Ecotoxicity

Source: Wikipedia, the free encyclopedia.
Pesticide distribution
Oil spill
ecosystems
. Such stressors could occur in the natural environment at densities, concentrations, or levels high enough to disrupt natural biochemical and physiological behavior and interactions. This ultimately affects all living organisms that comprise an ecosystem.

Ecotoxicology has been defined as a branch of toxicology that focuses on the study of toxic effects, caused by natural or synthetic pollutants. These pollutants affect animals (including humans), vegetation, and microbes, in an intrinsic way.[1]

Acute vs. chronic ecotoxicity

According to Barrie Peake in their paper “Impact of Pharmaceuticals on the Environment.”, The ecotoxicity of chemicals can be described based on the amount of exposure to any hazardous materials. There are two categories of ecotoxicity founded off of this description: acute toxins and chronic toxins (Peake, 2016). Acute ecotoxicity refers to the detrimental effects resulting from a hazardous exposure for no more than 15 days. Acute ecotoxicity is the direct result from the interaction of a chemical hazard with cell membranes of an organism (Peake, 2016). This interaction often leads to cell or tissue damage or death. Chronic ecotoxicity on the other hand are the detrimental effects resulting from a hazardous exposure of 15 days, to possibly years (Peake, 2016). Chronic ecotoxicity is often associated with “particular drug–receptor actions that initiate a particular pharmacological response in an aquatic or terrestrial organism.” (Peake, 2016). Due to this interaction, chronic ecotoxicity is usually not lethal in the way that acute ecotoxicity is. However, chronic ecotoxicity decreases cellular biochemical functions. This often results in alterations to psychological or behavioral responses of the organism to environmental stimuli (Peake, 2016).

Common environmental toxicants

  1. Diethyl phthalate- enters the environment through industries manufacturing cosmetics, plastic, and other commercial products.
  2. Bisphenol A (BPA)- found in mass-produced products such as medical devices, food packaging, cosmetics, children's toys, computers, CD's, etc.
  3. Pharmaceuticals- a fungicide found in anti-dandruff shampoos. The most common example of this is Climbazole.
  4. Pesticides
  5. Some but not all:
    oven cleaners, and disinfectants
    .
  6. Phosphates
  7. Oil

Household products

In Canada, there is no law requiring manufacturers to state the health and

absorption through the skin. When these cleaning products are washed down the drain, they can negatively affect aquatic ecosystems
. There are also no regulations in place stating that the ingredients must be listed on labels of cleaning products. This often leads users to be unaware of the chemicals they expose themselves and their surrounding environments to.

Fragrance chemicals

Fragrance chemicals are found in most cleaning products, perfumes, and personal care products. More than 3000 chemicals are used in these fragrance mixtures. The synthetic musks used in detergents accumulate in the environment and are harmful to aquatic organisms. Certain musks are possible endocrine disruptors
that interfere with hormone functioning. Phthalates are a common ingredient in these fragrance mixtures found in laundry detergents and fabric softeners. These phthalates (suspected endocrine disrupters) affect reproduction rates, including reduced sperm count in males. Certain glass cleaners and floor polishes contain dibutyl phthalate (DBP). The European Union classifies DBP as very toxic to aquatic organisms. This poses a huge danger as these cleaners, especially the floor polishes, are often rinsed down the drain and into aquatic environments.

Phosphates

hypoxic zones
.

Quaternary ammonium compounds (quats)

antibiotic resistant
bacteria, thus limiting microbial infection treatment options.

Trisodium nitrilotriacetate

Trisodium

heavy metals in sediment to redissolve into water. Many of these metals are toxic to fish and other wildlife.[2]

Antimicrobial chemicals

Main article: Antimicrobial

Personal care products can reach the environment through drainage from waste water treatment plants and digested sludge. Recently, the

oats and turnip included stunted growth of the leaves and shoot, as well as turning darker in color. The aquatic ecotoxicity of climbazole can be classified as very toxic to Lemna and algae, toxic to fish, and harmful to Daphnia.[3]

Plasticizers

Cyprinus carpio, liver size was observed to increase and testis size decreased. In fish muscle, ALT and AST activities decreased due to DEP treatment. Like many toxic chemicals, DEP has been known to affect metabolic enzyme profiles and phosphates and transaminases activities, Ghorpade et al. as cited by.[5] A decrease in immunity of M. rosenbergii
after exposure to DEP was also noted. Given that certain biological effects occur due to chemical concentrations found in plasticizers used in the laboratory coincide with concentrations present in the environment, certain wildlife species must be negatively impacted.

