There are many sources of environmental
toxicity that can lead to the presence of toxicants in our food, water and air. These sources include organic and inorganic pollutants,
pesticides and biological agents, all of which can have harmful effects on living organisms. There can be so called
point sources of pollution, for instance the drains from a specific factory, but also
non-point sources (diffuse sources) like the rubber from car tires that contain numerous chemicals and heavy metals that are spread in the environment.
PCBs PCBs are organic pollutants that are still present in our environment today, despite being banned in many countries, including the United States and Canada. Due to the persistent nature of PCBs in
aquatic ecosystems, many aquatic species contain high levels of this chemical. For example, wild
salmon (
Salmo salar) in the
Baltic Sea have been shown to have significantly higher PCB levels than farmed salmon as the wild fish live in a heavily contaminated environment. PCBs pertains to a group of human-produced "organic chemicals known as Chlorinated hydrocarbons" The chemical and physical properties of a PCS determine the quantity and location chlorine and unlike other chemicals, they have no form of identification. For example, because humans consume fish, it is important to monitor fishes for such trace metals. Moreover, cadmium can potentially alter the productivity and mating behaviours of these fish. Heavy metals can also alter the genetic makeup in aquatic organisms. In Canada, a study examined genetic diversity in wild yellow perch along various heavy metal concentration gradients in lakes polluted by mining operations. Researchers wanted to determine what effect metal contamination had on evolutionary responses among populations of yellow perch. Along the gradient, genetic diversity over all loci was negatively correlated with liver cadmium contamination. Additionally, there was a negative correlation observed between copper contamination and genetic diversity. Some aquatic species have evolved heavy metal tolerances. In response to high heavy metal concentrations a Dipteran species,
Chironomus riparius, of the midge family, Chironomidae, has evolved to become tolerant to cadmium toxicity in aquatic environments. Altered life histories, increased cadmium excretion, and sustained growth under cadmium exposure is evidence that shows that
C. riparius exhibits genetically based heavy metal tolerance. Additionally, a case study in China looked at the concentrations of Cu (copper), Cr (chromium), Cd (cadmium), and Pb (lead) in the edible parts of the fishes
Pelteobagrus fluvidraco, the banded catfish, and
Cyprinus carpio, the common carp living in Taihu Lake. When humans and animals are exposed to high radiation levels, they can develop
cancer,
congenital disabilities, or skin burns. Plants also face problems when exposed to large levels of radiation. After the
Chernobyl disaster in 1986, the nuclear radiation damaged the surrounding
plants' reproductive tissues, and it took approximately three years for these plans to regain their reproductive abilities. The study of radiation and its effects on the environment is known as
radioecology.
Metals toxicity The most known or common types of heavy metals include zinc, arsenic, copper, lead, nickel, chromium, aluminum, and cadmium. All of these types cause certain risks on human and environment health. Though certain amount of these metals can actually have an important role in, for example, maintaining certain biochemical and physiological, "functions in living organisms when in very low concentrations, however they become noxious when they exceed certain threshold concentrations." Heavy metal are a huge part of environmental pollutions and their toxicity "is a problem of increasing significance for ecological, evolutionary, nutritional and environmental reasons." Those natural processes release more aluminum into the freshwater environments than do humans, but anthropogenic impact has been causing values to rise above the recommended amount by the U.S. EPA and World Health Organization. Humans tend to encounter arsenic by "natural means, industrial source, or from unintended sources." However, past use of leaded gasoline has contributed to lead present in soil. Some sources of lead pollution in the environment include metal plating, fishing operations, soil waste, factory chimneys, smelting of ores, wastes from battery industries, paint, agrochemicals, and legacy lead-based infrastructure such as old plumbing and paints. Lead enters the body primarily through inhalation or ingestion of contaminated air, food, water, or soil from these sources. Lead can have multiple effects on the body's systems, including the central and peripheral nervous systems. Someone who has come in contact with lead can have either acute or chronic lead poisoning. Those who experience acute poisoning have symptoms such as loss of appetite, headache, hypertension, abdominal pain, renal dysfunction, fatigue, sleeplessness, arthritis, hallucinations, and vertigo. Plankton then get the metal into their system, and they are then eaten by other marine organisms. This can happen through renal dysfunction or bone damage.
