What is the problem?

What is the problem?

This illustration shows how antibiotics used for human and livestock are are able to cycle through the environment and end up in our marine environments and eventually back to humans and livestock.

In 1928, Alexander Fleming discovered that the mold juice he had extracted from mouldy bread was able to inhibit the growth of certain disease causing bacteria, thus leading to the discovery of the first recognized antibiotic penicillin[1]. Since Fleming, the development of antibiotics has significantly progressed and the majority of antibiotics, if not all, now contain synthetic properties. Naturally derived antibiotics such as those discovered by Flemings were degradable as they essentially came from foods and would be broken down over time, however with modern synthetic antibiotics, they continue to persist in the environment and are increasingly causing problems for not only our ecosystems, but human health[2]. Some of these problems include the emergence of antibiotic-resistant strains of bacteria, degradation of water quality in both drinking water and coastal waters, and severe population loss of wildlife[2].

What human actions cause the problem?

Much of the antibiotics produced today are used for human consumption in order to treat a variety of illnesses as well as for agricultural purposes. From here, there are multiple ways in which antibiotics or its remnants can enter our marine ecosystems.[3] Often times, people end up flushing their antibiotics down the drain and these inappropriate disposals can end up in pipes that lead out to our bodies of water[3]. In regards to agricultural purposes, antibiotics are used to treat and prevent disease in livestock as well as help their growth.[4] The antibiotic remnants in livestock feces makes its way into coastal waters, ultimately also contributing to degradation of quality in our waters as well as antibiotic resistance[4]. In addition to that, humans produce an alarming amount of plastic pollution that ends up in the marine ecosystems and in turn, these plastic waste materials become reservoirs for antibiotics due to their high absorption abilities, enabling antibiotics to travel further in the waters[5].

Where does the problem occur?

Many of the studies carried out by scientists were placed in developing countries as these countries lack the resources to obtain technology and equipment that effectively contain the spread of antibiotics into our marine ecosystems. For example, in a study carried out in Baghdad Iraq, water samples were taken from two water treatment plants to measure the amount of the antibiotics ciprofloxacin, levofloxacin, and amoxicillin, present in the water pre/post-treatment. It was found that post-treatment water still contained considerable amounts of ciprofloxacin and levofloxacin, in which these antibiotics could and will eventually end up in coastal waters.[2] A research conducted in 72 countries concluded that 65% of these countries had waters that contained antibiotics and out of the 65%, lower income countries like Africa and China held the highest percentage with Africa boasting 35% of it’s rivers having tested positive for exceeding safe concentration limits of antibiotics[6].

How pervasive is the problem?

Due to the fact that antibiotics are originally designed to alter specific biological activities in order to be effective in the treatment of diseases, it can cause immediate acute toxicity on organisms that come into contact.[7] If concentrations of antibiotics in the water are high enough, it could lead to a mass population crash of organisms that reside in the affected body of water, although more studies need to be conducted to further develop this analysis[7].

How does Antibiotic pollution impact marine ecosystems?

Extent and cause of antibiotic pollution in marine ecosystems

Antibiotic pollution can have widespread effects on marine ecosystems, impacting many levels of the food chain including microbial organisms, algae, invertebrates and fish[8] . The aquatic environment is specifically susceptible to antibiotic pollution since it is a large sink for contaminants from human activities[9], many residual chemicals make their way into the ecosystem as parent molecules (precursors to the residual chemicals) or products of metabolism [10]. This constant discharging of antibiotics into aquatic environments leads to persistent pollution[10].

How antibiotic pollution effects marine organisms

One of the main groups affected by antibiotic pollution are microbial communities, which can be affected by antibiotics in a wide range of ways. Antibiotics have the capacity to inhibit protein synthesis and chloroplast development in some aquatic photosynthetic autotrophs (microalgae and cyanobacteria). This causes the photosynthetic capabilities of these organisms to be affected, leading to growth inhibition[10] . Furthermore, certain members within bacterial species have different phenotypic responses to antibiotic stressors, due to the fact that antibiotics can affect bacterial enzyme activity[8]. This diversity in response can cause certain organisms to be favored based on their phenotypes[8].

Figure (1) shows the relative abundance of bacterial groups that were isolated from the intestines of OTC medicated Atlantic salmon (tanks 1 & 2) and untreated salmon (control). Results are taken 1, 11, 18 and 25 days after treatment  (Navarrete et al., 2008). The results show that the medicated tanks had lower species diversity.[11]

Antibiotic pollution in marine ecosystems can also affect larger organisms, specifically antibiotic pollution has been seen to have a negative effect on vertebrates. For example, the addition of macrolides (a certain group of antibiotics) has been found to affect embryo movement as well as induce deformities in zebrafish (scoliosis and hatching rate)[12]. Additionally, the microbiome of larger organisms can be affected by antibiotics, a study done by Navarrete et al. (2008) found that treatments of antibiotic Oxytetracycline (OTC) reduced bacterial diversity in the intestines of Atlantic salmon compared to untreated salmon (figure (1))[11]. The results of this study supported the hypothesis that antibiotic pollution can lead to the elimination of some bacteria, allowing different bacterial species to dominate.

Bacterial vulnerability to antibiotics

Usually, the populations that will become dominant in a polluted ecosystem will be those that are resistant or tolerant to the antibiotics present[8] (known as gram negative bacteria). Certain bacteria are more susceptible to antibiotics and disinfectants because they lack an outer cell membrane, these bacteria are known as gram positive[8]. The exposure of these gram positive bacteria to pollutants may result in the mortality of bacterial lineages that are important for the food web[13]. In fact, antibiotic presence in aquatic ecosystems was found to be a driving force behind the reduction of microbial organisms that were responsible for primary productivity and carbon cycling[8]. It has also been found that antibiotic pollution can lead to the increase in toxic cyanobacteria[8] .

