:06:41 I think it is, but we'll discuss that later, and I think the reasons for doing it were

00:06:45 good, but still I think we're over-interpreting the results we're getting out.

00:06:52 Now then there's another way of looking at the problem, and that's one we were involved

00:06:55 with for many years, and these are so-called short-term tests. I got started in this business

00:07:00 because I was reading too many labels on potato chip packages and wondering about all the

00:07:03 chemicals coming into the world, and being half a geneticist and sort of a molecular

00:07:07 biologist, biochemist, and we were mutating bacteria all the time to change the regulatory

00:07:12 mechanisms, and I started thinking, well gee, if mutagens started coming to diet, that wouldn't

00:07:17 be a good thing, maybe we should have a good test system for testing mutagens, and since

00:07:21 bacteria, you can put a billion of them on a petri plate and see if any of them are mutated,

00:07:25 it was easy to work up a system for doing that, and we spent about 10 or 15 years developing

00:07:30 a test system in bacteria for picking up mutagens, and during the course of this, I became very

00:07:34 interested in the connection between carcinogens and mutagens, because a carcinogen is a chemical

00:07:39 that gives more cancer than usual in a rat or in a person, and a mutagen is something

00:07:44 that damages the genes, the DNA, but an old idea of how chemicals cause cancer was that

00:07:49 they were mutating cells, and the cells would grow when they weren't supposed to, and cause

00:07:52 a tumor, you cut yourself, the cells grow, and you heal up the wound, and then stop growing,

00:07:58 so every cell is programmed when to grow and when not to grow, and the early idea was well

00:08:02 maybe carcinogens were mutagens, and were causing somatic mutation, and that was how

00:08:06 they were working, and I think it's a very reasonable idea, and I think in fact more

00:08:10 and more there's evidence for it, but for a long time people were somewhat skeptical

00:08:15 of that, because many of the important carcinogens were not showing up as mutagens, the benzopyrenes

00:08:19 and the beta-naphthalamines were not mutagens, and so then people said well maybe the somatic

00:08:23 mutation theory isn't right, but then the Millers and Boylan and many workers in chemical

00:08:29 carcinogenesis started showing well chemicals get metabolized by the liver and other organs,

00:08:35 and sometimes it can be 50 metabolites of a chemical, and maybe those are the true carcinogens,

00:08:39 and in fact they show the active form of beta-naphthalamine or the active form of benzopyrene, and in

00:08:44 fact those turned out to be mutagens, and so because we were working on this test for

00:08:48 mutagenicity, we took a rat and took out a rat liver and ground up the rat liver and

00:08:52 put it on our petri plates as kind of a first approximation of a rat, and the liver converts

00:08:57 the benzopyrene or aflatoxin or whatever to whatever the liver is going to convert it

00:09:00 to, many of those forms are mutagens, they mutate the bacteria and you count colonies

00:09:04 on the plate, and basically in a slightly simplified way that's what our test was about,

00:09:09 and other people developed other tests for mutagenicity, well ours was simple and easy

00:09:13 to do, and we and others showed that over 80% of the classical carcinogens came out

00:09:18 as mutagens, and so then all the industries in the world started using this test system

00:09:22 because it was easy to do and cheap, where an animal cancer test costs $500,000 and takes

00:09:27 two or three years, so it's really impractical to, if you have a hundred chemicals that you're

00:09:32 interested to develop a new drug, it's impractical to do a cancer test on all hundred chemicals,

00:09:36 and this way people could do mutagenicity tests, throw out bad ones early on, didn't

00:09:40 cost them anything, and then when they got to the end, their hope was that there'd be

00:09:44 less of a chance of that substance being nasty. So then people have been doing, using our

00:09:51 test and other tests for 15 years or so now, what have they learned? Are they getting a

00:09:55 different message in an animal cancer test? And I think the answer is yes, they're getting

00:09:58 a very different message in animal cancer, because it's so cheap to test things, in animal

00:10:03 cancer tests only maybe a hundred chemicals are tested a year, 100 or 200, in the whole

00:10:08 world because it's so expensive, and so where mutagenicity tests, there are 3,000 laboratories

00:10:13 doing our test for example, and they're testing everything, from cups of coffee to outside

00:10:18 of hamburgers, and they're finding mutagens everywhere. Okay, so that gets one shaken

00:10:24 up a little bit, what, does that mean the world is full of mutagens? And the answer

00:10:27 is yes, the world is full of mutagens. So for example, Sugimura in Japan was watching

00:10:33 his wife cook some fish on a hibachi one day, a little charcoal broiler, and he was using

00:10:38 our test system, and we had just shown cigarette smoke was full of mutagens, so he scraped

00:10:43 the surface of the fish, and tested it in our test system, it was just horribly mutagenic,

00:10:46 so then he said what's going on, he heated up carbohydrate, he heated up protein, he

00:10:50 found when you heat up protein, you get a tremendous amount of mutagenic activity, so

00:10:54 then he started heating up amino acids, heating up protein, isolating the chemicals, purifying

00:10:59 them that were the mutagens in there, and he isolated a dozen different chemicals, and

00:11:02 there are many heterocyclic amines of various sorts that you get when you cook protein,

00:11:08 and he isolated these chemicals, tested them in rats and mice, and now he's tested nine

00:11:11 of them, and all nine are carcinogens in rats and mice. Okay, so that says every time you

00:11:15 fry your hamburger, you're making carcinogens. And then other people have looked on the outside

00:11:20 of the nice brown color on your French bread, that's full of mutagens, Sugimura looked in

