Living Downstream: A Scientist's Personal Investigation of Cancer and the Environment

Rachel Carson references World War II in Silent Spring mainly to remind readers of the introduction of wartime materials that contained new chemicals. War technology changed chemistry, and once chemicals were introduced to the civilian public, the approach to growing food, manufacturing homes, and disinfecting bathrooms also changed. Many of these chemicals weren’t tested for safety, and the war mindset of conquest and annihilation was brought into the home. Individuals born after the war are less informed about its impact on domestic life. Above her desk, Steingraber keeps a graph of synthetic materials produced since 1940. A second graph shows synthetic organic materials combined. Production of synthetic organic materials increased 100-fold in two human generations. Plastics are the synthetic materials that have grown the most.

The terms organic and synthetic are difficult to define. Organic suggests simple and close to nature—or, in science, any chemical containing carbon. Synthetic refers to material that is manufactured and doesn’t exist in nature. Most synthetic materials could be labeled organic since they have carbon atoms (plastic, nylon, DDT, and PCBs). These items derive from coal or petroleum, chemicals that contribute to the difficulty in defining organic and synthetic. Synthetic materials are based on the decomposition of plants (coal) or of animals (petroleum). Because these substances come from living entities, they’re organic. The human body contains systems to break down synthetic organic materials, so they easily interact with naturally occurring biochemicals in our bodies. However, this process allows pesticides and weed killers to interfere with and attack certain biological processes within our bodies. Inert synthetic organic materials aren’t biodegradable because their molecules are too large to decompose: “They are similar enough to naturally occurring chemicals to react with us but different enough not to go away easily” (94). Many fat-soluble synthetic organics accumulate in fatty tissue, including the breasts, liver, bone marrow, and brain.

DDT was first used in World War II to ward off the typhus epidemic in Naples and was also used to combat ticks, mosquitoes, and fleas. The surplus of DDT produced for war was turned over for general civilian use. Synthetic chemicals called organophosphates, introduced in the 1940s as an insecticide, attacked the nervous system and were tested as nerve gas on prisoners at Auschwitz during the war. The Allies introduced herbicides to destroy the enemy’s crops, and these chemicals, used as Agent Orange during the Vietnam War, were later used for weed and shrub control. While many of these chemicals are used in agriculture, private use on gardens and lawns allows them to find their way into food, water, and the air. Many studies have found correlations between home pesticide use and childhood cancers.

After the war, the US protected chemical products via high tariffs, making the chemical industry wealthy. Innovations in the use of kerosene, gasoline, artificial fertilizers, and explosives following World War I resulted in an economic boom during World War II to fill the demand for aircraft fuel, explosives, solvents, and metals. These products eventually became common in civilian life because of the threat of an economic downturn after the war. The war saw a transformation in demand from plant-based materials to those derived from oil. Many products are now made with formaldehyde, a substance linked to leukemia and several other cancers, whereas before the war, many products were made from soybean oil.

In 1976, the Toxic Substances Control Act (TSCA) revealed that many chemicals were either not tested or exempt from testing. The act doesn’t require testing and asks the EPA to balance economic benefits with safety. The TSCA requires toxicity data only when evidence of risk is demonstratable. The Federal Food, Drug, and Cosmetic Act (FFDCA) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) set legal limits for pesticide residues in food and animal feed. FIFRA requires companies that manufacture pesticides to test their products for toxicity and submit the results to the federal government. The Emergency Planning and Community Right-to-Know Act (EPCRA) and the Toxics Release Inventory (TRI) both rely on self-reporting and don’t report carcinogens in commercial products—and small businesses are exempt. Patterns show that the petroleum industry is responsible for a quarter of toxic releases, and toxic chemicals are sent to recycling facilities rather than landfills because of increased disposal costs.

The current environmental regulatory system isn’t beneficial and is “crippled by uncertainty” (116). Meanwhile, Europe is working to register all chemicals. Swift identification of cancer-causing substances should lead to decreased amounts of exposure to these chemicals. Canada’s provincial bans on cosmetic pesticides, the new European chemicals policy, and the global Stockholm Convention deserve the praise and support of cancer advocates. Green chemical design looks to nature for synthetic chemical creation, although without ways of foolproof testing, it’s difficult to know whether green chemistry is any safer. It’s also easier and cheaper to use the environment as a dumping ground for toxic waste.

