08-23-2021-1059 - Environmental Xenobiotics

Environmental xenobiotics are xenobiotic compounds with a biological activity that are found as pollutants in the natural environment. 

Common pharmaceutically active compounds found in the environment[edit]

Analgesics (anti-inflammatory and antipyretic)[edit]

1. Acetaminophen
2. Acetylsalicylic Acid
3. Diclofenac
4. Codeine
5. Ibuprofen

Antibiotics[edit]

1. Macrolide Antibiotics
2. Sulfonamides
3. Fluoroquinolones
4. Chloramphenicol
5. Tylosin
6. Trimethoprim
7. Erythromycin
8. Lincomycin
9. Sulfamethoxazole
10. Trimethoprim

Anticonvulsant[edit]

1. Carbamazepine
2. Primidone

Beta-blockers[edit]

1. Metoprolol
2. Propanolol
3. Betaxolol
4. Bisoprolol
5. Nadolol

X-ray media[edit]

1. Iopromide
2. Iopamidol
3. Iohexol
4. Diatrizoate

Cytostatics (chemotherapy drugs)[edit]

1. Cyclophosphamide
2. Mycophenolic acid
3. Ifosfamide
4. Bicalutamide
5. Epirubicin

Steroids and hormones[edit]

1. 17α-ethinylestradiol
2. Mestranol
3. 19-norethisterone

https://en.wikipedia.org/wiki/Environmental_xenobiotic

Xenobiotic substances are an issue for sewage treatment systems, since they are many in number, and each will present its own problems as to how to remove them (and whether it is worth trying to)

Some xenobiotics substances are resistant to degradation. Xenobiotics such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons(PAHs), and trichloroethylene (TCE) accumulate in the environment due to their recalcitrant properties and have become an environmental concern due to their toxicity and accumulation. This occurs particularly in the subsurface environment and water sources, as well as in biological systems, having the potential to impact human health.^[7] Some of the main sources of pollution and the introduction of xenobiotics into the environment come from large industries such as pharmaceuticals, fossil fuels, pulp and paper bleaching and agriculture.^[8] For example, they may be synthetic organochlorides such as plastics and pesticides, or naturally occurring organic chemicals such as polyaromatic hydrocarbons (PAHs) and some fractions of crude oil and coal.

Microorganisms may be a viable solution to this issue of environmental pollution by the degradation of the xenobiotics; a process known as bioremediation.^[9] Microorganisms are able to adapt to xenobiotics introduced into the environment through horizontal gene transfer, in order to make use of such compounds as energy sources.^[8] This process can be further altered to manipulate the metabolic pathways of microorganisms in order to degrade harmful xenobiotics under specific environmental conditions at a more desirable rate.^[8] Mechanisms of bioremediation include both genetically engineering microorganisms and isolating the naturally occurring xenobiotic degrading microbes.^[9] Research has been conducted to identify the genes responsible for the ability of microorganisms to metabolize certain xenobiotics and it has been suggested that this research can be used in order to engineer microorganisms specifically for this purpose.^[9] Not only can current pathways be engineered to be expressed in other organisms, but the creation of novel pathways is a possible approach.^[8]

Xenobiotics may be limited in the environment and difficult to access in areas such as the subsurface environment.^[8] Degradative organisms can be engineered to increase mobility in order to access these compounds, including enhanced chemotaxis.^[8] One limitation of the bioremediation process is that optimal conditions are required for proper metabolic functioning of certain microorganisms, which may be difficult to meet in an environmental setting.^[7] In some cases a single microorganism may not be capable of performing all metabolic processes required for degradation of a xenobiotic compound and so “syntrophic bacterial consortia” may be employed.^[8] In this case, a group of bacteria work in conjunction, resulting in dead end products from one organism being further degraded by another organism.^[7] In other cases, the products of one microorganisms may inhibit the activity another, and thus a balance must be maintained.^[8]

Many xenobiotics produce a variety of biological effects, which is used when they are characterized using bioassay. Before they can be registered for sale in most countries, xenobiotic pesticides must undergo extensive evaluation for risk factors, such as toxicity to humans, ecotoxicity, or persistence in the environment. For example, during the registration process, the herbicide, cloransulam-methyl was found to degrade relatively quickly in soil.^[10]

https://en.wikipedia.org/wiki/Xenobiotic

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