Pesticides

Pesticides often pose serious problems to the environment. They kill not only targeted organisms, but also non-targeted organisms in the process. Pesticides are released into the natural environment intentionally by people who are often unaware that these chemicals will travel further than anticipated, Hatakeyama et al. as cited in.[6] Thus, pesticides largely affect the natural communities in which they are used. They negatively affect multiple levels, ranging from molecules, to tissues, to organs; to individuals, to populations, and onto communities. In the natural environment, a combination of pesticide exposure and natural stressors such as fluctuating temperature, food shortages, or decreased oxygen availability are worse than when presented alone. Pesticides can affect the feeding rates of zoo-plankton. In the presence of pesticides, zoo-plankton display lower feeding rates which result in reduced growth and reproduction. Swimming may also be affected by pesticides, which poses a life-threatening issue for zoo-plankton as they swim to obtain food and avoid predators. Such changes may alter predator-prey relationships. A spinning behavior became apparent in Daphnia when induced by carbaryl. The presence of carbaryl increased the probability of the Daphnia being eaten by other fish, Dodson et al. as cited by.[6] The toxicant pentachlorophenol increases swimming speed in the rotifer Brachionus calyciflorus. This in turn increased the encounter rate of predators, Preston et al. as cited by.[6]

Oil spills

One of the major environmental impacts of oil exploration on the environment is the contamination of aquatic ecosystems from

phototoxic. This area, which has poorly developed infrastructure, is one where residents collect water for drinking, cooking, and bathing from the rivers and ponds nearby. "A recent study observed excess cancer rates in a village in this region" Sebastian et al., as cited in.[7] Not only were excess cancer rates apparent, but many people in this area that were consuming the water became ill. In Wernersson's study, toxicity of water and sediment samples were studied on Daphnia magna (a crustacean zoo-plankton species) and Hyalella azteca (an amphipod). These samples were collected from four sites where crude oil was the main source of pollution. 1-4 day-old organisms of both species were used in the tests. Immobility of D. magna was recorded after 24 hours of exposure indoors. They were then moved outdoors where they were exposed to sunlight. After 1-2 hours, the samples were removed from the sunlight. It was found that D. magna often recovered within an hour after UV exposure. Hyalella azteca was cultured in the same medium as was used for the D. magna species. To minimize stress, shade was provided. 16 hours of light and 8 hours of darkness were provided. Lethality
was recorded after 96 hours of exposure.

Overall environmental impact

Ecotoxicity has given us a better understanding of the extent of damage caused by the release of toxic chemicals into our environment. According to the National Library of Medicine; “Current estimates project that every year, a combined load of millions of tons of potentially toxic chemicals enters the environment from a broad range of industrial and domestic processes.” (Fantke, 2020). Some of these toxic chemicals are discharged into lakes, rivers, the ocean, and groundwater. Animals, plants, and water surfaces can also be exposed from airborne chemical emissions caused from cities, factories, and fires (Fantke, 2020). Chemical sludge often gets into agricultural and industrial soils as well.

These chemicals degrade into the environment and can become toxic metabolites. When this happens they “have the potential to bioaccumulate and biomagnify in species of higher trophic levels.” (Fantke, 2020). This can result in a wide variety of consequences, including but not limited to: the extinction of environmentally sensitive species, alterations to local food webs, physiological and genetic changes, and changes in reproduction, growth, and behavior (Fantke, 2020). Although much research into ecotoxicity has been done, there is still uncertainty about the true extent of damage caused. There may be long-term consequences on the structure and function of local and global ecosystems we are yet to understand.

See also

References

  1. PMID 617089
    .
  2. ^ a b Suzuki, David. "The dirt on toxic chemicals in household cleaning products". David Suzuki Foundation, Solutions are in our nature. The David Suzuki Foundation. Archived from the original on 3 April 2016. Retrieved 3 April 2016.
  3. S2CID 26085318
    .
  4. ^
    PMID 19528055
    .
  5. ^
    doi:10.1016/j.pestbp.2006.08.009
    .
  6. ^
    PMID 11202648
    .
  7. ^
    S2CID 85057760
    .

Further reading

External links
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