Testing tar-based water bottles for the transmission of dangerous toxins
Keeping potable water portable has been one of humanity’s big challenges. The different flavors and smells of water are thanks to all the different materials water can pick up and carry from its containers, from stream beds to lead pipes. Some containers are more concerning than others, including some of our favorite plastics of today. As those bottles break down, small amounts of molecules like BPAs can end up in your water. As much as people are trying to avoid these contaminants today, they’re rather benign compared to the first “plastic” water bottles, which were made of something regarded as “nature’s asphalt.”
Bottled in bitumen
Bitumen is a form of petroleum that can be functionally solid at room temperature, but usually oozes like a very viscous liquid over long amounts of time. It’s composed of a variety of compounds, and can be found in a variety of natural settings, such as sandstone, bubbling up under lakes, or for the paleontologists, the La Brea Tar Pits in Los Angeles. Native American tribes living on islands of the coast of Southern California, collectively known as the Chumash, also found bitumen washing up on their beaches. The little balls of tar seep out of fissures under the ocean, and with a little work, the Chumash peoples realized that bitumen could also seal water into a container better than ceramics or skins.
The recipe for a Chumash water bottles required plant-fiber nets, pitch from trees, an abalone shell and of course a lot of bitumen. The netting was a framework to make the overall shape, which was generally bulbous with a narrow spout on the top. The shell helped provide some initial structure at the bottom, and the rest was made by slathering melted bitumen and pitch along the netting. It’s a sticky, smokey process, but researchers recently recreated it so that they could test exactly how many toxins these bitumen bottles may have been.
Safe to sip and sup?
The carefully recreated bottles were left to hold water for two months to simulate the passage of time, then tested. Mass spectrometry found that the water had picked up naphthalene, phenanthrene, and acenaphthalene, all of which can be toxic if ingested. Tests were also conducted with olive oil instead of water in order to simulate contact with other foods, since there is evidence that Chumash people ate meats and fish off bitumen-based bowls or plates. The olive oil picked up more toxins, but it may not be a perfect proxy for what the Chumash were actually eating. In the end, the most dangerous component in all these products was the smoke made during their production. That wouldn’t have harmed as many people, but anyone regularly making bitumen water bottles likely paid a price to do so.
These investigations weren’t just interested in water bottle technology. Skeletons of Chumash people from around 5,000 years ago turn up with an unusual number of health problems, including poor bone quality, smaller skulls, and bad teeth. The data from the recreated bitumen water bottles don’t fully explain these health problems, although it’s a tough connection to prove at this point. Most studies of toxicity are based around people that still have enough flesh to damage, and so there’s not a lot of information if you want to know how naphthalene might affect bones over a lifetime. Still, the amount of toxins leached into the water, oil and of course, smoke, do suggest that these water bottles contributed to health problems at a minimum.
Source: Plastic Water Bottles Might Have Poisoned Ancient Californians by Nick Stockton, Wired