Characterization of the Nairobi River catchment impact zone and occurrence of pharmaceuticals: Implications for an impact zone inclusive environmental risk assessment

Simone Bagnis; Alistair Boxall; Antony Gachanja; Mark Fitzsimons; Martin Murigi; Jason Snape; Alan Tappin; John Wilkinson; Sean Comber

doi:10.1016/j.scitotenv.2019.134925

Characterization of the Nairobi River catchment impact zone and occurrence of pharmaceuticals: Implications for an impact zone inclusive environmental risk assessment

Simone Bagnis, Alistair Boxall, Antony Gachanja, Mark Fitzsimons, Martin Murigi, Jason Snape, Alan Tappin, John Wilkinson, Sean Comber

Environment and Geography

Research output: Contribution to journal › Article › peer-review

Abstract

The largely uncontrolled release of active pharmaceuticals ingredients (APIs) within untreated wastewater discharged to waterbodies, associated with many rapidly urbanising centres is of growing concern owing to potential antimicrobial resistance, endocrine disruption and potential toxicity. A sampling campaign has been undertaken to assess the source, occurrence, magnitude and risk associated with APIs and other chemicals within the Nairobi/Athi river basin, in Kenya, East Africa. The catchment showed an extensive downstream impact zone estimated to extend 75 km, mostly, but not exclusively, derived from the direct discharge of untreated wastewater from the urban centre of Nairobi city. The exact extent of the downstream boundary of the Nairobi city impact zone was unclear owing to the inputs of untreated wastewater sources from the continuous urbanized areas along the river, which counteracted the natural attenuation caused by dilution and degradation. The most frequently detected APIs and chemicals were caffeine, carbamazepine, trimethoprim, nicotine, and sulfamethoxazole. Paracetamol, caffeine, sulfamethoxazole, and trimethoprim alone contributed 86% of the total amount of APIs determined along the Nairobi/Athi catchment. In addition to direct discharge of untreated domestic wastewater attributed to the informal settlements within the conurbation, other sources were linked to the industrial area in Nairobi City where drug formulation is known to occur, the Dandora landfill and veterinary medicines from upstream agriculture. It was shown that there was a possible environmental risk of API ecotoxicological effects beyond the end of the traditional impact zone defined by elevated biochemical oxygen demand concentrations; with metronidazole and sulfamethoxazole exhibiting the highest risk.

Original language	English
Article number	134925
Journal	Science of the Total Environment
Volume	703
Early online date	2 Nov 2019
DOIs	https://doi.org/10.1016/j.scitotenv.2019.134925 https://doi.org/10.1016/j.scitotenv.2019.134925
Publication status	Published - 10 Feb 2020

Bibliographical note

Publisher Copyright:
© 2019 Elsevier B.V.

Keywords

Kenya
Nairobi
Pharmaceuticals
Risk assessment
Wastewater
Water quality

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Cite this

Bagnis, S., Boxall, A., Gachanja, A., Fitzsimons, M., Murigi, M., Snape, J., Tappin, A., Wilkinson, J., & Comber, S. (2020). Characterization of the Nairobi River catchment impact zone and occurrence of pharmaceuticals: Implications for an impact zone inclusive environmental risk assessment. Science of the Total Environment, 703, Article 134925. https://doi.org/10.1016/j.scitotenv.2019.134925, https://doi.org/10.1016/j.scitotenv.2019.134925

