Oh, Rubbish

By Jeffrey Kluger|Monday, August 01, 1994
As any archeologist--from the lowliest grad student to the loftiest Leakey--will tell you, the study of humans and their origins is often little more than the study of trash. Ordinarily we don't think of early humans as prodigious trash producers. There were no discarded magazines in Ice Age caves ("1,001 Limestone Dwelling Ideas") or discarded food packages in Olduvai Gorge ("Hungry Man Wildebeest Dinner--With Extra Apple Crisp!"). But early people did do their share of early littering. What is a priceless shard of discarded pottery but the prehistoric equivalent of the Jetsons jelly jar you threw out last week? What is the abandoned bison pelt but last year's winter coat? What is a cave painting but an Ice Age version of a phone doodle? ("To do: Slaughter mammoth; smelt copper; cross Bering Strait.")

Still, our ancient ancestors were positively fastidious compared with their modern-day progeny. Each year the United States generates 180 million tons of trash (not including Geraldo, Oprah, and the Maury Povich Show), or four pounds per day for every man, woman, and child in the country. Much of this waste is incinerated or recycled, but much more of it is buried in landfills, where it resides as an enduring record of the people who produced it and the kinds of lives they were living at the time. For a culture with any sense of archeological perspective, this should be cause for at least a little embarrassment. Given the choice between the treasures of Tutankhamen and a few million empty Mrs. Butterworth's bottles, I know which legacy I'd prefer to leave behind. Archeologists, however, do not see things that way. More and more, these students of antiquity have been sinking their shovels into the nation's landfills, hoping to learn more about what people keep, what they throw away, and what this tells us about their culture.

Just as intriguing as landfills, which represent the end of the waste stream, are the receptacles at the beginning: trash cans. While a landfill can tell you a lot about an overall community, a study of the cans and Dumpsters near private homes can tell you even more about the individuals who make up the general population. How much paper does an average family of four discard in a year? How much food does an average household waste? Is it possible for an unmarried man to survive for an entire month on Beefaroni and Yoo-Hoo alone? Trash cans, scientists are concluding, may have the answers.

Now Timothy Jones, an archeologist and utterly-in-earnest garbologist at the University of Arizona in Tucson, has decided to take trash-picking a step further. Immersing himself in the local rubbish receptacles, he is studying a question no garbage scientist has ever looked into before: how the local citizenry cares for its teeth. For every Arizonan who claims to brush after meals, there should be an empty tube of Colgate that gets regularly discarded; for every local adult who promises to floss before bed, there should be yards of minty strands that get chucked every week; for every teen who swears to swear off sugar, there should be piles of candy wrappers that either do or don't appear in the trash. By picking through garbage cans and correlating what he finds with local dental records, Jones figures he can come up with answers to such elusive questions as which dental hygiene practices seem to work, which don't, and exactly how many metric tons of Goobers a single community can consume in a year.

"What people tell you about how they take care of themselves is not always what they really do," Jones says. "I'm trying to use the science of garbology to clear up the discrepancy."

Though few Americans have heard of garbology, the specialty is not all that new. It was in 1973 that archeologist William Rathje launched the straightforwardly named Garbage Project at the University of Arizona, with the express purpose of wedding the noble study of human society with the less noble business of trash collecting. In that year he conducted his first survey, of the trash cans outside 62 Arizona homes, to compare the amount of food purchased by families each week with the amount of food wasted. When Rathje presented himself at the subject homes and asked for permission to study the trash, he was greeted with just a little less enthusiasm than Ed McMahon and the Publishers Clearing House prize committee. Nevertheless, most of the families opened their trash cans--if not their screen doors--to the researcher, and the Garbage Project was born.

Over the next few years, Rathje conducted numerous studies on household food and paper waste before eventually moving on to landfills, where he and his detritus disciples continued to expand their data base, if not their social lives. It was only recently that Jones, a relatively new arrival at the Garbage Project, turned his attention back to the more modest garbage can work in order to study the state of Tucson's teeth.

