Chemical pollution and the release of novel entities (Stockholm Planetary Boundaries)
“Emissions of toxic and long-lived substances such as synthetic organic pollutants, heavy metal compounds and radioactive materials (emphasis added) represent some of the key human-driven changes to the planetary environment. These compounds can have potentially irreversible effects on living organisms and on the physical environment (by affecting atmospheric processes and climate). Even when the uptake and bioaccumulation of chemical pollution is at sub-lethal levels for organisms, the effects of reduced fertility and the potential of permanent genetic damage can have severe effects on ecosystems far removed from the source of the pollution. For example, persistent organic compounds have caused dramatic reductions in bird populations and impaired reproduction and development in marine mammals. There are many examples of additive and synergic effects from these compounds, but these are still poorly understood scientifically.
At present, we are unable to quantify a single chemical pollution boundary, although the risk of crossing Earth system thresholds is considered sufficiently well-defined for it to be included in the list as a priority for precautionary action and for further research.”
Biocide Planetary Boundary
In a recent paper (Nature Sustainability 1, 632-641 (2018) “Antibiotic and pesticide susceptibility and the Anthropocene operating space. 10.1038/s41893-018-0164-3)
“The team defined and assessed the state of the planetary boundary for six types of resistance including: antibiotic resistance in Gram-negative and Gram-positive bacteria; general resistance to insecticides and herbicides and resistance to transgenic Bt-crops and glyphosate resistance in herbicide resistant cropping systems. All six assessed boundaries are in zones of increasing risk and three out of six are in zones of high regional or global risk.”
State of the Anthropocene operating space of biocide susceptibility
- Antibiotic susceptibility is globally surpassed for Gram-negative bacteria and in the uncertain zone for Gram-positive bacteria.
- Pesticide susceptibility is generally assessed as being in the uncertain zone, but surpassed at the regional level in genetically engineered cropping systems owing to increasing resistance to foundational pesticides.
- Insecticide resistance is assessed as being in the uncertain zone, given that multiple insecticide resistance is increasing in several pests.
- In plants, multiple herbicide resistance is increasing and leads to an assessment of general herbicide use as being in the uncertain zone.
- For Bt crops, the spread of resistance to regionally available Bt-crop toxins in the US mid-west and in India leads to an assessment of regionally surpassed.
- For herbicide resistant crops, the increasing spread of glyphosate resistance leads to its assessment as regionally surpassed
Global Assessment: for all major types of antibiotics and pesticides considered, we are today in a situation where resistance puts current practices at increasing risk
Persistant Organic Pollutants (POPs)
Source: Stockholm Convention
Persistent Organic Pollutants (POPs) are organic chemical substances, that is, they are carbon-based. They possess a particular combination of physical and chemical properties such that, once released into the environment, they:
- remain intact for exceptionally long periods of time (many years);
- become widely distributed throughout the environment as a result of natural processes involving soil, water and, most notably, air;
- accumulate in the fatty tissue of living organisms including humans, and are found at higher concentrations at higher levels in the food chain; and
- are toxic to both humans and wildlife.
As a result of releases to the environment over the past several decades due especially to human activities, POPs are now widely distributed over large regions (including those where POPs have never been used) and, in some cases, they are found around the globe. This extensive contamination of environmental media and living organisms includes many foodstuffs and has resulted in the sustained exposure of many species, including humans, for periods of time that span generations, resulting in both acute and chronic toxic effects.
In addition, POPs concentrate in living organisms through another process called bioaccumulation. Though not soluble in water, POPs are readily absorbed in fatty tissue, where concentrations can become magnified by up to 70,000 times the background levels. Fish, predatory birds, mammals, and humans are high up the food chain and so absorb the greatest concentrations*. When they travel, the POPs travel with them. As a result of these two processes, POPs can be found in people and animals living in regions such as the Arctic, thousands of kilometers from any major POPs source.
Specific effects of POPs can include cancer, allergies and hypersensitivity, damage to the central and peripheral nervous systems, reproductive disorders, and disruption of the immune system. Some POPs are also considered to be endocrine disrupters, which, by altering the hormonal system, can damage the reproductive and immune systems of exposed individuals as well as their offspring2; they can also have developmental and carcinogenic effects.
1. POPs and bioaccumulation impacts in apex marine predators: Jepson, Paul D., and Law, Robin J. 2016. Persistant pollutants, persistent threats, Science 352,6292, pp. 1388-1389. DOI: 10.1126/science.aaf9075
2. For example, see a discussion of Michael Skinner’s work on transgenerational effects of exposure to epigenetic effects of exposure to DDT, permethrin, jet fuel, phthalates, bishphenol A, and dioxin: Kaiser, Jocelyn, 2014. The Epigenetics Heretic, Science, vol 343, 6169, pp361-363 DOI: 10.1126/science.343.6169.361