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A Focus on Active Chemicals in Sub-Saharan Africa

Active chemicals are among the contaminants of emerging concern that are rarely covered in regulatory documents in sub-Saharan Africa. 

  • Active chemicals (ACs)
  • Pharmaceutical load
  • Sub-Saharan Africa (SSA)
  • Environmental Toxicology
  • Drug-drug interactions
  • Wastewater
  • Mixture
  • Contaminants

1. Environmental Effects of Active Chemicals

The existence of different categories of active chemicals in the environmental matrices has been reported in some sub-Saharan African countries. These reports indicate the presence of the active chemicals, and point to a possibility of the ACs causing harm not only to human health but also to the natural environment. Most drugs reported were anti-inflammatories, antibiotics, antiretroviral drugs, analgesics, psychiatric treatment drugs, steroid hormones, diabetes treatment drugs, or hypertension drugs. Loads of active chemicals released into the environment after human, animal, and agricultural usage have been linked to both human and environmental health degradation. Although active chemicals are considered to be contaminants of emerging concern, they are currently neither monitored nor included in the environmental guidelines.
Chemicals that are environmentally persistent and have a tendency to bioaccumulate pose a great potential for environmental risk, especially when such chemicals come into contact with drinking water supplies and the food chain [1][2][3]. Various scholars have reported the effects of these substances and their potential for harm, including the development of AMR [4][5][6][7], as well as effects on the sex of aquatic organisms [8][9][10][11][12][13][14]. The early years of research in the area of the effects of ACs placed more emphasis on the assessment of the acute effects as a result of individual substances, largely ignoring the effects that may be caused by combinations of these substances. Recently, however, there has been a shift in focus to chronic exposure and the assessment of the effects of drug mixtures [12][14][15][16]. It is important to study drug mixtures—commonly described as a ‘cocktail effect’—including drug-drug interactions leading to adverse effects. Usually, human subjects receive a prescription with instructions on how to properly use drug mixtures. For instance, patients should not mix ibuprofen with beta-blockers, or opioids with alcohol. However, other organisms in the ecosystem do not receive instructions from medical doctors. As a result, a fish reeling in an effluent containing a mixture of drugs and other contaminants in a polluted river will simply succumb to the adverse effects thereof.

2. Environmental Load of Active Chemicals

Active chemicals are now some of the main environmental pollutants and are abundant in water, soils, and other environmental media. Environmental risk assessment and routine environmental monitoring regulations do not include active chemicals, simply because acute risk assessments show insignificant human health hazards. However, the drawbacks of active chemicals extend beyond acute effects to delayed effects from bioaccumulation, amplified effects from drug-drug interactions, aggravation of drug resistance, and reduction in aquatic and terrestrial food production; this merits serious measures for public health protection [17]. Reports on the presence of active chemicals in the sub-Saharan African environment are still scarce, with only a few countries reporting [18][19], indicating a need for more research. Therefore, this review will aid in providing data that are necessary to indicate the presence and possible harm of active chemicals in the sub-Saharan African environment, and to inform current and future policymaking processes.

Occurrences of Active Chemicals in Other Parts of Africa

Apart from sub-Saharan African countries, South Africa is among the African countries with greater awareness and practice concerning environmental protection [18][20][21][22][23]. In most developed countries, the use of active chemicals is higher; thus, the load to the environment may also be higher. Occurrences of active chemicals in the South African environmental compartments are presented in Table 1. Additionally, research [24], has reported that pollutants arise not only from waste products but also from pharmaceutical products that have not been properly disposed of. The continuous exposure to unspecified sub-therapeutic doses of antibiotics presents a risk to humans and other animals.
Table 1. Occurrences of ACs in the South African environmental compartments.
Matrix Substance (s) Concentration (ng/L) References
Wastewater Clarithromycin 5–30 [23]
Erythromycin 10–100
Sulfadimidine 0–10
Sulfamethoxazole 5–1000
Sulfapyridine 5–110
Chlortetracycline 90
Oxytetracycline 100
Trimethoprim 5–10,000
Seawater Ibuprofen 160 [20]
Naproxen 160
Wastewater Nevirapine and efavirenz 2100 ng/L
17,400 ng/L
Wastewater Ibuprofen 117,000  
Surface water 84,600 [26]
Sediments 65,900  
Water Concentrations were efavirenz > nevirapine > carbamazepine > methocarbamol > bromacil > venlafaxine. 164–593 [27]
Surface water Antiretrovirals (ARVs) 26.5–430 [28]

3. Active Chemicals in the Sub-Saharan African Context

Information on the occurrence of quantifiable levels of active chemicals in the sub-Saharan African environment is lacking. It is known that therapeutic consumption of active chemicals to promote human health is usually followed by excretion of these drugs via urine or fecal matter, due to their slight alteration of the human metabolism. The detection of several active chemical classes—including nonsteroidal anti-inflammatories, antibiotics, antiretrovirals, anti-epileptics, steroid hormones, and anti-malarial drugs—has been reported in water resources, influents, and effluents in some countries in sub-Saharan Africa [18][20][29][30]. Moreover, general investigation and monitoring of active chemicals in different sub-Saharan African countries are required, and the necessary instrumentation for their trace quantification in environmental samples should be made available.

