Using Toxins: Short Term Gains, Long Term Pain
Over half of all antibiotics produced in the U.S. are used in livestock production. Should we be concerned about antibiotics in the environment and the meat we eat?
The widespread use of antibiotics as a feed supplement, a common practice in Concentrated Animal Feeding Operations (CAFOs) represents a technology intervention of the late 20th century that showcases our unthinking ability to focus on profits while overlooking the ecosystem level consequences of our actions. The collateral effects of feeding sub-therapeutic doses of antibiotics to agricultural animals represent externalities that were neglected in our cost and benefit analyses.
In addition to the inhumane treatment suffered by the billions of animal animals we raise to slaughter, we are also producing a large reservoir of antibiotic resistance in common microbes and releasing antibiotics into the environment. In addition to antibiotic resistance, antibiotics in the meat we eat can affect microbial ecosystems within our GI tracts. The GI tracts of all animals – mammals, other vertebrates, and invertebrates – display the complex communities of microorganisms that contribute directly to their long-term health.
The adverse consequences of widespread antibiotics use, with regard to public health, are significant. Vulnerable populations are primarily those who have weak or compromised immune systems, such as cancer patients, children and seniors, people living with HIV/AIDS and diabetes, and people who have undergone organ transplants.
There is no particular group to blame for this situation. We have to accept our ignorance and reconsider our options for the future. WE can do better, if we work together.
The Web of Life
The Cambrian period, when macroscopic hard-shelled animals first appeared in abundance, started about 540 million years ago. Based on current science, unicellular microbial life existed on Earth at least 3.5 billion years ago.
Life, as we know it, is a highly integrated network of consumers and producers which have co-evolved since then. These extended relationships or supply chain networks are highly resilient with regard to most environmental perturbations and have survived the tests of time.
Symbiosis
Lynn Margulis is one of my favorite scientists who integrated biology and biochemistry. She did a brilliant job of synthesizing how the impacts of environmental and evolutionary pressures drove the original single celled, prokaryotic cellular life forms to develop into the eukaryotic archetype that forms the basis of all multi-cellular life around us.
Professor Margulis proposed that symbiosis should be recognized as a primary driving force in evolution. Her hypothesis has now been validated and symbiogenesis is recognized as the evolutionary driving force behind the creation of the eukaryotes, i.e., cells with a membrane around their nucleus, from the prokaryotes. All the macroscopic plants and animals that we see around us are eukaryotes.
With this understanding of Life, and of its resilience – i.e., its ability to transform and survive the numerous chemical and physical assaults over geological time, we should have been more careful about how we tried to control the creatures around us. The ones we regarded as undesirables or pests.
Perhaps our rash and misguided actions occurred because disciplines like Biology and Ecology were still considered to be “soft science” just fifty years ago and because they had not collected the data needed to get our attention.
The development of computers and the application of advanced numerical methods allowed us to develop powerful analytical instrumentation to track toxins in the environment and provided scientists with the ability to archive and evaluate large amounts of data in the biological realm. It changed our understanding of the world at large and about how toxins migrate though the biosphere.
The Toxic Hammer
Human beings are a part of the connectedness of life on this planet, the web of life, also known as Gaia. We may have chosen to study the relationships between the plants and animals we wished to control and used the resources provided by Nature. Instead, we chose the newly found genius of post World War II industrial chemistry to discover technical solutions and to generate commerce. A commerce based on ingenious means to implement death.
We synthesized millions of tons of diverse chemical agents (toxins) to block selected enzymatic processes in the targeted animals (e.g., pests) and plants (e.g., weeds) that we wished to eliminate. We also developed the means to deliver them very successfully, around the world.
Rachel Carson was an early visionary who spoke about the unexpected impacts of these toxins on the life around us. We were somewhat hard of hearing then. Perhaps we were not ready to assimilate what the biologists and the ecologists said, about the widespread devastation they were seeing.
Lessons Learned
And now, we find these same toxins within our bodies. The Web of Life has returned to us what we have sown, what we cast on the waters. We are just beginning to understand how our rash and misguided actions have come back to haunt us.
There is increasing awareness and concern that the synthetic molecules we create are not breaking down. They persist and are accumulating in the environment and in organisms (i.e., bioaccumulation). And they are finding their way up the food chains.
Though often present in the environment at low levels (i.e., < 1 part per million) these persistent chemicals partition into the bodies of the plankton and macroinvertebrates, with their relatively large surface area to volume ratios, and then into the bodies of the fish and the amphibians that eat them. And then up the food chain into the bodies of amphibians and reptiles and the birds that eat the insects, and finally, into the mammals.
At each stage in the food chain, concentrations of persistent toxic compounds increase geometrically, due to a phenomenon known as biomagnification. Depending on the compounds and food webs involved, biomagnification factors of a million are possible.
There are two ways in which these toxins affect us and other organisms. At high levels, as seen with acute exposures, they can cause mortality (e.g., mass animal, bird, and fish and insect deaths) or significant morbidities, such as failure to thrive or poor reproductive outcomes. At lower levels, and with chronic, long-term exposure, we see persistent inflammatory responses.
Hormesis & Immune Systems
Hormesis is the activation of the immune system to due low level exposures to toxins and other agents (e.g., ionizing radiation) that represent threats at the cellular level. These immune system responses can “stack” or combine to result in a broad range of clinical signs and diverse symptoms.
Some examples include allergies and food sensitivities, arthritic syndromes and degenerative changes in the musculoskeletal system, cardiovascular and neurological diseases, and endocrine system disorders such as diabetes, hypothyroidism, polycystic ovarian syndrome. With our current understandings of developmental programming, we also recognize that parental exposures to toxins may be transmitted to offspring by epigenetic mechanisms.
The impact of multiple low level exposures to toxic synthetic compounds is an active area of current research. These studies will undoubtedly enlighten us about how the consequences of our past actions will affect public health, around the planet, in the decades to come.
With adequate funding and public support, we hope to identify cost-effective approaches to mitigate these some of these impacts. It is very likely source reduction measures and the prevention of exposure to toxins will emerge as the winner.
Looking Ahead…
Perhaps these actions of the 20th century will teach us that the Earth, though silent for a time, integrates all perturbations. We are learning of a planetary scale “memory”, if you will, that is integral to Gaia.
The hard lessons will continue till we learn that we live together, as partners and stewards, and develop a more integrated vision of the Web of Life.
As the Native Americans say, Mitakuye Oyasin …