Jones came by his interest in garbage and dentition in 1992, when a colleague approached him with a curious finding. Cornelius Steelink, a professor emeritus of chemistry serving on a health advisory board for the city of Tucson, had begun a study of the effectiveness of fluoride in preventing cavities. Fluoride, as Joseph McCarthy, Roy Cohn, and other veterans of the cold war once explained, is a substance invented by Joseph Stalin and Alger Hiss that, when added to a local water supply, can lead to stronger tooth enamel, greater decay resistance, and an overwhelming desire to annex Hungary. Later research called the last of these three phenomena into question, but the first two were proved in experiment after experiment.

Fluoride strengthens teeth by bonding with calcium, the main ingredient in enamel, to form a substance known--in the madcap argot of the chemist--as calcium fluoride. (The only substance known to bond to teeth more tightly than fluoride is spinach, particularly on first dates, when it gives the average dinner companion all the sex appeal of a smiling salad bar.) Calcium fluoride is a harder, denser material than calcium alone, making teeth more resistant to the bacteria that cause decay.

When Steelink began his study, however, the initial results puzzled him. He compared the dental records kept at schools attended by students who drank fluoridated water with those of untreated children and was surprised to find more tooth decay where there was more fluoridation. "Cornelius came to me with this really funny data," Jones recalls, "and wanted to know if there were any other variables like diet, toothbrushing, or flossing that might be playing a role. We both figured there was only one way to find out: hit the trash cans."

To see if some hidden trend in eating habits or dental hygiene was actually at work behind Steelink's data, Jones picked a number of Tucson neighborhoods for rubbish inspection. Driving around in his own car and picking up the trash himself would have been difficult and time- consuming, not to mention murder on the upholstery. Fortunately, Jones could call upon the local sanitation department to lend a hand. "All we had to do," Jones explains, "was tell the sanitation folks that we needed trash from, say, four households in census tract 14, and ask them if they wouldn't mind dropping it off when they were done with their run."

Ordering sweaters from the J. Crew catalog might have been a bit more glamorous, but it couldn't have been any easier. Most sanitation departments are more used to picking up trash than delivering it, but the one in Tucson has become accustomed to the Garbage Project's ways, and they dropped off whatever Jones requested. Unlike the University of Arizona's philosophy or economics department, whose study materials don't generally have to be stored in a Hefty Lawn and Leaf Bag, the garbology department does not conduct its work in a traditional classroom. Instead the trash-can archeologists are assigned to an outdoor sorting station consisting essentially of a large roofed area and an industrial-size freezer. When the sanitation department delivers the requested rubbish, it is put on ice, and then undergraduate volunteers help in the sorting.

"You wouldn't think there would be a lot of students interested in doing work of this kind," Jones says, "but we have plenty of them in the anthropology and archeology departments who are delighted to help out. Just to be safe, however, we do tell them that before they sign up officially, they should come by and put in a couple of days of sorting to see if they like it. Surprisingly, only about 5 percent drop out."

Whether the other 95 percent pass out, Jones doesn't say, but from the sound of the work they do, they'd certainly be entitled. After donning rubber gloves and heavy aprons (and, presumably, getting their affairs at home in order), garbage teachers and students remove the bags from the freezers and empty them onto large tables in the sorting area. As anyone knows who's ever stored a pound of coleslaw in the vegetable crisper for the Memorial Day picnic and removed it after Labor Day, cold rubbish can smell bad, but when it starts to warm up it turns truly evil. For this reason, the volunteers try to do their work fast.

The first step for the sorters in Jones's tooth study was to pick the larger items out of the bags and catalog them according to a checklist of 190 code-numbered items. "If we find a milk carton, for example," Jones explains, "we enter that as code 011. After that we enter the price, the brand, the size of the container, and the material the container is made of. Then we look inside the carton to see if there's any waste. If there is, we weigh it and enter that too. After that we work our way down to smaller and smaller stuff."

Jones and his trash trainees cataloged everything they found in every garbage bag, but what they were principally after were dental products, sugar products, and calcium-rich milk products. "The hardest thing was looking for floss," Jones says. "Little items like that tend to migrate down to the bottom of the bags, where you find cigarette butts, chewing gum, and a sort of general glop. You have to be a really dedicated sorter to get through it all."