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abstract = "The largely uncontrolled release of active pharmaceuticals ingredients (APIs) within untreated wastewater discharged to waterbodies, associated with many rapidly urbanising centres is of growing concern owing to potential antimicrobial resistance, endocrine disruption and potential toxicity. A sampling campaign has been undertaken to assess the source, occurrence, magnitude and risk associated with APIs and other chemicals within the Nairobi/Athi river basin, in Kenya, East Africa. The catchment showed an extensive downstream impact zone estimated to extend 75 km, mostly, but not exclusively, derived from the direct discharge of untreated wastewater from the urban centre of Nairobi city. The exact extent of the downstream boundary of the Nairobi city impact zone was unclear owing to the inputs of untreated wastewater sources from the continuous urbanized areas along the river, which counteracted the natural attenuation caused by dilution and degradation. The most frequently detected APIs and chemicals were caffeine, carbamazepine, trimethoprim, nicotine, and sulfamethoxazole. Paracetamol, caffeine, sulfamethoxazole, and trimethoprim alone contributed 86% of the total amount of APIs determined along the Nairobi/Athi catchment. In addition to direct discharge of untreated domestic wastewater attributed to the informal settlements within the conurbation, other sources were linked to the industrial area in Nairobi City where drug formulation is known to occur, the Dandora landfill and veterinary medicines from upstream agriculture. It was shown that there was a possible environmental risk of API ecotoxicological effects beyond the end of the traditional impact zone defined by elevated biochemical oxygen demand concentrations; with metronidazole and sulfamethoxazole exhibiting the highest risk.",

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Bagnis, S, Boxall, A, Gachanja, A, Fitzsimons, M, Murigi, M, Snape, J, Tappin, A, Wilkinson, J & Comber, S 2020, 'Characterization of the Nairobi River catchment impact zone and occurrence of pharmaceuticals: Implications for an impact zone inclusive environmental risk assessment', Science of the Total Environment, vol. 703, 134925. https://doi.org/10.1016/j.scitotenv.2019.134925, https://doi.org/10.1016/j.scitotenv.2019.134925

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T2 - Implications for an impact zone inclusive environmental risk assessment

AU - Bagnis, Simone

AU - Boxall, Alistair

AU - Gachanja, Antony

AU - Fitzsimons, Mark

AU - Murigi, Martin

AU - Snape, Jason

AU - Tappin, Alan

AU - Wilkinson, John

AU - Comber, Sean

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N2 - The largely uncontrolled release of active pharmaceuticals ingredients (APIs) within untreated wastewater discharged to waterbodies, associated with many rapidly urbanising centres is of growing concern owing to potential antimicrobial resistance, endocrine disruption and potential toxicity. A sampling campaign has been undertaken to assess the source, occurrence, magnitude and risk associated with APIs and other chemicals within the Nairobi/Athi river basin, in Kenya, East Africa. The catchment showed an extensive downstream impact zone estimated to extend 75 km, mostly, but not exclusively, derived from the direct discharge of untreated wastewater from the urban centre of Nairobi city. The exact extent of the downstream boundary of the Nairobi city impact zone was unclear owing to the inputs of untreated wastewater sources from the continuous urbanized areas along the river, which counteracted the natural attenuation caused by dilution and degradation. The most frequently detected APIs and chemicals were caffeine, carbamazepine, trimethoprim, nicotine, and sulfamethoxazole. Paracetamol, caffeine, sulfamethoxazole, and trimethoprim alone contributed 86% of the total amount of APIs determined along the Nairobi/Athi catchment. In addition to direct discharge of untreated domestic wastewater attributed to the informal settlements within the conurbation, other sources were linked to the industrial area in Nairobi City where drug formulation is known to occur, the Dandora landfill and veterinary medicines from upstream agriculture. It was shown that there was a possible environmental risk of API ecotoxicological effects beyond the end of the traditional impact zone defined by elevated biochemical oxygen demand concentrations; with metronidazole and sulfamethoxazole exhibiting the highest risk.

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KW - Pharmaceuticals

KW - Risk assessment

KW - Wastewater

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Bagnis S, Boxall A, Gachanja A, Fitzsimons M, Murigi M, Snape J et al. Characterization of the Nairobi River catchment impact zone and occurrence of pharmaceuticals: Implications for an impact zone inclusive environmental risk assessment. Science of the Total Environment. 2020 Feb 10;703:134925. Epub 2019 Nov 2. doi: 10.1016/j.scitotenv.2019.134925, 10.1016/j.scitotenv.2019.134925

Characterization of the Nairobi River catchment impact zone and occurrence of pharmaceuticals: Implications for an impact zone inclusive environmental risk assessment

Abstract

Bibliographical note

Keywords

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