00:11:24 a cup of coffee and isolated the main mutagen, methylglyoxal, and now he's shown that that's

00:11:28 a carcinogen, a few thousand micrograms in a cup of coffee, plus another thousand or

00:11:32 so of hydrogen peroxide, which is a known carcinogen and mutagen. So all burnt material

00:11:37 then has mutagens and carcinogens, so you drive your car and you're pouring carcinogen

00:11:40 out of the car exhaust, you put a log on the fire, you're pouring carcinogen up your chimney,

00:11:44 so then we have to say wait a second, what's important and what's not important, because

00:11:48 you can't eliminate all burnt material in the world, and you wouldn't want to, so, and

00:11:53 that's where I think we're coming to on all of this, what's important. Now, you can do

00:11:57 a quick calculation, so everybody's worried about air pollution, but you can do a quick

00:12:02 calculation that a smoker gets 20 milligrams of tar in a cigarette times 40 cigarettes

00:12:07 a day is 800 milligrams, so it's about this much burnt material a day coating your lungs.

00:12:13 How many smokers here? Not very many, right. So, but how much Los Angeles air do you need

00:12:20 to get that much burnt material? Well it turns out it's about a year's worth. So air pollution

00:12:25 is nasty, we should regulate it and all of that, but it's just not very much there relative

00:12:29 to smoking. So in fact, indoor air is worse than outdoor air, partly because one smoker

00:12:33 can pollute a whole room this size with a cigarette, and so that means that if you're

00:12:38 going to do epidemiology on lung cancer and air pollution, you have to be awfully careful,

00:12:44 because there's that big thing out there and that's cigarette smoking. So for example in

00:12:47 Contra Costa County near here, a lot of refineries, there's some extra lung cancer, everybody

00:12:52 said, ah, it's due to the refineries, the years in the newspaper, it's those damn refineries,

00:12:56 but it never made much toxicological sense, because one, the Contra Costa air isn't that

00:13:01 polluted compared to all the other cities in the United States, and this is the wind

00:13:05 blowing off the bay, and two, you have to control for smoking, and in fact it turns

00:13:09 out that blue collar workers smoke a lot more than the rest of Californians, and blue collar

00:13:13 workers tend to live around refineries, so in fact in the end, it's probably due to extra

00:13:18 blue collar workers around there, you can't say for 100% sure, but I think that's going

00:13:23 to be the explanation. So that means that epidemiology is very tricky, it has to be

00:13:28 toxicologically reasonable, the fact that two things are together doesn't mean one caused

00:13:32 the other, the number of storks in Europe has been going down for years, the birth rate's

00:13:35 been going down for years, doesn't mean storks bring babies, so you can find a part per billion

00:13:40 of something in the water and you can find a cancer or birth defect, it doesn't mean

00:13:43 there's any connection, because it's a tribute to modern technology that you can measure

00:13:47 a part per billion, but it's nothing you really want to worry about. A few years ago

00:13:52 E.D. Emeseki and I decided to look at cigarette smokers, and we looked at all the smokers

00:14:02 in the biochemistry department from mutagenicity, looked in the urine, and that's on the right

00:14:06 are all the smokers in the biochemistry department, actually there are very few smokers in the

00:14:09 biochemistry department anymore, and on the left are all the people in my laboratory.

00:14:14 So you can tell smokers from non-smokers. So now I'd like to talk about toxic chemicals

00:14:20 in plants, and this isn't chemical plants, it's green plants, and that shakes everybody

00:14:24 up, nature's benign, we all know that, except how do you think plants survive in nature?

00:14:29 There are millions of insects ready to eat plants and predators, and plants can't run

00:14:33 away, they don't have teeth, and so all of plant evolution is chemical warfare, every

00:14:39 plant is 5 or 10 percent of its weight in toxic chemicals, and these are nature's pesticides,

00:14:44 and the reason is that's how evolution works, these plants have to protect themselves, I

00:14:47 mean we know about strychnine and all sorts of things in plants, but every plant, your

00:14:51 lettuce, your tomato, your potato, is 5 or 10 percent of its weight in toxic chemicals,

00:14:55 and every plant has a dozen different ones, and the organic chemists have isolated hundreds

00:14:59 of thousands of these over the years, they're all in the literature, and they're still isolating

00:15:02 new ones all the time, we've done practically very little toxicology on this, and the minute

00:15:07 you start looking, people are finding all kinds of mutagens and carcinogens, and as

00:15:12 I say, I think the percentage of carcinogens coming out from natural chemicals is about

00:15:16 half, not that different from the percentage of man-made chemicals. Hydrazines are a well-known

00:15:21 class of man-made carcinogens, 52 different hydrazines have been shown to be carcinogens,

00:15:26 rocket fuel is dimethylhydrazine, that's a carcinogen, but Bella Topp, who was doing

00:15:31 a lot of studies on hydrazine carcinogenesis, read a paper somewhere that mushrooms had

00:15:35 hydrazines, so he started looking at all the hydrazines in mushrooms, and mushrooms are

00:15:39 a whole zoo of different hydrazines, so gyromitra, which is false morel, which is widely eaten

00:15:44 in Europe and the U.S., has 11 different hydrazines, and 5 or 6 now have been shown to be mutagens

00:15:49 and carcinogens, and then the common storm mushroom, Agaricus bisperus, has all kinds

00:15:54 of interesting hydrazines, the main one is something called agaritine, it's 300 milligrams

00:15:58 per 100 grams of mushrooms, so these are there in large amounts, that was negative in one

00:16:02 test, but several of its metabolites have been shown to be potent carcinogens, particularly