3.1. Kenya

Reports of the presence of active chemicals in the Kenyan environment are available [31][32][33]. Some exclusive data on the concentrations and loads of chemicals such as antibiotics, antivirals, analgesics, anti-inflammatories, and psychiatric drugs are presented in Table 2.
Table 2. Occurrences of ACs in the Kenyan environmental compartments.
Substances Effluents Surface Water (ng/L) Sediments (ng/Kg) References
Norfloxacin 4.2 1.6 to 4.9 248 to 776 [33]
Trimethoprim 15.8 3.8 to 4.4 11 to 90
Ciprofloxacin 5.3 2.5 to 2.8 4125 to 1225
Sulfamethoxazole 956.4 96.9 to 142.6 542 to 896
Lamivudine 847.1 219.6 to 228.3 107 to 491
Zidovudine 1.4 1.1 to 21 118 to 510
Clavulanic acid 10–110     [23]
Erythromycin 100–150    
Sulfadimidine 0–5    
Sulfamerazine 2–20    
Minocycline 0    
Tetracycline 10–180    
Trimethoprim 5–100    
Lincomycin 5–80  

3.2. Uganda

The presence of quantifiable levels of active chemicals was investigated in Uganda’s environmental compartments [34][35][36]. The results indicate the presence of active chemicals belonging to multiple therapeutic categories, as presented in Table 3.
Table 3. Occurrences of ACs in the Ugandan environmental compartments.
Matrix Substance Concentration (ng/ L) References
Lake Victoria water Sulfamethoxazole 1–5600 [35]
Trimethoprim 1–89 L
Tetracycline 3–70
Sulfacetamide 1–13
Erythromycin 10–66
Sulfamethazine 2–50
Carbamazepine 5–72
Ibuprofen 6–780
Diclofenac 2–160
Sulfamethoxazole 1–5600

3.3. Tanzania

In Tanzania, as in other sub-Saharan countries, wastewater treatment plants are not designed for the removal of emerging contaminants such as active chemicals. Wastewater stabilization ponds are utilized to partially treat the effluents from industries, residential areas, and hospitals. Therefore, when effluents are released into the ecosystem, the chemical load is increased [37][38][39][40][41][42][43]. Occurrences of the active chemicals in the Tanzanian environment are presented in Table 4.
Table 4. Occurrences of ACs in the Tanzanian environmental compartments.
Matrix Substance Concentration References
Wastewater Metronidazole 0.065–0.104 ppm [40]
Msimbazi River waters Metronidazole 0.0024 ppm  
Paracetamol 0.0060 ppm [42]
Cetirizine 0.0073 ppm  
Ibuprofen 0.0016 ppm  
Wastewater effluents Ampicillin bdl to 0.367 ppm [37]
Ciprofloxacin bdl to 0.037 ppm  
AMR Lake Victoria water Sulfamethoxazole/trimethoprim 100% [41]
Ampicillin/cloxacillin 100%
Erythromycin 72.7%
Tetracycline 90.9%
Nalidixic acid 63.6%

3.4. Zambia

According to the available information, Zambia’s environmental compartments were mostly affected by the presence of active chemicals from the classes of antibiotics and antivirals, as presented in Table 5. Although the industrial release of these contaminants is possible, a report indicated only the presence of metalloid toxicants [44]. As there were only a few studies, there is a need to further investigate the presence of active chemicals and other emerging contaminants in the Zambian environment.
Table 5. Occurrences of ACs in the Zambian environmental matrices.
Matrix Substance Concentration References
Urine Sulfamethoxazole 7740 µg/L [45]
Trimethoprim 12,800 µg/L
Lamivudine 10,010 µg/L
Surface water Antibiotics 11,800 ng/L
Antivirals 49,700 ng/L
Effluents Antibiotics 100–300,400 ng/L
Antivirals 680–55,760 ng/L

This entry is adapted from 10.3390/app12010056


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    Ripanda, A.S. A Focus on Active Chemicals in Sub-Saharan Africa. Encyclopedia. Available online: (accessed on 23 May 2022).
    Ripanda AS. A Focus on Active Chemicals in Sub-Saharan Africa. Encyclopedia. Available at: Accessed May 23, 2022.
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    Ripanda, A.S. (2021, December 30). A Focus on Active Chemicals in Sub-Saharan Africa. In Encyclopedia.
    Ripanda, Asha Shabani. ''A Focus on Active Chemicals in Sub-Saharan Africa.'' Encyclopedia. Web. 30 December, 2021.