Steingraber and a group of scientists examine three petri dish experiments with estrogen-sensitive breast-cancer cells. The experiment shows that endosulfan, an imported chemical found in pesticides, is estrogenic. Like the hormone it mimics, endosulfan—a testosterone-blocking chemical used in pesticides that finds its way into food sources—stimulates breast cancer cells to divide and multiply. The study also shows that multiple chemicals, even if individually weak, have a significant impact on human health when combined. Many European nations have banned endosulfan.

MCF-7, a line of cancer cells used by the Michigan Cancer Foundation, is the cell line available for study around the world. The cells were taken from a nun, Sister Catherine Frances, who died of cancer in 1970. Testing chemical and biological substances is expensive and complex, and whether petri dish experiments can closely mimic tests on lab animals is unknown. So far, the links are high. However, producing a significant and accurate test takes roughly 800 animals—usually rats and mice. Typically, scientists engage in two-year experiments to examine developing tumors. Just testing one chemical takes significant time, and about 80,000 chemicals are on the market, with hundreds added each year, so resources are insufficient to test all chemicals. The International Agency for Research on Cancer has conducted 900 tests since 1971, and 400 of them noted the existence of or potential for human carcinogens. In the US, the National Toxicology Program has conducted roughly 600 tests, and half showed carcinogens. Only chemicals identified as problematic are tested. Toxicologists estimate that less than 5% to 10% of all chemicals in commercial use might reasonably be considered human carcinogens.

In 2007, the National Research Council began using automated (robot) tests. These rapidly performing tests can evaluate thousands of chemicals at a time. However, interpretation of data on tens of thousands of chemicals isn’t possible. Although animals are no longer efficient in chemical testing, dog testing revealed significant information about the synthetic use of dyes in the textile industry. Additionally, when these dyes were added to rubber and antirusting agents, workers in the tire and machine industry became ill with bladder cancer. Exposure to flea and tick chemicals had similar results. Military dogs in Vietnam exposed to Agent Orange developed testicular cancer. Lab animals will continue to be used until petri dish experiments are developed.

Breast cells during early development are particularly susceptible to chemical carcinogens. Studies on rats demonstrate that an abundance of cells in the terminal end buds of a developing breast or a delay in bud maturation can increase the risk of breast cancer. Rats exposed to atrazine had different interior anatomy than rats that weren’t exposed. Nursing rats gained less weight, and mothers had undeveloped mammary glands. These results wouldn’t be possible with cell line experiments. However, the development of cancer in these rats does not happen the same way as in humans.

Bladder cancer in beluga whales in the North Atlantic share characteristics of an increase in bladder cancer among workers in a nearby aluminum smelter along the St. Lawrence River. Benzo[a]pyrene, a chemical resulting from the combustion of wood, gasoline, and tobacco, was found in tumors of four dead belugas that washed ashore, and one young whale exhibited abnormal breast development. St. Lawrence River belugas are dying at a much faster rate than those in the Arctic. Dissolved pollutants in the whale fat may be causing reproductive issues. Other nonlocal pesticide contaminants may appear because of drifting wind or in eels that migrate from Lake Ontario. Mirex, a foreign chemical, was once reportedly spilled into the water from a pesticide manufacturing plant.

In 1964, pathologist and physician Clyde Dawe discovered white suckers with liver cancer in a lake in Maryland. Dawe’s was the first discovery of wild fish with liver cancer. Further studies at Dawe’s request revealed that liver cancer in fish is linked to the environment. Many of these fish are bottom feeders and exist in polluted waterways. Additionally, aquarium studies in the laboratory show that the carcinogens known to cause cancer in humans and rodents also cause cancer in fish and mollusks—and are often metabolized in the same way.

Steingraber concludes the chapter with an idea for a pilgrimage. People with cancer should travel to various bodies of water known to be inhabited by animals with cancer. The pilgrimage would convene at Buffalo Rock, a place known to have been ravaged by a strip mine in the 1930s that polluted the soil with highly toxic shale and pyrite, killing all life forms there.