As Jones began looking over the demographics of the neighborhoods where he collected trash, his eye was caught by three neighborhoods that had particularly high rates of tooth decay. Interestingly, they had two other things in common as well: they had fluoridated water and their populations were predominantly Hispanic. (Tucson, like most southwestern cities, is made up of three principal demographic groups: a) Hispanics, b) non-Hispanics, and c) guys who own pickup trucks with silhouettes of naked women on the mud flaps. Since most researchers define this last group less by ethnicity than by genus, however, they have focused on only the first two.) Jones went through the rest of his data and discovered that those three neighborhoods weren't statistical flukes. Neighborhoods that were supplied with fluoridated water did tend to have high tooth decay rates, as Steelink had found, but they also tended to be Hispanic.

Perhaps, Jones wondered, Hispanics might not be eating or taking care of their teeth as well as non-Hispanics. Yet the garbage refuted that idea: Hispanics and non-Hispanics consume about the same amount of toothpaste per day (.1 ounce per person), while few of either group bother to floss regularly (8.7 people per 10,000 among Hispanics versus 187 per 10,000 non-Hispanics). Hispanics consume about half as much candy per day as non-Hispanics (.33 ounce versus .64 ounce), but slightly more than twice as much bulk sugar (.88 ounce versus .38 ounce). Both groups consume about the same amount of ice cream, soda, and pastry, though Hispanics drink slightly more milk (9.24 ounces daily versus 9.01). Though neither the Hispanic nor non-Hispanic communities appeared to be living a strict Like Water for Sugar-Free Chocolate life-style, both did appear to be paying at least reasonable attention to their teeth.

Jones then considered whether Tucson's Hispanic population's past might be playing a role in its present dental health. "Since dental hygiene and current diet weren't responsible for the disparity, we could only look to past diet. If this was a community that recently emigrated from Mexico, we might conclude that prenatal or childhood nutrition was at work." That was a dead end, too. The Hispanic population under study has been in Tucson for 200 years, meaning that this was not a case of Mexican families coming across the border armed with bad eating habits. ("Give me your tired, your poor, your . . . excuse me, did you bring enough gum for all the huddled masses?")

Having eliminated these explanations, Jones is leaning more and more these days toward the hypothesis that genetics is what's at work here, causing these Hispanic residents of Tucson to react in unpredictable ways to the calcium or fluoride they consume. It's been known to happen elsewhere, says Jones. "The ideal fluoride level [for most populations] in the United States is .8 part per million, but in Japan, beyond .4 part per million, people's teeth actually become more prone to decay. The likely culprit is probably a congenital sensitivity that causes some populations to benefit from fluoridation only if the chemical is used very sparingly."

But before anyone goes hunting for a healthy-teeth-and-rosy-gums gene, Jones would still like to rule out a few remaining dietary variables. He hopes to expand his work to study broccoli and cauliflower consumption in Tucson homes; both vegetables are high in calcium and thus thought to be natural tooth builders. In addition to panning for crudités, he will also search through Tucson trash cans for evidence of Arizonans' carbohydrate consumption. While excavating week-old manicotti is the Garbage Project equivalent of handling nuclear waste, Jones believes it's worth the risk. Researchers think carbohydrates weaken teeth, perhaps because of their high levels of natural sugars, which, like processed sugars, can promote decay. Jones would also like to expand his trash picking beyond Tucson to determine whether the higher level of Hispanic cavities he discovered in the Garbage Project's hometown is strictly a local phenomenon or appears in other communities as well.

For the time being, Jones is waiting to hear whether he will secure the funding for this extended work, but while the future of his research is open to question, the future of the Garbage Project itself appears set. Unless you're thinking of becoming a proctologist, gastroenterologist, or character witness for Alfonse D'Amato, there is perhaps no less appetizing job than ash-can archeologist. Yet America continues to generate trash, and aspiring scientists continue to flock to Tucson to examine it. Long after Geraldo is canceled, there should be more than enough rubbish to keep them busy.
Comment on this article

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Collapse bottom bar

Log in to your account

Email address:
Remember me
Forgot your password?
No problem. Click here to have it emailed to you.

Not registered yet?

Register now for FREE. It takes only a few seconds to complete. Register now »