Chromium The 7th most abundant element, chromium, can occur naturally when one burns oil and coal and is released into the environment through sewage and fertilizers. Chromium usage can be seen in, "industries such as metallurgy, electroplating, production of paints and pigments, tanning,
wood preservation, chemical production and
pulp and paper production." These pesticides impair their immune, nervous, behavioral systems including causing lower fertility rates, abnormal hormone levels, and lower fitness of offspring. They are mainly used for crops such as corn, rice, soybean, sunflower, cotton, among others and are able to stay in the environment for long periods of time. Shockingly, its use was still prevalent in the U.S. in 2016 and in Australia for some time. The government . worked with conservation groups in helping them breed out of the contaminated area. Finally, in 1999 the birds were taken off the U.S endangered species list. PFAS chemicals have been linked to high cholesterol, altered kidney and thyroid function, ulcerative colitis, immunosuppression, decreased effectiveness of vaccines, low birth weight, reproductive issues, and cancers such as kidney, testicular and liver cancer. However, we are still uncovering the full health effects of these chemicals. PFAS chemicals are now ubiquitous in the environment, recent research found PFAS chemicals in all rain water studied. DuPont and 3M had both done internal studies on the potential harmful effects of these chemicals, and had known for decades of their potential to cause cancers and low birth weight. Yet this research was not made public and the companies continued to make large profits off the harmful chemicals. In 2000 3M announced they will voluntarily halt production of PFOA and PFOS — technically known as "long-chain" chemicals — and will stop putting them in products by 2002. They replaced these chemicals with new "short-chain" PFAS formulations, but scientists have found these replacements to be possibly just as hazardous. Lawsuits around the world have now sprung up against companies and governments who knew of the harm these chemicals could do and continued to use them. Regulation talks on these chemicals is now happening world-wide. Remediation of these "
forever chemicals" has been attempted in hot spots around the world, by placing the contaminated soil in landfill or heating at extremely high temperature. However, these are both very expensive, and new, cheaper remediation tools are desperately required.
Organophosphate chemicals Organophosphate pesticides (OPs) are ester derivatives of phosphorus. These substances are found in pesticides, herbicides, and insecticides and were generally thought to be safe because they degrade quickly in the natural environment assuming there is sunlight, air, and soil. More specifically, it showed higher ecological risks for Daphnia compared to other marine organisms. Cyanotoxins can be dermatotoxic, neurotoxic, and hepatotoxic, though death related to their exposure is rare. Despite their known toxicities, developing a specific biomarker of exposure has been difficult because of the complex mechanism of action these toxins possess.
Cyanotoxins in drinking water The occurrence of this toxin in drinking water depends on a couple of factors. One, is the drinking water's level in raw source water and secondly, it depends on the effectiveness of removing these toxins from water when drinking water is actually being produced. Due to being no data on the absence/presence of these toxins in drinking water, it is very hard to actually monitor the amounts that are present in finished water. This is a result of the U.S not having state or federal programs in place that actually monitor the presence of this toxins in drinking water treatment plants.
Effects on humans Though data on the effects of these two toxins are limited, from what is available it suggests the toxins attack the liver and kidney. There was an hepatoenteritis-like outbreak in Palm Island, Australia (1979), due to the consumption of water that contained, "
C. raciborskii, a cyanobacteria that can produce cylindrospermopsin." Most cases (typically involving children) have required they be taken to a hospital. The results of hospitilation include: Vomiting, kidney damage (due to lose of water, protein and electrolytes) fever, bloody diarrhea, and headaches. ==Societies==