00:16:06 diazonium metabolite, which is a very good mutagen and carcinogen, and then the parahydrazine

00:16:12 of benzoic acid, which is an analog of pyrimidobenzoic acid, there's some evidence that that's a

00:16:17 carcinogen, and Topp now has fed raw mushrooms to mice and gotten lots of tumors of different

00:16:22 sizes, so mushrooms have carcinogens, now probably most of this is destroyed on cooking,

00:16:28 but should you really worry about a raw mushroom, I'll get to that later, then alloisothiocyanate

00:16:34 is the main flavor ingredient, oil of mustard and horseradish, and that's been shown to

00:16:38 be a carcinogen, piperine is 10% of the weight of black pepper, and black, somebody took

00:16:44 an extract of black pepper, put it on the skin of rodents, and they got lots of tumors,

00:16:48 and black piperine is closely related in structure to saffron and estrogel, which are two known

00:16:53 plant pesticides that are natural pesticides that are known liver carcinogens, and saffron

00:16:59 and estrogel are in basil and oil of sassafras and lots of spices you eat, in fact they used

00:17:04 to make root beer out of oil of sassafras, but it's 75% in saffron, and so they eventually

00:17:09 banned natural root beer because it was too dangerous and went over to synthetic root

00:17:13 beer, which is probably safer for you, but in any case these things are around in a number

00:17:18 of herbs, then solanine and chaconine are interesting, and I mention these not because

00:17:23 they're carcinogens, but because nobody's tested them, so they're cholinesterase inhibitors

00:17:28 and they're present in potatoes, so you have to get into the mind of thinking that everything

00:17:32 has to have toxic chemicals, because that's how plants have to survive, so plants, nature's

00:17:37 pesticides are there, and every plant has to have these things, and so solanine and

00:17:43 chaconine are present in potatoes and they're cholinesterase inhibitors, well you know the

00:17:47 main man-made pesticides are organophosphates now that we've gone past the DDTs and compounds

00:17:53 like that, malathion for example, so malathion is one of the main organophosphate pesticides,

00:17:58 it's a cholinesterase inhibitor, and I was on the governor's medfly committee when there

00:18:02 was a medfly infestation in California and the helicopters were flying over Palo Alto

00:18:06 dropping malathion, everybody was scared, stiff pesticides, helicopters, and they were

00:18:11 really afraid, now the real danger was from a helicopter crashing into your house or falling

00:18:14 off a ladder when you're stripping your apricot trees, but it was a national emergency because

00:18:19 of the medfly, but they were dropping about a milligram of malathion per square foot of

00:18:23 your front lawn, so if you rolled over naked on your front lawn you might get a few micrograms

00:18:27 of malathion into you, well malathion was tested at enormous levels in rats and mice

00:18:33 and was negative, and every time you eat a potato you get 15,000 micrograms of cholinesterase

00:18:39 inhibitors, that's solanine and chaconine, just from eating a potato, and nobody's ever

00:18:44 bothered testing those, doing much toxicology on those, even though human blood is full

00:18:49 of it, every one of you has it in your blood because you all eat potatoes, and not only

00:18:53 that people have, kids have died from eating meals of potatoes, now that's a bit shocking,

00:18:58 but that's green potatoes, when a potato gets left out in the light it turns green, that's

00:19:03 chlorophyll, but the potato is designed so that when it's uncovered it makes lots more

00:19:09 solanine and chaconine because insects, it's more susceptible to insects when it's out

00:19:13 of the ground, and so the potato makes lots more solanine and chaconine if you eat a meal

00:19:18 of green potatoes it'll kill you if you're a kid, and that's the recorded cases of that,

00:19:22 and in fact plant breeders now all over the world are breeding plants to be insect resistant,

00:19:27 which is because everybody's afraid of man-made pesticides, but all of course they're doing

00:19:30 is raising the level of all these natural things, in fact they bred a potato that was

00:19:34 marvelously insect resistant, they introduced it and they had to withdraw it right away

00:19:37 because everybody got ill eating the potato, there's just little variations in the soil

00:19:41 changed the solanine and chaconine levels and it was right at the toxic level, so anyway

00:19:46 these haven't been tested but I'm just trying to give this to give some idea of what the

00:19:51 world is really like, then solanine derivatives are light activated carcinogens at present,

00:19:55 parsnip, oil of bergamot, celery, they're quite widespread, celery will make a hundred

00:20:00 times more of these if it's damaged by fungus, so there's an occupational disease in California

00:20:06 of the celery pickers getting a terrible rash on them and that's because they're getting

00:20:10 this carcinogen all over the skin from the damaged celery and then the light activates

00:20:14 it and you get a terrible rash, and so these are quite good mutagens too if you shine a

00:20:19 little light on the bacteria when you put sorrel into it, gospels and cottonseed oil,

00:20:24 bison and dye bison are in favor, beans, perolazine and alkaloids are really nasty carcinogens

00:20:28 that are in comfrey tea, so again we're going back to nature, everybody's drinking all these

00:20:32 herb teas, the biggest seller is comfrey tea, but comfrey tea is well known to have all

00:20:36 these carcinogens, again nobody notifies the health food stores, if people think it's natural

00:20:40 it's fine, and people in Mexico have wrecked their lung and their liver from eating strong

00:20:44 teas with perolazine and alkaloids, so it's the loss of case in literature, people dying

00:20:48 from too much of these perolazine and alkaloids, sesquiterpene, lactones in lettuce, quinones

00:20:54 in plants, theobromine, cannabinine is interesting because what could be more natural than putting

00:21:00 alfalfa sprouts on a sandwich, well it turns out alfalfa sprouts are really nasty things

