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Prevalence of Eight Phthalate Monoesters in Water from the Okavango Delta, Northern Botswana


Phthalate diesters are used in personal care products, plastics, and pesticides, resulting in widespread human and wildlife exposure. Phthalate diesters leach out of these products and ultimately enter biological systems where they are quickly metabolized to phthalate monoesters and glucuronides. As such, phthalate monoesters can serve as indicators of anthropogenic activity in wilderness areas. The Okavango Delta, an inland seasonal wetland covering 5000–12,000 km2 in Botswana, provides fresh water to many species of birds, fish, reptiles, and large mammals. Water samples (N = 46) were taken from across the Okavango water system, extracted, and analyzed for eight different phthalate monoesters using liquid chromatography and isotope dilution mass spectrometry. Seven of eight phthalate monoesters were detected from the low ng/L to low µg/L levels. Phthalate monoesters were found in samples from all five sampling regions. Sources of these contaminants are unknown, but their presence indicates encroachment of human activity on the Okavango Delta.

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We greatly appreciate the hospitality, guidance, and field assistance of Ineelo Mosie, Rele Sekotswe, Guy Lobjoit, Brandon Moore, Mike Murray-Hudson, Keta Mosepele and the Okavango Research Institute. Also support came from other members of the Brock research group, Emily Phillips and Michael Way; the Coypu Foundation; and the University of North Carolina Asheville.


This study was funded primarily by the University of North Carolina Asheville with additional support from the Fulbright Foundation, Coypu Foundation and the Okavango Research Institute.

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Correspondence to John W. Brock.

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Bartsch, P.W., Edwards, T.M. & Brock, J.W. Prevalence of Eight Phthalate Monoesters in Water from the Okavango Delta, Northern Botswana. Bull Environ Contam Toxicol 103, 274–279 (2019).

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  • Phthalates
  • Okavango Delta
  • Water
  • River