Environmental xenobiotic

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

Contents

Pharmaceuticals

Pharmaceutical drugs are chemicals used for the alteration, diagnosis, prevention and treatment of disease, health conditions or structure/function of the human body. Some pharmaceutically active compounds (PhACs) can enter the environment by one route or another as the parent compound or as pharmacologically active metabolites. Drugs are developed with the intention of having a beneficial biological effect on the organism to which they are administered, but many such compounds all too often pass into the environment where they may exert an unwanted biological effect. [1]

For many years PhACs have been all but ignored as environmental researchers concentrated on the well known environmentally dangerous chemicals that were/are largely used in agriculture and industry. But with increasing technology to help in the separation and identification of multiple compounds in a mixture, PhACs and their effects have received increasing attention. [2] PhACs have not (until relatively recently) been seen as potentially toxic because regulations associated with pharmaceuticals are typically overseen by human health organizations which have limited experience with environmental issues. [3]

Nearly all categories of pharmaceuticals including pain killers (analgesics and anti-inflammatory), antibiotics (antibacterial), anticonvulsant drugs, beta blockers, blood lipid regulators, X-ray contrast media, cytostatic drugs (chemotherapy), oral contraceptives, and veterinary pharmaceuticals among many others have been found in the environment. [4]

Sources and origins

PhACs can be entered into the environment in two main ways; direct and indirect. Indirect sources are PhACs that have performed their biologically intended effect and are passed onto the environment in either their complete or a modified state.

PhAC's can be discharged directly by manufacturers of the pharmaceuticals or effluents from hospitals. However with increasing regulation by local, state and federal regulating agencies, direct discharge is becoming much less of an issue. [4]

There are also several indirect sources of PhACs into the environment. One common indirect source of PhACs into the environment is the passing of antibiotics, anesthetics [2] and growth promoting hormones [5] by domesticated animals in urine and manure. This is often stored in large pits before being pumped and applied to fields as fertilizers where many of the PhACs can be washed away by rainfall to aquatic environments.

Family pets can also be an indirect source of PhACs into the environment. [2]

Most of the PhACs in the environment however come from human sources. A direct human source is leachate from a landfill. Often the pharmaceuticals that are located in landfills are found in their original, most chemically active state.

Most pharmaceuticals are administered and passed through the human body in one of three ways:

  1. Metabolized partially or completely within the body and made inactive (Ideal)
  2. Partially metabolized and passed through the system
  3. Passed through the body unmodified (Worst Case Scenario). In any manner PhACs are then passed to sewage treatment plants (STPs), where facilities are designed to break down natural human waste by microbial degradation. However, many PhACs are of very complex structure and are incompletely broken down in STPs before they are passed into the environment. [2]

Fate in environment

Once PhACs are entered into the environment they suffer one of three fates:

  1. Biodegradation into carbon dioxide and water.
  2. Undergo some form of degradation and form metabolites.
  3. Persist in the environment unmodified. The amount of the compound that is broken down depends on several factors such as bioavailability and compound structure among many others.

Effects

Because PhACs have come into the limelight relatively recently their effects on the environment are not completely understood. PhACs are also not generally intended to come in contact with the environment, and therefore are not typically tested environmentally prior to release. Therefore several tests are required to determine the different mechanisms and side effects of PhACs in the environment making testing largely impractical. [2]

Many PhACs have very broad modes of action in humans. Similar, subtle reactions may occur in organisms in the environment that are not easily seen by humans. Highly specific mechanisms in humans may solicit profound effects at extremely low concentrations. Many effects may not necessarily be readily detectable and lead to ecological change that would be erroneously attributed to natural change. [2] This said there are several effects that have been identified in the literature.

One long term, possibly irreversible effect is microbiological resistance to antibiotics (antibiotic resistance). Some bacteria may be able to survive when administered antibiotics (especially at low concentrations). [6] Those colonies will multiply and produce new colonies that are resistant to that particular antibiotic and will not succumb the next time antibiotics are administered. Because rivers and streams are ever flowing objects they are an ideal pathway for antibiotics to reach bacteria and therefore provide a source and reservoir for resistant strains to develop and establish themselves. [3]

Another recent discovery is endocrine disruptors. Endocrine disruptors can replace or disturb the balance of hormones within an organism and have been found to be occurring in waters with a concentration in the ng/L level for certain compounds. Some possible effects of endocrine disruptors are male and female sterility, feminization of males, masculinization of females and abnormal testes growth among many others. The exact pathway of occurrence of endocrine disruptors is not completely certain, however several pathways have been proposed. [6]

Typically PhACs are found in low concentrations, (<1 ug/L) making acute toxicity effects fairly unlikely. However, because of their continual input to the environment it is possible for chronic toxicity effects to occur. One major area of concern with several compounds being present at low levels at the same time is what happens when the compounds mix? It is possible and truly likely that these mixtures will have additive, neutralistic or synergistic effects. But again testing would be both time consuming and very expensive to test all of the combined effects.

