Environmental toxicology

Environmental toxicology

Overview of the interdisciplinarity of environmental toxicology

Environmental toxicology, also known as entox, is a [1][2] Ecotoxicology is a subdiscipline of environmental toxicology concerned with studying the harmful effects of toxicants at the population and ecosystem levels.

Rachel Carson is considered the mother of environmental toxicology, as she made it a distinct field within toxicology in 1962 with the publication of her book Silent Spring, which covered the effects of uncontrolled pesticide use.

Organisms can be introduced to toxicants at various stages of their life cycle. The degree of toxicity can vary depending on where the organism is found within its trophic cascade and the biomagnification of specific toxicants. Biodegradation releases CO2 and water as by-products into the environment. This process is typically limited in areas affected by environmental toxicants.

Harmful effects of chemical and biological agents can include toxicants from pollutants, insecticides, pesticides, and fertilizers all of which can impact an organism and its community through shifts in species diversity and abundance. Resulting changes in population dynamics impact the ecosystem by altering its productivity and stability.

Legislation has been implemented since the early 1970s to ensure that harmful effects of environmental toxicants are minimized for all species. Unfortunalety, according to McCarty (2013[3]) we are facing the risk of entering in a "dark age" due to longstanding limitations in the implementation of the simple conceptual modes

Sources of environmental toxicity

There are many sources of environmental pesticides and biological agents, all of which can have harmful effects on living organisms.


Polychlorinated biphenyls (PCBs) are organic pollutants that are still present in our environment today despite being banned in many countries such as the United States and Canada. Due to the persistent nature of PCBs in aquatic ecosystems, many aquatic species contain high levels of this chemical.[3] For example, fish farmed salmon have been shown to have significantly higher PCB levels.[4]

Heavy metals

[4] 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 Cd excretion, and sustained growth under Cd exposure is evidence that shows that Chironomus riparius exhibits genetically based heavy metal tolerance.[5]


biomagnification within a food web. Pesticides can be categorized according to the pests they target. Insecticides are used to eliminate agricultural pests that attack various fruits and crops. Herbicides target herbal pests such as weeds and other unwanted plants that reduce crop production.


Dichlorodiphenyldichloroethylene (DDE) that were released into the environment were toxic to both animals and humans.[7]

DDT is not easily biodegradable and thus the chemical accumulates in soil and sediment runoff.[8] Water systems become polluted and marine life such as fish and shellfish accumulate DDT in their tissues.[8] Furthermore, this effect is amplified when animals who consume the fish also consume the chemical, demonstrating biomagnification within the food web.[8] The process of biomagnification has detrimental effects on various bird species because DDT and DDE accumulate in their tissues inducing egg-shell thinning.[7] Rapid declines in bird populations have been seen in Europe and North America as a result.[7]

Humans who consume animals or plants that are contaminated with DDT experience adverse health effects. Various studies have shown that DDT has damaging effects on the liver, nervous system and reproductive system of humans.[8]

By 1972, the United States Environmental Protection Agency (EPA) banned the use of DDT in the United States.[8] Despite the regulation of this pesticide in North America, it is still used in certain areas of the world. Traces of this chemical have been found in noticeable amounts in a tributary of the Yangtze River in China, suggesting the pesticide is still in use in this region.[9]

Sulfuryl fluoride

Sulfuryl fluoride is an insecticide that is broken down into fluoride and sulfate when released into the environment. Fluoride has been known to negatively affect aquatic wildlife. Elevated levels of fluoride have been proven to impair the feeding efficiency and growth of the common carp (Cyprinus carpio).[10] Exposure to fluoride alters ion balance, total protein and lipid levels within these fish, which changes their body composition and disrupts various biochemical processes.[10]



See also


  1. ^ http://www.biology.sfu.ca/degree/graduate/met
  2. ^ http://www.clemson.edu/entox/
  3. ^ McCarty, L.S. (Dec 2013). "Are we in the dark ages of environmental toxicology?". Regul Toxicol Pharmacol. 67 (3): 321–324. 
  4. ^ Bourret, V., Couture, P., Campbell, P.G.C., and Bernatchez, L. (2008). “Evolutionary ecotoxicology of wild yellow perch (Perca flavescens) populations chronically exposed to a polymetallic gradient.” Aquatic Toxicology. 86:76-90.
  5. ^ Bickham J.W., Sandhu S., Hebert P.D., Chikhi L., and Athwal R. (2000). “Effects of chemical contaminants on genetic diversity in natural populations: implications for biomonitoring and ecotoxicology.” Mutat Res. 463.1: 33-51.

Further reading

External links

  • Brief history of environmental toxicology