00:21:06 because if you feed alfalfa sprouts to monkeys they come down with lupus, which is an autoimmune

00:21:10 disease, well it turns out that alfalfa sprouts are 2% of the weight in cannabinine, and cannabinine

00:21:16 is an arginine analog, so it looks just like the amino acid arginine except it has an oxygen

00:21:20 in the side chain instead of a carbon, and it's a perfect dead ringer for arginine, so

00:21:24 it sneaks in through transport systems, it sneaks in to proteins, so you make all this

00:21:29 junk protein with cannabinine in it instead of arginine, and that's known in bacteria

00:21:32 and animal cells, and so you can feed cannabinine to monkeys and get them to come down with

00:21:36 lupus, so again what's happening to people eating it, I'm not sure, but the world is

00:21:41 full of these things, and so then I added up how much pesticide residues do we eat in

00:21:47 a day, and food and drug has done a big analysis of all the pesticides in American food and

00:21:51 added it all up, and so it's about 150 micrograms a day of pesticide residues, just for balance

00:21:59 there are about 4000 micrograms of known carcinogens in a cup of coffee, so I'm not saying a cup

00:22:04 of coffee is dangerous, it's just to give you an amount, a feeling of amounts, and of

00:22:07 that 150 micrograms, at least 100 micrograms of things like malathion that have been negative

00:22:12 in cancer tests, so at the most we're getting 50 micrograms of carcinogen a day, and as

00:22:16 I'll show you later, I think that's very tiny relative to the background of carcinogen.

00:22:21 We're eating 10,000 times more of nature's pesticides a day than man-made pesticides,

00:22:26 and practically no toxicology has been done on these things, and I'm convinced if they

00:22:30 run all these things through, they'll find just as many carcinogens as they do among

00:22:33 the man-made pesticides, but that remains to be seen.

00:22:38 Aflatoxin, moles make all kinds of carcinogens, and 300 mole toxins have been discovered,

00:22:46 and many of these that have been tested have come out as carcinogens, aflatoxin stereosomatic

00:22:50 system, again a high percentage of the mole toxins that have been tested have come out

00:22:53 as carcinogens, some of these are very potent, and aflatoxin is present in little bits in

00:22:58 all the peanut butter we eat, and in the tropics you get lots of it, and with modern

00:23:02 food processing in America you don't get that much.

00:23:05 How do we protect ourselves against all this? Well animals have figured out all kinds of

00:23:08 ways to protect ourselves against carcinogens, we have, one way is we're disposable, a whole

00:23:15 lining of our digestive system is thrown away every day, the lining of your skin is thrown

00:23:19 away, the surface of your eye, anything exposed to the outside world, those cells are thrown

00:23:23 away, so the way your colon and intestine work is that all these villi, the crypt cells

00:23:29 are down here, and they're the stem cells that give rise to all these other cells, they

00:23:33 divide unidirectionally, the daughter cells move up, and then they get sloughed off, so

00:23:38 every day you're shedding the surface of your whole digestive system every day, because

00:23:42 you're eating all kinds of mutagens and carcinogens, and so in this way even if a cell gets mutated

00:23:47 it can't become a cancer cell because it's thrown away, so that's a good general defense

00:23:51 against everything, man-made or natural chemicals, plus there's a mucin layer that acts as a

00:23:56 protection, then we have all kinds of general detoxifying enzymes in our liver, we have

00:24:00 DNA repair systems, so we have layers and layers of defenses, lots of these are inducible

00:24:04 defenses, so we're designed to live in a world of carcinogens, as far as dietary advice goes,

00:24:11 this says if you want fiber madame I suggest you eat the menu, and the reason I put this

00:24:15 in is people are getting a few clues as to what the dietary causes of colon cancer or

00:24:22 stomach cancer might be, in stomach cancer in Japan, the risk factors seem to be coming

00:24:28 out as very high nitrate in the diet, so nitrate forms powerful nitrosamine carcinogens, if

00:24:35 you don't have vitamin C around, and so Americans eat lots of vitamin C, Japanese eat relatively

00:24:41 little, because they're not buying enough California oranges, so, and they have very

00:24:45 high nitrate because they eat a lot of root vegetables with nitrate in it, and so that's

00:24:48 thought to be at least a possible cause of the stomach cancer in Japan, one last factor

00:24:53 is high salt, now salt isn't your average carcinogen, but in fact salt seems to be an

00:24:58 important promoting factor in cancer of the stomach, and so high salt damages the cells

00:25:04 and causes a lot of cell proliferation, that seems to be very important, maybe even the

00:25:07 most important factor, the Japanese get a lot of salt in their soy sauce and pickled

00:25:11 vegetables, and American salt consumption is relatively low, so, and America had a lot

00:25:16 of stomach cancer 50 years ago, but then we were salting our foods a lot more, we were

00:25:19 getting much less vitamin C before refrigerated boxcars came in, and we were getting much

00:25:24 more nitrate, so anyway, but that isn't pinned down the way smoking and cancer, and lung

00:25:29 cancer is pinned down, but at least it's a general hypothesis, and then what about fiber

00:25:34 and colon cancer, with colon cancer the protective factors seem to be fiber and calcium perhaps,

00:25:41 and the risk factor may be high fat, there's a fellow in Canada, Bob Bruce, who has an

00:25:46 idea that it's the fatty acid, the free fatty acids in the colon act as a detergent and

00:25:51 kill cells and cause cell proliferation, and the calcium sequesters the free fatty acid

00:25:56 and prevents it from doing that, and the fiber also helps, so there, again the protective

