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

TY - JOUR

T1 - Characterization of the Nairobi River catchment impact zone and occurrence of pharmaceuticals

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

N1 - Funding Information: This study was supported by AstraZeneca UK, Global Safety, Health and environment, Macclesfield, UK and the Biogeochemistry Research Centre, School of Geography, Earth and Environmental Sciences, University of Plymouth, PL4 8AA, UK. Funding Information: This study was supported by AstraZeneca UK, Global Safety, Health and environment, Macclesfield, UK and the Biogeochemistry Research Centre, School of Geography, Earth and Environmental Sciences, University of Plymouth, PL4 8AA, UK. Appendix A Funding Information: The authors confirm that there are no actual or potential conflict of interest including any financial, personal or other relationships with other people or organizations within three years of beginning the submitted work that could inappropriately influence, or be perceived to influence, their work. This study was supported by AstraZeneca UK, Global Safety, Health and environment, Macclesfield, UK and the Biogeochemistry Research Centre, School of Geography, Earth and Environmental Sciences, University of Plymouth, PL4 8AA, UK. Publisher Copyright: © 2019 Elsevier B.V.

PY - 2020/2/10

Y1 - 2020/2/10

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.

AB - 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.

KW - Kenya

KW - Nairobi

KW - Pharmaceuticals

KW - Risk assessment

KW - Wastewater

KW - Water quality

UR - http://www.scopus.com/inward/record.url?scp=85074767510&partnerID=8YFLogxK

U2 - 10.1016/j.scitotenv.2019.134925

DO - 10.1016/j.scitotenv.2019.134925

M3 - Article

C2 - 31726303

SN - 0048-9697

VL - 703

JO - Science of the Total Environment

JF - Science of the Total Environment

M1 - 134925

ER -