What is the extent of the problem?

What are the measurable ecosystem changes that have occurred?

Currently there are over 36 different types of antibiotics that are frequently detected in China's coastal waters and it was found that many of these 36 detected antibiotics have caused acute toxicity in species of phytoplankton[14]. Phytoplankton are one of the most predominant components that make up the base of the food web, and therefore if affected, could cause critical bottom-up on organisms that are higher up the food chain[15].

What is the present status compared to the past?

Since the introduction of synthetic properties incorporated into the synthesis of antibiotics, the rapid rise of antibiotic pollution has become a pressing issue as it has various ways of affecting humans and wildlife, both indirectly and directly[16]. Just within a 10 year span, antibiotic use was up by 65%, parallel with the rapid increase of antimicrobial resistance seen in marine organisms and subsequently humans[3]. For example, the rate of resistance to the antibiotic ciprofloxacin, an antibiotic used to treat urinary tract infections, has increased from 8.4% to 92.9% as of current[17]. In the past, species of environmental bacteria such as Vibrio were generally susceptible to antibiotic treatments, however, in recent years it has been reported that they have seemed to develop a resistance to at least one or two types of antibiotics. Vibrosis is a disease that affects around 85,000 people per year in the United States and by 2017, it has been concluded that 2.8 million people worldwide each year contract antibiotic-resistant cholera. It is hypothesized that the recent rise in antibiotic resistance of vibrio is due to factors surrounding antibiotics being used in treating livestock that is eventually consumed by humans. In a study done on farmed marine shrimps, it was found that the shrimps treated with antibiotics eventually developed and tested positive for antibiotic resistance genes in which the genes are able to transfer to humans through consumption[18].

What is the prognosis for the future if we continue on our current trajectory?

Moving forward, antibiotic pollution will continue to become a persistent issue as there isn’t a feasible plan that will enable all bodies of water to be effectively treated and rid of antibiotic residue. Taking into consideration the economical status of multiple countries, it is not possible to provide every single country with the proper equipment to combat such problems and so continually antibiotic pollution in water will remain[19]. The only thing as of right now that we can continue to do is research into alternative options that will enable countries to compensate for the effects of antibiotics in the water as opposed to actively getting rid of the pollution. If rising levels of antibiotic pollution continue, there will be equivalent numbers of rising antibiotic resistance bacteria that could lead to the widespread antibiotic resistance in humans. If we are unable to develop measures that could treat such changes, many lives could be at risk in terms of health and disease.

Given the impact, what are the solutions?

What are the local solutions, if any?

Image 1. Shows a visual of the process of Axine’s solution and how it cleans the contaminated wastewater from factories.[20]

Solutions to tackle antibiotic contamination in marine habitats are ongoing and researchers have been coming up with rules for quite a while now. In Vancouver, British Columbia (Canada), there is a company that has found a solution for getting rid of the wastewater that comes out of pharmaceutical companies. These pharmaceutical factories need water just like any other manufacturing company, for example to clean equipment between batches. Then, that water gets contaminated and ends up at sewage-treatment plants that do not have the right tools to break it down and properly clean the water[21]. The company, called Axine Water Technologies, found that when electrodes with advanced catalyst materials are applied with electricity, they can produce an oxidant on the surface of the catalyst. This generates one oxygen and one hydrogen, making what is called a hydroxyl radical, which is very reactive[21]. Then, the wastewater is flowed through these catalysts and the hydroxyl radicals react with the organic pollutants in the water, properly breaking the molecules down and oxidizing them back to their basic molecules (Oxygen, hydrogen and nitrogen gas) (Image 1)[21]. Once the water has been treated, it can be safely reused at the factory again or go to the sewer. This new solution also provides no waste products. One hurdle that must be overcome is the fact that wastewater varies with each pharmaceutical factory, however, the Axine system has a broad range for treatment and can even treat wastewater from electronics and chemical facturing[21]. In British Columbia, 6 companies have started using Axine’s solution (Image 2).

Image 2. Shows Axine’s solution system for the wastewater at a pharmaceutical factory.[20][21]

What are the global solutions, if any?

Globally, countries have different levels of antibiotic pollution in their rivers because of different reasons, however they have different, but very common solutions. In China, the antibiotic pollution is because of two main issues: misuse of antibiotics in medical and livestock industries and the antibiotics in the waste of pharmaceutical companies[22]. At the time the article was written, there was no requirement to test the tap water for antibiotics, thus implying that some steps have not been taken. However, they suggested that China improve their laws and regulations strictly so that they can control the antibiotic pollution in their water and from pharmaceutical factories and hospitals[22]. Though those previous examples targeted solutions for specific countries/places, researchers have also been looking for scientific ways to solve the antibiotic problem. In one study, Pruden et al.[23] suggested routine monitoring programs so researchers can keep up with the antibiotic pollution rates and find out how to stop them. In another study, it was found that when manure was tended to with high-intensity management (amending, watering, or turning), the antibiotics depleted more rapidly than the manure that was tended to with lower-intensity management (none of the previously listed)[24]. Wastewater has also been reused as a strategy for water sustainability[23] with some studies using chlorination, UV waves[25] and pH[26] to reduce the antibiotics in water and wastewater.


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