00:26:00 factors might be calcium and fiber, the risk factors might be high fat, and it's slowly

00:26:06 being sorted out, we don't know whether that theory is true, people are having some ideas

00:26:09 and testing it in various ways, we're not sure that what I told you about stomach cancer

00:26:13 is true, though we are sure about smoking and lung cancer, but the ideas are coming

00:26:18 fast, people are getting ideas, they're testing them, they're testing them in animals, they're

00:26:21 doing more epidemiology, and I think one after another these major cancers we're going to

00:26:25 figure out the causes, there'll be combinations of things, it may be lack of something or

00:26:29 too much salt or things like that, but it will be worked out, and high fat we already

00:26:34 know is very bad for heart disease, high saturated fat, and so just for heart disease you should

00:26:41 lower your saturated fat and it might help on your colon cancer as well, and high salt

00:26:44 is bad for heart disease too, so maybe overdoing the salt isn't a good idea.

00:26:51 So now I'd like to shift into another area, and that is to discuss aging and cancer, because

00:26:56 I think this is quite relevant, it again gets to the idea about nature and is it benign

00:27:01 and all of that, so if you look at cancer in rats, this gives cumulative cancer risk

00:27:06 versus age, so a rat lives about two years, and by the end of its lifespan 30% of the

00:27:12 rats have cancer, this is just on ordinary food, not giving them any carcinogens, so

00:27:16 just living 30% of the rats get cancer, but as you can see by one year very few of them

00:27:21 have, by two years it's up here, so it's something like the fourth power of age, now people

00:27:26 also get cancer with about the fourth power of age, but human life expectancy keeps on

00:27:30 getting longer, so we're moving up this curve, which means that the more total people getting

00:27:35 cancer, and that's part of the fear, oh there's more cancer around, well there is more cancer

00:27:39 around because if you looked at groups of 40 year olds you wouldn't see any cancer,

00:27:42 and at the turn of the century people were dying at age 40, but what epidemiologists

00:27:46 do is they always age correct, they look at a group of 40 year olds, 50 year olds, 60

00:27:50 year olds, and ask is cancer increasing, as I say it's not except for lung cancer,

00:27:56 but the total amount of cancer is going up because of this strong dependence on age,

00:28:01 so that says cancer, whatever is doing us in for aging might be also doing us in for

00:28:05 cancer, so cancer is some degenerative disease of old age, as is heart disease, a lot of

00:28:10 degenerative disease come up with age, so what that means is we're never going to eliminate

00:28:14 cancer, all we keep on doing is pushing it as we get life expectancy gets longer and

00:28:19 I'll give you the reasons why I think it will continue to get longer, we're moving down

00:28:23 this curve and moving up here, so there will be more total cancer, but yet we're pushing

00:28:26 it further down, so that if you stop, everybody stops smoking, smoking is 8 years off your

00:28:31 life, everybody would live on the average 8 years longer, but you'd still, some of those

00:28:36 people might die of another type of cancer later, heart disease or whatever, so in any

00:28:42 case this raises the question, what's doing us in inside our own body, what's in normal

00:28:47 metabolism is causing cancer, what's causing aging, and that's a big question, but I think

00:28:51 again scientists are moving very fast on all these fronts, so one thing that's clear is

00:28:57 that it's under evolutionary control, we've gone from here to here in roughly 60 million

00:29:02 years of evolution, we've gone from prosimians, which were short-lived creatures to long-lived

00:29:06 humans, so what happened, how do we lower, a rat has enormously higher cancer rate than

00:29:10 a human, by age 2, 30% of the rats are getting cancer and it takes people up to the 70's

00:29:17 and 80's for 30% of us to get cancer with this 4th power figure, so people interested

00:29:22 in life span know that it's somehow related to metabolic rate, a rat has a very high metabolic

00:29:27 rate compared to a human, so 7 times, so a rat has to eat a lot, breathe in a lot more

00:29:33 oxygen, eat a lot more food, all its metabolism is racing around compared to a human, so one

00:29:38 way you can lengthen your life span, you just cut down your metabolic rate, and one way

00:29:42 you can do that is just by getting larger, because a larger creature is better insulated,

00:29:48 doesn't need to make as much heat, and therefore can have a lower metabolism, so at least that's

00:29:53 one factor in all of this, and so I've gotten very interested in what a normal metabolism

00:29:59 might be doing us in, and more and more I've gotten interested in oxygen, so it isn't enough

00:30:04 that all your food is full of carcinogen, oxygen is really nasty stuff, so basically

00:30:10 there are all kinds of compromises in metabolism, so evolution gets you past your reproductive

00:30:15 age and then all these compromises start coming in and doing you in, so now I'd like to switch

00:30:21 over and discuss something about risk assessment and why you can't do it, that is you can do

00:30:28 risk assessment from human numbers, radon is coming out of the ground into your houses,

00:30:33 it's the biggest source of radioactivity in the country, you have dead uranium miners

00:30:36 from radon, you can do some numbers and get a rough idea of how many cases of cancer it

00:30:42 will cause, 10,000 cases of cancer, they think it's the largest cause of lung cancer other

00:30:46 than smoking in the country, so people can do, that's real risk assessment, but taking

00:30:53 a number from a rat and extrapolating it three miles down the road to figure out what the

00:30:58 risk is for a low dose to a people, you don't know how to do it, and the reason is we're

00:31:02 testing all these chemicals at high doses in rats and we don't know what low doses will

00:31:06 do, and I want to give you some reasons why there's a big cloud over that, because we

00:31:12 don't know what's happening, we don't understand the mechanism, particularly for chemicals

