The use of a simple model for the regulatory environmental risk assessment of pesticides in Ethiopia.

Pesticide registration in developing countries like Ethiopia is often not supported by substantiated risk assessment procedures. In this study, we evaluated the PRIMET (Pesticide Risks in the Tropics for Man, Environment and Trade) Registration_Ethiopia_1.1 model which is a tool developed to assess the risks to non-target protection goals. All the 103 registered active ingredients (a.i.) in Ethiopia, except those used for flower and storage pest control purposes, were evaluated on their environmental risks. Data on physico-chemical characteristics, toxicity and pesticide use patterns were mined from either the information given in the dossier or public databases. Together with scenarios specifically developed for Ethiopia, these data were used to perform a risk assessment for the aquatic and terrestrial environment as well as for vertebrates including humans via contaminated drinking water exposure. Results indicated that 11 and 16% of the a.i.s are indicated to pose high acute risk and 7.3 and 11% high chronic risks for fish and aquatic invertebrates, respectively. Similarly, 5.5 and 8.7% high acute risks and 6.8 and 3.9% high chronic risks were observed for the soil ecosystem and birds, respectively. 23% of the evaluated active ingredients were indicated to be highly risky to bees when beehives are present inside the sprayed crop while 7.8% of them are highly risky when beehives are present outside the field of the sprayed crop. The fungicide metalaxyl, the herbicides acetochlor, alachlor, mecoprop and tembotrion, and the insecticides carbaryl, chlorpyrifos, diazinon and methidathion were predicted to pose high acute or chronic risks to humans or other vertebrates if surface water is used as a source of drinking water. Future studies should give emphasis on how the risk assessment results of this study can be implemented to aid the registration process.

Interventions to Reduce Pesticide Exposure from the Agricultural Sector in Africa: A Workshop Report.

Despite the fact that several cases of unsafe pesticide use among farmers in different parts of Africa have been documented, there is limited evidence regarding which specific interventions are effective in reducing pesticide exposure and associated risks to human health and ecology. The overall goal of the African Pesticide Intervention Project (APsent) study is to better understand ongoing research and public health activities related to interventions in Africa through the implementation of suitable target-specific situations or use contexts. A systematic review of the scientific literature on pesticide intervention studies with a focus on Africa was conducted. This was followed by a qualitative survey among stakeholders involved in pesticide research or management in the African region to learn about barriers to and promoters of successful interventions. The project was concluded with an international workshop in November 2021, where a broad range of topics relevant to occupational and environmental health risks were discussed such as acute poisoning, street pesticides, switching to alternatives, or disposal of empty pesticide containers. Key areas of improvement identified were training on pesticide usage techniques, research on the effectiveness of interventions targeted at exposure reduction and/or behavioral changes, awareness raising, implementation of adequate policies, and enforcement of regulations and processes.

Impacts of nutrients and pesticides from small- and large-scale agriculture on the water quality of Lake Ziway, Ethiopia.

The area around Lake Ziway in Ethiopia is going through a major agricultural transformation with both small-scale farmers and large horticultural companies using pesticides and fertilisers at an increased rate. To be able to understand how this influences the water quality of Lake Ziway, water quality data was gathered to study the dynamics of pesticide concentrations and physicochemical parameters for the years from 2009 to 2015. Results indicate that for some physicochemical parameters, including pH, potassium and iron, over 50 % of the values were above the maximum permissible limit of the Ethiopian standard for drinking water. The fungicide spiroxamine poses a high chronic risk when the water is used for drinking water, while the estimated intake of diazinon was approximately 50 % of the acceptable daily intake. Higher-tier risk assessment indicated that the fungicide spiroxamine poses a high acute risk to aquatic organisms, while possible acute risks were indicated for the insecticides deltamethrin and endosulfan. Longer-term monitoring needs to be established to show the water quality changes across time and space, and the current study can be used as a baseline measurement for further research in the area as well as an example for other surface water systems in Ethiopia and Africa.

Monitoring and risk assessment of pesticides in irrigation systems in Debra Zeit, Ethiopia.

