DDT still harms birds of prey, 50 years after it was banned

DDT still harms birds of prey, 50 years after it was banned

(Beyond pesticides, May 31, 2022) Fifty years after DDT was banned, the notorious insecticide continues to harm iconic birds of prey along the California coast. According to research published in Environmental science and technology, California condors and marine mammals along the California coast are contaminated with several dozen different halogenated organic compounds (hazardous, often chlorinated chemicals) related to DDT, chlordane, and other now-banned legacy chemicals. The findings underscore the incredible importance of tackling these original “eternal chemicals” and ensuring that we don’t continue to repeat the mistakes of the past with new and different, but equally dangerous chemicals.

Between 1947 and 1971, California’s Montrose Chemical Corporation, the largest historical producer of DDT, dumped over 1,700 tons of DDT into the Los Angeles sewer system, which eventually ended up in the Pacific Ocean. . Meanwhile, several other companies released PCBs, causing further chemical contamination of land and sediment. As late as April 2021, scientists found 25,000 barrels likely containing DDT near Catalina Island, along the southern California coast.

These discharges have caused serious environmental and health problems throughout the coastal food chain. Yet, as this study shows, scientists are only beginning to understand the far-reaching effects.

DDT and similar halogenated organic compounds pose significant risks to bird populations. Throughout the 1960s, populations of birds of prey declined precipitously across the United States, similar to the severe decline in pollinators now being experienced with the continued use of neonicotinoid insecticides. DDT biomagnifies in the food chain; the chemical does not break down, and as each animal in the food chain consumes contaminated prey, the amount of chemical builds up, increasing toxicity to apex predators. Birds that consume large amounts of DDT-contaminated fish and other marine organisms are more likely to experience eggshell thinning. Thin eggs crack and become non-viable in the nest, leading to widespread inability to procreate among birds of prey in the mid-20e century.

In 1987, only 27 California condors remained. It took 40 years of captive breeding to grow the population to its current level of 537, but as this study highlights, the same threats remain. “The abundance is so high in Southern California,” said Eunha Hoh, PhD, study co-author and researcher at the San Diego State School of Public Health. Los Angeles Time. “We can’t just move on…our ocean is so much more polluted with DDT.”

Scientists are assessing the continuing threat of contamination from DDT (and DDT-related compounds) by comparing blood plasma samples from California condors and coastal marine life from different locations in California. Using two-dimensional gas chromatography coupled with time-of-flight mass spectrometry, levels of halogenated organic compounds were determined for inland and coastal Californian condors, as well as marine mammals (various species of dolphins , California seals and sea lions) from both Baja California, Mexico and Southern California.

In summary, the researchers identified 415 unique halogenated organic compounds in the samples tested. Nine classes of compounds found, likely related to past chemical spills, were unknown to scientists. Coastal condors contained four times more halogen compounds than inland condors, and marine mammals along the southern California coast contained three times higher levels than those located in Baja California. For DDT alone, condors on the California coast had blood concentrations seven times higher than their inland neighbors.

“Our ongoing work has demonstrated that the more years a female condor spends on the coast, and therefore likely feeds on marine mammals, the lower the likelihood of her egg hatching,” said toxicologist Myra Finkelstein, PhD. environmental at UC Santa Cruz. Los Angeles Time.

According to previous reports, thinning eggshells have been observed in California coastal condors since 2006. These coastal populations have been observed feeding on the carcasses of various marine species, including highly contaminated seals and sea lions. Condors along Big Sur experience hatching success as low as 20-40%, while those further inland near Tejon experience rates of 70-80%. Perhaps the silver lining of current research is the relatively lower levels of contamination found in Baja California, indicating that this location is a possible site for coastal reintroduction.

As we deal with the toxic legacy of long-banned pesticides, we must take action to stop the chemical disasters now brewing due to the use of new, long-lived chemicals. Neonicotinoid insecticides can persist in soils for years, resulting in continuous reuptake by plants, from which pollinators feed and subsequently experience lethal or sublethal exposure. PFAS chemicals, the next generation of “forever chemicals,” are ubiquitous in farmland across the United States. Species cleanup and recovery is a decades-long affair that society needs to take preventative action to prevent.

Take action today to urge lawmakers to pass real and meaningful reforms to federal pesticide law to ensure we have the tools necessary to prevent the next man-made ecological crisis. As Rachel Carson has written, “Can anyone believe that it is possible to deposit such a barrage of poisons on the surface of the Earth without rendering it unfit for all life?

All unattributed positions and opinions in this article are those of Beyond Pesticides.

Source: Los Angeles Time, Environmental science and technology