00:31:15 that are not, that are coming out as carcinogens that are not mutagen, the trichloroethylene

00:31:20 from the DDT's and things like that, okay, so this just shows, we've done a big database

00:31:26 of taking all the animal cancer tests in the world, and this is the work of Lois Gold and

00:31:29 Kim Hooper and other people here at Berkeley, and we've taken all the cancer tests in the

00:31:33 world, put the information into a computer, and calculated potency of the carcinogens,

00:31:38 so we have 3500 experiments in about a thousand chemicals, so we've cleaned out the world's

00:31:43 literature on thorough animal cancer testing and do some calculations, and in our database

00:31:49 there were 303 chemicals that were tested in both rats and mice, 58% of these are positive,

00:31:54 so again people are saying carcinogens are rare, they're not rare, now it may be that

00:31:57 we've been testing more suspicious chemicals, but as I say, when we tried to break this

00:32:01 down into natural things and man-made things, it was about half for both, and if you look

00:32:06 at just the metals, lead, iron, cadmium, chromium, there are lots of the ordinary metals of carcinogens,

00:32:13 so it isn't that the world's natural things aren't carcinogens and man-made ones, our

00:32:17 asbestos is all natural, so what we've done is done an idea of the potency, the potency

00:32:23 we call the TD50, which is like an LD50, it's what's the dose given every day of the

00:32:28 lifetime to the animal to give half the animal's cancer, now all these tests are done at the

00:32:33 toxic dose, they find the level that will kill the animal and just back off a little

00:32:36 bit, so it's the maximum tolerated dose for the lifetime, and so, and then you can say

00:32:41 well aflatoxin is about a microgram per kilo per day for every day of the lifetime to give

00:32:46 half the animal's cancer, ethylene dibromide is a thousand times weaker, that's a milligram

00:32:50 per kilo per day for every day of the lifetime, and then something like trichloroethylene

00:32:53 is a thousand times weaker than that, so between something down to 10 grams, and the most interesting

00:33:00 carcinogen actually is about 10 grams per kilo per day, and I'll tell you about that

00:33:04 later, and it's alcohol, and that's the weakest carcinogen in our database, and the strongest

00:33:09 carcinogen in our database is dioxin, which is down here around 100 nanograms, so that's

00:33:14 eight orders of magnitude, so you have to know something about how potent it is in rats,

00:33:19 if you're going to do any kind of possible hazard, because, and you want to know what

00:33:23 the human exposure is, and that's what we've been doing, is trying to estimate what is

00:33:27 the human exposure on chloroform in your drinking water, or aflatoxin in your peanut butter,

00:33:32 or whatever, and what's, put a fudge factor into the potency, and then get a possible

00:33:37 hazard, but this isn't risk, because again we're talking about low dose extrapolation,

00:33:41 we don't know whether we can do low dose extrapolation, there's a threshold, it doesn't make any sense

00:33:46 to do a low dose extrapolation, and in fact I think there probably will be, that everything

00:33:52 won't be linear extrapolation, and now the other thing is the mechanism, so I think most

00:33:56 people agree that mutation is one aspect of carcinogenesis, but you need more than that,

00:34:01 you need something called promotion, and promotion is a cellular thing, so even though you have

00:34:07 a mutated cell, all its neighboring cells are telling it don't grow, because cells are

00:34:11 communicating through gap junctions in the liver, all the cells are in there, and they're

00:34:16 all telling each other not to grow, and you can mutate that cell, make an oncogene, and

00:34:20 that cell won't grow until there's a cluster of cells telling each other to grow, rather

00:34:25 than not to grow, and the way you can get that is by taking out half the liver and having

00:34:29 a lot of liver regeneration, then a tiny dose of carcinogen gives you lots of tumors, but

00:34:33 if you don't do that, you don't see any tumors, if the liver is just normal, sorry, and so

00:34:38 I think that the promotion is going to end up being all kinds of things that are telling

00:34:42 cells to grow in one way or another, so you can get the cell to get a clone, and one way

00:34:48 you can do it is just kill a lot of cells, and then you get regeneration, or hormones

00:34:53 can give you cellular proliferation, or something that interferes with gap junctions, anyway

00:34:58 we're working all that out, none of these things are things that you'd expect to give

00:35:01 problems at low doses, because all those kinds of mechanisms I think are going to be threshold

00:35:05 type of mechanisms, and you're going to have a multiplicative effect between this and that,

00:35:09 so for example liver cancer in the world is, seems to be, there's lots of aflatoxin

00:35:14 in the tropics, but people now think it's not just the aflatoxin, it's aflatoxin plus

00:35:18 hepatitis B virus, because hepatitis B virus is getting into your liver and causing a lot

00:35:22 of cell killing, you're getting constant chronic irritation, and it's the aflatoxin plus that

00:35:26 that gives rise to liver cancer, and that's true in China, in Africa, so it may be two

00:35:31 things, one you need more than a mutation, and so, and what are we doing when we do the

00:35:36 maximum tolerated dose, you're giving a level that'll, just below the level that'll kill

00:35:41 the animal, and you're doing it every day of the lifetime, so I'm very worried about

00:35:45 chronic inflammation, and that kind of thing, being a serious cause of cancer, and even

00:35:50 for human cancer, maybe when you go out in the sunshine, the important thing is not just

00:35:54 a little bit of sunshine, but when you burn yourself and get really red, and when you

00:35:58 overdo it and get cell killing and cell proliferation, so, and there's evidence in human cancer,

00:36:04 and now, when they're rigorous about maximum tolerated dose, half the chemicals they're