Since Ethiopia is going through a rapid transformation of its agricultural sector, we assessed the human health and environmental risks due to the past use of organochlorine pesticides (OCPs) as well as the risks of the current pesticide use by farmers. A monitoring programme and risk assessment was carried out for the Wedecha-Belbela irrigation system in the Debra Zeit area. The Wedecha and Belbela rivers and adjacent temporary ponds were sampled and examined for the presence of OCPs between August and October 2014, while data on the current pesticide use by small- and large-scale farmers was collected by interviews. The usage patterns were evaluated for risks of using the river or temporary ponds as source of drinking water and for risks for the aquatic ecosystems in the river and ponds with the aid of the PRIMET_Registration_Ethiopa_1.1 model. The samples were collected in five sampling periods, and results indicate that most of the 18 target OCPs were not detected above the detection limit, while g-chlordane may pose chronic risks when surface water is used as drinking water. Endosulfan and heptachlor pose risks to aquatic organisms at second-tier level, while for heptachlor-epoxide B, g-chlordane and b-BHC only risks could be determined at the first tier due to a lack of data. For all nine pesticides used by small-scale farmers the calculated acute risks to humans were low. Second tier risk assessment for the aquatic ecosystem indicated that lambda-cyhalothrin, endosulfan, profenofos, and diazinon may pose high risks.

Sensitivity of Ethiopian aquatic macroinvertebrates to the pesticides endosulfan and diazinon, compared to literature data.

The aims of the present study were to present a methodology for toxicity tests that can be used when analytical resources to verify the test concentrations are limited, and to evaluate whether the sensitivity of a limited number of Ethiopian species to pesticides differs from literature values for, mainly, temperate species. Acute toxicity tests were performed using three Ethiopian aquatic invertebrate species, one crustacean (Diaphanosoma brachyurum) and two insects (Anopheles pharoensis and Culex pipiens) and using the pesticides endosulfan and diazinon. All species-pesticide combinations were tested in duplicate to estimate the consistency, i.e. the intra-laboratory variation, in test results. Daphnia magna was tested as well to allow the test results to be compared directly with values from the literature. Results indicate that the differences between the EC50s obtained for D. magna in this study and those reported in the literature were less than a factor of 2. This indicates that the methodology used is able to provide credible toxicity values. The results of the duplicated tests showed intra-laboratory variation in EC50 values of up to a factor of 3, with one test showing a difference of a factor of 6 at 48 h. Comparison with available literature results for arthropod species using species sensitivity distributions indicated that the test results obtained in this study fit well in the log-normal distribution of the literature values. We conclude that the methodology of performing multiple tests to check for consistency of test results and performing tests with D. magna for comparison with literature values to check for accuracy is able to provide reliable effect threshold levels and that the tested Ethiopian species did not differ in sensitivity from the arthropod species reported on in the literature.

Surface water risk assessment of pesticides in Ethiopia.

Scenarios for future use in the pesticide registration procedure in Ethiopia were designed for 3 separate Ethiopian locations, which are aimed to be protective for the whole of Ethiopia. The scenarios estimate concentrations in surface water resulting from agricultural use of pesticides for a small stream and for two types of small ponds. Seven selected pesticides were selected since they were estimated to bear the highest risk to humans on the basis of volume of use, application rate and acute and chronic human toxicity, assuming exposure as a result of the consumption of surface water. Potential ecotoxicological risks were not considered as a selection criterion at this stage. Estimates of exposure concentrations in surface water were established using modelling software also applied in the EU registration procedure (PRZM and TOXSWA). Input variables included physico-chemical properties, and data such as crop calendars, irrigation schedules, meteorological information and detailed application data which were specifically tailored to the Ethiopian situation. The results indicate that for all the pesticides investigated the acute human risk resulting from the consumption of surface water is low to negligible, whereas agricultural use of chlorothalonil, deltamethrin, endosulfan and malathion in some crops may result in medium to high risk to aquatic species. The predicted environmental concentration estimates are based on procedures similar to procedures used at the EU level and in the USA. Addition of aquatic macrophytes as an ecotoxicological endpoint may constitute a welcome future addition to the risk assessment procedure. Implementation of the methods used for risk characterization constitutes a good step forward in the pesticide registration procedure in Ethiopia.