Common pharmaceutically active compounds found in the environment

Analgesics (anti-inflammatory and antipyretic)

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

Antibiotics

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

Anticonvulsant

  1. Carbamazepine
  2. Primidone

Beta-blockers

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

X-ray media

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

Cytostatics (chemotherapy drugs)

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

Steroids and hormones

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

Related Research Articles

<span class="mw-page-title-main">Pharmacology</span> Science of drugs and medications and their effects

Pharmacology is the science of drugs and medications, including a substance's origin, composition, pharmacokinetics, pharmacodynamics, therapeutic use, and toxicology. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals.

Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance faster than it can be lost or eliminated by catabolism and excretion. Thus, the longer the biological half-life of a toxic substance, the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high. Bioaccumulation, for example in fish, can be predicted by models. Hypothesis for molecular size cutoff criteria for use as bioaccumulation potential indicators are not supported by data. Biotransformation can strongly modify bioaccumulation of chemicals in an organism.

<span class="mw-page-title-main">Medication</span> Substance used to diagnose, cure, treat, or prevent disease

A medication is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and relies on the science of pharmacology for continual advancement and on pharmacy for appropriate management.

<span class="mw-page-title-main">Water pollution</span> Contamination of water bodies

Water pollution is the contamination of water bodies, with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants mix with these water bodies. Contaminants can come from one of four main sources. These are sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. Water pollution may affect either surface water or groundwater. This form of pollution can lead to many problems. One is the degradation of aquatic ecosystems. Another is spreading water-borne diseases when people use polluted water for drinking or irrigation. Water pollution also reduces the ecosystem services such as drinking water provided by the water resource.

A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism. It can also cover substances that are present in much higher concentrations than are usual. Natural compounds can also become xenobiotics if they are taken up by another organism, such as the uptake of natural human hormones by fish found downstream of sewage treatment plant outfalls, or the chemical defenses produced by some organisms as protection against predators. The term "xenobiotic" is also used to refer to organs transplanted from one species to another.

<span class="mw-page-title-main">Endocrine disruptor</span> Chemicals that can interfere with endocrine or hormonal systems

Endocrine disruptors, sometimes also referred to as hormonally active agents, endocrine disrupting chemicals, or endocrine disrupting compounds are chemicals that can interfere with endocrine systems. These disruptions can cause numerous adverse human health outcomes, including alterations in sperm quality and fertility; abnormalities in sex organs‚ endometriosis‚ early puberty‚ altered nervous system or immune function; certain cancers; respiratory problems; metabolic issues; diabetes, obesity, or cardiovascular problems; growth, neurological and learning disabilities, and more. Found in many household and industrial products, endocrine disruptors "interfere with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body that are responsible for development, behavior, fertility, and maintenance of homeostasis ."

<span class="mw-page-title-main">Bisphenol A</span> Chemicals used in plastics manufacturing

Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on an industrial scale by the condensation reaction of phenol and acetone. Global production in 2022 was estimated to be in the region of 10 million tonnes.

<span class="mw-page-title-main">Persistent organic pollutant</span> Organic compounds that are resistant to environmental degradation

Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes. They are toxic and adversely affect human health and the environment around the world. Because they can be transported by wind and water, most POPs generated in one country can and do affect people and wildlife far from where they are used and released.

<span class="mw-page-title-main">Nonylphenol</span> Chemical compound

Nonylphenols are a family of closely related organic compounds composed of phenol bearing a 9 carbon-tail. Nonylphenols can come in numerous structures, all of which may be considered alkylphenols. They are used in manufacturing antioxidants, lubricating oil additives, laundry and dish detergents, emulsifiers, and solubilizers. They are used extensively in epoxy formulation in North America but its use has been phased out in Europe. These compounds are also precursors to the commercially important non-ionic surfactants alkylphenol ethoxylates and nonylphenol ethoxylates, which are used in detergents, paints, pesticides, personal care products, and plastics. Nonylphenol has attracted attention due to its prevalence in the environment and its potential role as an endocrine disruptor and xenoestrogen, due to its ability to act with estrogen-like activity. The estrogenicity and biodegradation heavily depends on the branching of the nonyl sidechain. Nonylphenol has been found to act as an agonist of the GPER (GPR30).

Xenoestrogens are a type of xenohormone that imitates estrogen. They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens include some widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estrogenic effects on a living organism even though they differ chemically from the estrogenic substances produced internally by the endocrine system of any organism. Natural xenoestrogens include phytoestrogens which are plant-derived xenoestrogens. Because the primary route of exposure to these compounds is by consumption of phytoestrogenic plants, they are sometimes called "dietary estrogens". Mycoestrogens, estrogenic substances from fungi, are another type of xenoestrogen that are also considered mycotoxins.

<span class="mw-page-title-main">Triclocarban</span> Antimicrobial agent

Triclocarban is an antibacterial chemical once common in, but now phased out of, personal care products like soaps and lotions. It was originally developed for the medical field. Although the mode of action is unknown, TCC can be effective in fighting infections by targeting the growth of bacteria such as Staphylococcus aureus. Additional research seeks to understand its potential for causing antibacterial resistance and its effects on organismal and environmental health.