00:36:07 testing are not mutants, the old classic of carcinogens, much higher percentage of mutants,

00:36:11 what does that mean, why are these chemicals that we want to worry about at high doses

00:36:15 but not at low doses, it may be, and so maybe you want to worry about a factory worker getting

00:36:19 a level in that's close to the toxic level, but you don't want to worry at all about a

00:36:23 park pavilion in the water, and I think you don't want to worry about a park pavilion

00:36:27 in the water anyway, I'll show you why, so what we've been doing, it's a little hard

00:36:32 to read, but what we've been doing is taking, I just had a review in science discussing

00:36:37 all this with Lois Gould and Renee McGowan, is we take all sorts of exposures to carcinogens,

00:36:44 put in a fudge factor for the potency in the human exposure, and express this as a percentage,

00:36:49 so this is a percentage of, we call the HERP, the human exposure rodent potency percentage,

00:36:56 so it's what percentage is the human exposure over the dose to give half the rats and mice

00:37:01 cancer, and that way it adjusts for the potency of things, so for example chloroform is in

00:37:08 all US tap water, because you chlorinate the water, and that was the big public health

00:37:12 advance of the century is chlorinating water, so you chlorinate the water, you pay for it

00:37:16 in getting 83 micrograms US average of chloroform in tap water, chloroform is a carcinogen at

00:37:22 about 100 milligrams per kilo per day, put every day of the lifetime to give half the

00:37:26 rats and mice cancer, so the amount in average US tap water is .001, and that gives you,

00:37:32 we can compare things to tap water, so a glass of tap water then would be .0025, again all

00:37:38 this is meant every day of your lifetime, that's how the rat tests are done, so now

00:37:43 Silicon Valley they closed down 35 wells, by the way tap water has little bits of lead

00:37:47 and arsenic and all sorts of other things, so the e-chloroform isn't even the main carcinogen

00:37:51 of water, but again the low levels that I don't think we should really be worrying about.

00:37:56 The Silicon Valley they closed down 35 wells, the EPA closed down them, it's been in newspapers

00:38:02 for years, Silicon Valley polluted, polluted, polluted, but in fact 33 of those wells were

00:38:07 safer than tap water, if you calculate the amount of trichloroethylene that was in there

00:38:11 compared to the amount of chloroform in US average tap water, this is well water that

00:38:14 wasn't chlorinated, and the worst well was .004, it's only a few times worse than ordinary

00:38:20 tap water, it's way under the average peanut butter sandwich, and thousands of times under

00:38:24 a beer, something like that. So then, Woburn, Massachusetts, again it's on 60 minutes in

00:38:32 the newspapers, ah that caused those birth defects and that caused the cancer, well at

00:38:35 least as far as the cancer goes it's completely non-credible because that water is safer than

00:38:39 tap water, so nobody did the elementary toxicology or weren't interested in it, because it isn't

00:38:46 a credible hypothesis, and I don't think it's a credible hypothesis for the birth defects

00:38:50 either, because the amounts are just way too low, at least what they measured in that one,

00:38:55 and you only drink a liter or two of water a day and it's pretty hard to get very much

00:38:59 of it into you, where air, you breathe in 20,000 liters of air a day, so in a factory

00:39:04 you can really get a high dose of something because you breathe a lot in air, but, so

00:39:07 in the lab, handling a little bit of carcinogen isn't much of a risk, but when you have chloroform

00:39:13 in the lab all day long and you're breathing a lot of it in, then you can get a lot into

00:39:16 you, and then pesticide residues, as I told you, the total amount is very small, and if

00:39:22 you calculate the PCBs we're getting per day, it comes out .0002, so it's equivalent of

00:39:28 a glass of water, and DDE, DDT residues are about the same thing, even if you add a hundred

00:39:33 times that level of DDT, it still comes out small relative to lots of natural things,

00:39:38 and ethylene dibromide, they banned the main fumigant in the country for .0004, so again

00:39:45 it's about a glass of water, but it's carcinogen, it's in your grain, we want to eliminate it,

00:39:49 now what the consequences of eliminating the main fumigant in the country is another matter,

00:39:53 more insects get in the grain, they bring in more mold, more mold toxins, are we going

00:39:57 to irradiate our food, nobody knows whether any of the alternatives are much worse, so,

00:40:01 but that's how we go, you hear carcinogen, you eliminate it, but with 50% of the chemicals

00:40:06 coming out as carcinogen, it's crazy to think of eliminating every carcinogen, and we'll

00:40:10 just bankrupt the country if we go after all the trivia, you have to decide what's important

00:40:14 and go after important, and there are plenty of important things out there, but a sandwich

00:40:18 is .03 based on two parts per billion of aflatoxin peanut butter, aflatoxin is so potent that

00:40:23 it comes out a pretty high number, but I'm not really worried about the average peanut

00:40:27 butter sandwich, the food and drug allows 10 times more than this, which is .3, so again

00:40:32 we're getting to be relatively high numbers compared to these pesticide ranges, very high

00:40:37 compared to pesticide ranges, but should we really worry about all these things, and that

00:40:41 you worry about it if you're really worried about low doses on everything, and I guess

00:40:44 I'm less and less worried about low doses really being important, I think it's when

00:40:48 you get close to the toxic dose that we want to worry, and then squid, when you cook anything

00:40:53 in a gas oven, you're making nitrosamines, because all that NO2 in a gas oven is making

00:40:57 nitrosamines in your food, and so you can get, if you cook some squid in a gas oven,

00:41:02 some Japanese measured .06 for dimethyl nitrosamine, but I think that's happening whenever you

