key: cord-0819722-z2hr6fyn authors: Horak, Ilzé; Horn, Suranie; Pieters, Rialet title: Agrochemicals in freshwater systems and their potential as endocrine disrupting chemicals: A South African context() date: 2020-09-24 journal: Environ Pollut DOI: 10.1016/j.envpol.2020.115718 sha: b00d6e7b245b6886c5a975d45e7367561d30ebdb doc_id: 819722 cord_uid: z2hr6fyn South Africa is the largest agrochemical user in sub-Saharan Africa, with over 3 000 registered pesticide products. Although they reduce crop losses, these chemicals reach non-target aquatic environments via leaching, spray drift or run-off. In this review, attention is paid to legacy and current-use pesticides reported in literature for the freshwater environment of South Africa and to the extent these are linked to endocrine disruption. Although banned, residues of many legacy organochlorine pesticides (endosulfan and dichlorodiphenyltrichloroethane (DDT)) are still detected in South African watercourses and wildlife. Several current-use pesticides (triazine herbicides, glyphosate-based herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) and chlorpyrifos) have also been reported. Agrochemicals can interfere with normal hormone function of non-target organism leading to various endocrine disrupting (ED) effects: intersex, reduced spermatogenesis, asymmetric urogenital papillae, testicular lesions and infertile eggs. Although studies investigating the occurrence of agrochemicals and/or ED effects in freshwater aquatic environments in South Africa have increased, few studies determined both the levels of agricultural pesticides present and associated ED effects. The majority of studies conducted are either laboratory-based employing in vitro or in vivo bioassays to determine ED effects of agrochemicals or studies that investigate environmental concentrations of pesticides. However, a combined approach of bioassays and chemical screening will provide a more comprehensive overview of agrochemical pollution of water systems in South Africa and the risks associated with long-term chronic exposure. South Africa's semi-arid climate makes it ideal for the cultivation of various crops (Quinn et 314 al., 2011; Yahaya et al., 2017) , including maize, soybean, sunflower, wheat, sugar cane and 315 a variety of citrus fruits. Approximately 15 million hectares of South Africa's land is used for 316 cultivation, accounting for 12 to 13% of the country's total area of 122 million hectares (Van 317 der Laan et al., 2017). South Africa has an estimated poverty rate of 28%, which is 318 equivalent to more than 16 million individuals living in extreme poverty (World Poverty Clock, 319 2020). As a result, the country's emerging economy is highly dependent on agriculture in 320 terms of job creation and poverty alleviation (Olujimi et al., 2010) . However, crop production 321 in South Africa is not considered sustainable because it comes at an ecological cost due to 322 the vast amount of agrochemicals applied (Van der Laan et al., 2017; Yahaya et al., 2017) . 323 In the 1970s, Africa's pesticide load significantly increased when large quantities of dichloro-324 diphenyltrichloroethane (DDT), malathion and many other pesticides were "donated" to 325 African countries for malaria vector control, following their ban in developed countries 326 (Osibanjo et al., 2002; Manyilizu, 2019) . Apart from disease vector control, the strive for food 327 hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), mirex, and toxaphene) (Taiwo, 497 2019). These pesticides are highly lipophilic, not easily degraded by microorganisms and 498 characterised by long half-lives (from 60 days up to 15 years) due to their high accumulation 499 and slow degradation potential (Schlenk et (predominantly DDT) have been well-documented in wildlife across South Africa (Table 1) . 502 503 Fish and other aquatic species are especially vulnerable since they are directly exposed to 504 OCPs through water and their diets, allowing for the concentration of pesticides in their 505 tissue (Taiwo, 2019). Barnhoorn et al. (2015) evaluated the presence of OCPs in C. 506 gariepinus inhabiting three severely polluted impoundments, the Roodeplaat-, Rietvlei-and 507 Hartbeespoort reservoirs (Table 1) . Across all three sampling sites, 52 of the 60 fish 508 The country is known for its rich biodiversity, containing 7% of the world's bird, mammal and 523 reptile species; 8% of its plant species and 15% of its coastal marine species (Cherry, 2005) . 524 The country is also home to ten World Heritage Sites, including the iSimangaliso Wetland 525 Park on the East Coast of South Africa (Table 1) The presence of OCPs in marine and freshwater biota is of concern. Fish play an important 552 role in different trophic levels, as well as in the cycling of essential nutrients in aquatic 553 environments (Islam et al., 2018). Sharks and crocodiles are both important apex predators 554 within their respective food webs. They fulfil important ecological roles such as limiting prey 555 populations and preventing bottom-up driven ecosystems (Wallach et al., 2015) . Coral reefs 556 are productive ecosystems that form nurseries for a wide variety of fish species and prevent 557 coastal erosion (World Wildlife Fund, 2020), while mussels are an important part of the 558 South African aquaculture industry, accounting for 1 140 tonnes or 37.4% of the total 559 mariculture production in 2013 (Department of Agriculture, Forestry and Fisheries, 2017). 560 Moreover, the presence of OCPs in ecologically important regions in South Africa is 561 worrisome as many of these areas are not surrounded by intense agricultural or domestic 562 activities. In many cases, the fish species from these areas serve as a food source for local 563 people from the surrounding villages. The OCPs therefore not only pose a threat to wildlife 564 and biodiversity but also the health of local communities. (Table 1) . Atrazine (2-chloro-4-ethylamino-6-isopropyl-amino-s-triazine) is probably the 572 best-known herbicide in the triazine class and is widely used in both pre-and early post- indicating herbicide movement to non-target areas as was also observed by Curchod et al. 594 (2020) ( Table 1) . The presence of pesticides in the surface water of three rivers in the 595 Western Cape was compared with spray records, with the majority of pesticides detected, 596 but not listed, being herbicides such as atrazine, simazine, terbutryn, prometryn and (Table 1) . Since the geohydrological data 599 showed no evidence of interaction between the surface-and groundwater, the study 600 concluded that groundwater is being polluted by an unknown source. Recently, Barnhoorn 601 and Van Dyk (2020) ( Table 1) were the first to report on the presence of certain triazine 602 herbicides (including simazine, atrazine and terbuthylazine) in the freshwater impoundment 603 of the Roodeplaat Dam. This water source supports several agricultural and residential 604 activities that are most likely responsible for the pesticide contamination. (Table 1) . 807 808 Although ED effects have been investigated in South African freshwater, few studies follow a 809 combined approach of investigating both agrochemicals and ED effects. This is of concern 810 as the ED effects of many current-use pesticides in South Africa are unknown. This was 811 evidenced by Dabrowski et al. (2014) . As part of an agricultural pesticide prioritisation study, 812 an initial screening process yielded 152 active ingredients which are applied to South African 813 crops on a national scale. Around 9% of the active ingredients were known EDCs. Of the 814 remaining 91%, there was no data available for ~57%, only possible evidence for ~22% and 815 Endocrine disrupting effects were evaluated by measuring the response of different male Sprague-Dawley rats. Rats exposed to DDT and DDE exhibited a higher prostate and 829 testicular mass, respectively. Exposure to a mixture of pesticides resulted in a shorter 830 anogenital distance, compared to the control group. An imbalance in thyroid and vitamin A 831 homeostasis has also been found to be associated with DDT (Delport et al., 2011) . 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