<span class="mw-page-title-main">Ecotoxicity</span>

Ecotoxicity, the subject of study in the field of ecotoxicology, refers to the biological, chemical or physical stressors that affect ecosystems. Such stressors can 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.

<span class="mw-page-title-main">Environmental impact of pharmaceuticals and personal care products</span> Effects of drugs on the environment

The environmental effect of pharmaceuticals and personal care products (PPCPs) is being investigated since at least the 1990s. PPCPs include substances used by individuals for personal health or cosmetic reasons and the products used by agribusiness to boost growth or health of livestock. More than twenty million tons of PPCPs are produced every year. The European Union has declared pharmaceutical residues with the potential of contamination of water and soil to be "priority substances".[3]

Xenohormones or environmental hormones are compounds produced outside of the human body that exhibit endocrine hormone-like properties. They may be either of natural origin, such as phytoestrogens, which are derived from plants, or of synthetic origin. These compounds can cause endocrine disruption by multiple mechanisms including acting directly on hormone receptors, affecting the levels of natural hormones in the body, and by altering the expression of hormone receptors. The most commonly occurring xenohormones are xenoestrogens, which mimic the effects of estrogen. Other xenohormones include xenoandrogens and xenoprogesterones. Xenohormones are used for a variety of purposes including contraceptive & hormonal therapies, and agriculture. However, exposure to certain xenohormones early in childhood development can lead to a host of developmental issues including infertility, thyroid complications, and early onset of puberty. Exposure to others later in life has been linked to increased risks of testicular, prostate, ovarian, and uterine cancers.

<span class="mw-page-title-main">Environmental persistent pharmaceutical pollutant</span> Environmental term

The term environmental persistent pharmaceutical pollutants (EPPP) was first suggested in the nomination in 2010 of pharmaceuticals and environment as an emerging issue in a Strategic Approach to International Chemicals Management (SAICM) by the International Society of Doctors for the Environment (ISDE). The occurring problems from EPPPs are in parallel explained under environmental impact of pharmaceuticals and personal care products (PPCP). The European Union summarizes pharmaceutical residues with the potential of contamination of water and soil together with other micropollutants under "priority substances".

Sex is influenced by water pollutants that are encountered in everyday life. These sources of water can range from the simplicity of a water fountain to the entirety of the oceans. The pollutants within the water range from endocrine disruptor chemicals (EDCs) in birth control to Bisphenol A (BPA). Foreign substances such as chemical pollutants that cause an alteration of sex have been found in growing prevalence in the circulating waters of the world. These pollutants have affected not only humans, but also animals in contact with the pollutants.

Toxicodynamics, termed pharmacodynamics in pharmacology, describes the dynamic interactions of a toxicant with a biological target and its biological effects. A biological target, also known as the site of action, can be binding proteins, ion channels, DNA, or a variety of other receptors. When a toxicant enters an organism, it can interact with these receptors and produce structural or functional alterations. The mechanism of action of the toxicant, as determined by a toxicant’s chemical properties, will determine what receptors are targeted and the overall toxic effect at the cellular level and organismal level.

Drug pollution or pharmaceutical pollution is pollution of the environment with pharmaceutical drugs and their metabolites, which reach the aquatic environment through wastewater. Drug pollution is therefore mainly a form of water pollution.

Contaminants of emerging concern (CECs) is a term used by water quality professionals to describe pollutants that have been detected in environmental monitoring samples, that may cause ecological or human health impacts, and typically are not regulated under current environmental laws. Sources of these pollutants include agriculture, urban runoff and ordinary household products and pharmaceuticals that are disposed to sewage treatment plants and subsequently discharged to surface waters.

<span class="mw-page-title-main">Despo C. Fatta-Kassinos</span> Chemical and environmental engineer, academic and author

Despo C. Fatta-Kassinos is a chemical and environmental engineer, academic and author. She is a professor in the Department of Civil and Environmental Engineering and the first director of Nireas-International Water Research Center (Nireas-IWRC) at the University of Cyprus (2010–2022). She has been named a Highly Cited Researcher by Web of Science, Clarivate Analytics.

References

  1. ↑ Halling-Sorensen et al. 1998. Occurrence, fate, and effects of pharmaceutical substances in the environment-A Review. Chemosphere 36: 357-393
  2. 1 2 3 4 5 6 Daughton and Ternes. 1999. Pharmaceuticals and personal care products in the environment: Agents of subtle change? Environmental Health Perspectives 117:907-938.
  3. 1 2 Jones et al. 2001. Human pharmaceuticals in the aquatic environment. Environmental Technology 22: 1383-1394
  4. 1 2 Heberer. 2002. Occurrence, fate and removal of pharmaceutical residues in the aquatic environment- A review of recent research data. Toxicology Letters 131: 5-17.
  5. ↑ Bound and Voulvoulis. 2004. Pharmaceuticals in the aquatic environment- A comparison of risk assessment strategies. Chemosphere 56: 1143-1155.
  6. 1 2 Jorgenson and Halling-Sorensen. 2000. Drugs in the Environment. Chemosphere 40: 691-699.
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