00:41:06 cook anything in a gas oven, brown mustard .07 for the allyl isothiocyanate in 5 grams

00:41:13 of brown mustard, basil, a basil leaf, or this is a gram of dried leaf, is .1, so my

00:41:19 wife is Italian, she makes pesto sauce all the time with basil, so do we really want

00:41:24 to worry about that, and again I think not because the question isn't that it's natural,

00:41:31 but the question is that we're talking about doses way below the toxic dose, now maybe

00:41:36 you don't want to eat basil as the main item in your diet for all your life, but the occasional

00:41:41 basil I think isn't anything to worry about, raw mushrooms .1 for one raw mushroom, okay,

00:41:47 all of you eat raw mushrooms occasionally, again this is all based on every day of your

00:41:51 life, a root beer has saffron, if it's natural that would be .2, so that's bad enough, now

00:41:56 what about alcohol, alcohol is really one of the most interesting carcinogens, because

00:42:00 alcohol we know causes human cancer, there's hundreds of epidemiological studies showing

00:42:05 that alcohol is a risk factor for cancer of the liver, when you get cirrhosis of the liver,

00:42:10 cancer of the larynx, cancer of the esophagus, and alcohols cause cancer in rats, so what

00:42:15 more could you want, and acetaldehyde, the main metabolites cause cancer in rats, so

00:42:19 and alcohol is the leading cause of birth defects in the country, if you, women who

00:42:24 drink get fetal alcohol syndrome, so we know all about alcohol, and yet alcohol is the

00:42:30 weakest carcinogen in our database, it's about 10 grams per kilo per day to be fed

00:42:35 every day of your lifetime to give half the rats cancer, just based on the rat numbers,

00:42:38 I haven't used the human numbers, well we get 18 grams of ethyl alcohol in a beer, so

00:42:44 the problem is the dose is so enormous, even though it's very weak, so for example compare

00:42:48 trichloroethylene and alcohol, alcohol is about 10 times worse, less potent as a carcinogen

00:42:54 than trichloroethylene, but there might be a few parts per trichloroethylene, a few parts

00:43:00 per billion of trichloroethylene in the water, but a beer is 5% in alcohol, that's 50 million

00:43:04 parts per billion of alcohol in a beer, and there's a factor of 10 in the potency, so

00:43:08 right away you can see nothing is going to come close to alcohol, and in fact the numbers

00:43:12 come out about 3 for a beer, and about 5 for a glass of wine, so we're 3% of the dose to

00:43:20 give half the animals cancer, so again I'm not so much worried about a beer a day, I

00:43:25 think it's when you get enough into you to start giving your cirrhosis of the liver really

00:43:29 damage that you want to worry, and then occupational exposure, we have a separate paper coming

00:43:34 out on that, there you can get big numbers, for example in California, the ethylene dibromide

00:43:41 was the factory workers were allowed to get in an amount that was equal to the amount

00:43:46 that was giving half the rats and mice cancer on a milligram per kilo base, because they

00:43:49 were breathing it in all the time, and I testified in California, we got them to, California

00:43:54 to tighten up by over 100 fold, which was quite a much more reasonable standard, but

00:43:58 OSHA never did anything, so California was very progressive on that, but it's one thing

00:44:02 to tighten up on workers for that kind of level, it's another to worry about .0004 or

00:44:07 something like that, which is less than ordinary tap water, when there are all sorts of enormous

00:44:12 economic consequences, you ban the main fumigant in the country, so anyway, so I think they

00:44:18 should have strict rules about workers, so what's important and what's not important,

00:44:22 that's where the whole thing finally comes, I mean smoking is important, it's 30% of the

00:44:26 cancer, 25% of the heart disease, and yet the government is spending about as much money

00:44:29 to subsidize tobacco farmers as they are for all the cancer research in the country, so

00:44:33 that shows where the priorities are, but maybe, and age is important, saturated fat in your

00:44:38 diet is important, there are lots of important things out there, and if we spend all our

00:44:42 time on trivia, I think we're lost, and what about life expectancy, it's going up, this

00:44:48 is from 19, again from the turn of the century, life expectancy is going up and up and up,

00:44:52 this is women up here, this is men, a good part of the difference is actually due to

00:44:56 smoking, women started smoking only after the second world war, and it takes 20 or 30

00:45:01 years before lung cancer comes in, and now there's an epidemic of lung cancer in women,

00:45:05 so women are going to catch up on some of this difference with men, but men are starting

00:45:09 to stop smoking, so, but I think that curve is going to go up and up and up, because biology

00:45:16 is going so fast, we're learning so many things about how things work, we're going to learn

00:45:19 about mechanisms, carcinogenesis, we're going to learn about what's the cause of colon cancer

00:45:22 and breast cancer and stomach cancer, which are the main types of cancer around, and so

00:45:26 there's every expectation, if AIDS doesn't do us all in, there's every expectation that

00:45:31 the life expectancy is going up, so it's modern technology that's enabling scientists to understand

00:45:36 all this, we couldn't measure all these things in the urine if we didn't have computers and

00:45:40 all of that, so it isn't technology that's doing us in, it's technology that's giving

00:45:43 us our, the life that we have, and so the very last slide says, relax, I've come for

00:45:50 your toaster, and the point is, we shouldn't scare people about unimportant risks.

00:46:07 The distribution of this tape was supported by the Council for Chemical Research, Incorporated,

00:46:13 a non-profit organization whose primary purpose is to support and encourage basic research

00:46:20 in the chemical sciences and engineering. The council's membership consists of representatives

00:46:27 from the academic and industrial community.