Project Summary

 Contaminants of Emerging Concern as Major Public Health Challenges

The presence of unregulated and unmonitored contaminants, called Contaminants of Emerging Concern (CECs), at low concentrations (µg/L and sub-µg/L) in surface, ground, and drinking water is becoming an increasing concern for the scientific communities and the public in general. They include different varieties of pharmaceuticals, personal care products (PCPs), debris of microplastics (MPs), flame retardants (FRs), pesticides, and artificial sweeteners (ASWs). The existence of all living organisms, including human beings, depends on the overall condition of the environment. The more all its parts become clean the more all the living organisms can exist healthy and possibly longer life expectancy. However, what is happening on the ground is the reverse. Plenty of waste products are disposed to our beautifully and well-designed environment continuously in solid, liquid, and gaseous forms. We human beings are the main actors for the depletion of every part of the ecosystem either directly or indirectly. You can observe the water streams, the roads, or any environmental systems including the atmosphere when you walk, drive, or during your flight. Take a picture of it and start to think about the sources, the destination of all the waste products, and the types of effects they could pose. For sure, you will be deeply saddened and shocked by what we human beings are doing! You will easily understand how we are preparing our own suicide weapons!

As a tip of an iceberg, see video 1, which was taken during my walk on 10^th October 2023 alongside the Dublin Road from University of Limerick to the Limerick City Centre, just between Travelodge and Supermacs or Maxol, Castletroy, Co. Limerick. Everyone can guess the destination of this water stream containing those plenty of liquid waste products suspended over the surface of the water. Once it is included in Shannon River, fish and other aquatic organisms are the direct vulnerable followed by indirect intake by human beings and other organisms. If so, what do you think about human health for the coming couple of years if there is no effective controlling mechanism of treatment of waste chemical contaminants?

Video 1:  Liquid wastes originated from unknown sources flowing through a water stream to the River Shannon. Location: between Travelodge and supermacs/Maxol, Castletroy, Co. Limerick.

Pharmaceutical Waste Products

Currently, the disposal of unused, expired, and contaminated pharmaceutical products including antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), endocrine-disrupting compounds (EDCs), and others to the environment is the hottest concern of researchers and the community at large. They are continuously disposed from pharmaceutical manufacturing plants, health care institutions and extended care facilities, personal care product manufacturers, veterinary offices, pharmaceutical research centers, hospitals, pharmacies, distribution centers, and households to the environment in each second at each corner of the world without sufficient treatment, pass through different routes, and incorporated into different water systems, which could then develop other secondary chronic contaminants (Fig. 1).

Fig. 1: Distribution and uptake routes of Antibiotics and Antibiotic Resistant Bacteria, respectively.

Antimicrobial resistance is developed when germs including bacteria and fungi develop the ability to defeat the drugs designed to kill them and continue to grow and reproduce. As depicted in Fig.2, when antibiotics are disposed to the system comprising high population of bacteria, some of them can be killed, and the rest become mutated and multiply to the highest level of maxima, where their antibiotic resistant nature is genetical and transferable to the nearby bacteria. This is to mean that a person affected by those antibiotic resistant bacteria (ARB) cannot be cured any more using the commercially available antibiotic drugs.

Fig. 2: Drug resistant bacteria and their distribution

Let us think of long-flowing rivers of River Shannon and Abay River from Ireland and Ethiopia, respectively. These rivers have their own tributaries from different sources. For the case of River Shannon, think about Video 1 above, which comprises different liquid waste products that could also possibly include pharmaceuticals from different sources, and all these have been added into the river. Finally, the river carries all these and incorporated to North Atlantic Ocean, where many organisms including fish become directly susceptible. As an Ethiopian, I know Abay River, commonly known as Blue Nile. It originates at Sekela Woreda (ሰከላ ወረዳ), West Gojjam Zone, and comprises different tributaries including Serja (ሰርጃ), Jema (ጀማ), Ashar (አሻር), and other rivers and almost it rotates the country. It gets out the country via Sudan and joined another big river there, White Nile. Finally, it passes through Egypt and included to Mediterranean Sea.  Imagine how much waste pharmaceutical products in completely dissolved and particulate forms it carries throughout its path. Think how many domestic and wild animals, other organisms, and people have been affected at each point in its path. It is a clear implication that the infection of River Shannon or Blue Nile at its origin affects not only the nearby communities but also the whole communities worldwide.   

In general, mismanagement of pharmaceutical products leads to formation of Antibiotic Resistant Bacteria and Antibiotic Resistant Genes, or get back to the human body systems, and finally pose sub-lethal and lethal impacts at a very low level of exposure. The main reasons that the people discard these contaminants to the environment without effective treatment are (1) poor pharmaceutical waste management practices, (2) lack of training and awareness, (3) users’ resistance, poor managerial commitment, negligence, unfavorable attitude towards waste management, and (4) lack of adequate resources or technologies.

Ciprofloxacin

Ciprofloxacin is an antibiotic, which is only available on prescription. It belongs to a group of antibiotics called fluoroquinolones. It works by killing the bacteria that causes infections including uncomplicated urinary tract infections, chest infections, skin and bone infections, sexually transmitted infections, conjunctivitis, eye infections, and ear infections. It is also used to help prevent people getting meningitis if they have been in close contact with someone with the infection. It comes as tablet and liquid forms.

According to the “Selection of substances for the 3^rd Watch List under the Water Framework Directive” report, ciprofloxacin (Fig.2) is one of the antibiotics that have potential concerns in the aquatic environment. Residual ciprofloxacin in the environment has become an emerging micropollutant that promotes the generation of resistance genes of bacteria and endangers ecosystem balance and human health. The stable chemical structure makes it difficult to be removed by conventional techniques including adsorption and membrane filtration. These techniques are for only transfer of pollutants and do not degrade rather leaving them behind as sources of secondary contaminants. Hence, a more advanced approach is mandatory, semiconductor-based photodegradation approach. This method is preferable compared to the others since it requires less and environmentally friendly chemical inputs for photocatalyst development and degradation of Ciprofloxacin and other pharmaceutical products.

Fig.2: (a) 2-D and (b) 3-D structures of ciprofloxacin