Part III POPs-free/POPs alternatives – overview and case studies
Alternatives to Endosulfan
Alternatives to Endosulfan
By its decision SC-5/3, the Conference of the Parties to the Stockholm Convention on Persistent Organic Pollutants (COP) decided to amend part I of Annex A to the Convention to list therein technical endosulfan and its related isomers, with specific exemptions. Therefore alternatives to a wide range of applications were needed.
Chemical and non-chemical alternatives to endosulfan are available in many geographical situations both in developed and developing countries. Some of these alternatives are being applied in countries where endosulfan has been banned or is being phased-out. However, in some countries, it may be difficult and/or costly to replace endosulfan for specific crop-pest complexes.
The Persistent Organic Pollutants Review Committee (POPRC), at its seventh meeting, was requested to assess the alternatives to endosulfan in accordance with the general guidance on considerations related to alternatives and substitutes to listed persistent organic pollutants and candidate chemicals. It subsequently provided to the 6th Conference of the Parties (COP) two documents, one on non-chemical alternatives and one on chemical alternatives to endosulfan. The POPRC recommended, and the COP agreed, to give priority to ecosystem approaches (essentially non-chemical) to pest control when replacing endosulfan.
The report lists in Annex II 110 chemical alternatives for the different exempted application areas.
The report provided hazard-based information on the alternatives with respect to the POP criteria in Annex D of the Stockholm Convention and other relevant hazard criteria.
For the 1st screening the POPRC developed following categorization with data analysis:
a)Category 1: High potential to be persistent organic pollutants ‐ BCF >5000, persistence:DT50 for whole water-sediment system >60 days
b)Category 2: Candidates that could be POPs substances – BCF >1000, persistence: DT50 soil or whole water-sediment system >60 days and/or a PB‐score >1 (P‐score >0.5)
c)Category 3: Candidates that are difficult for prioritization; log Kow >3.5 (in absence of an experimental BCF value), DT50 soil or whole water-sediment system >60 days and/or a PB-score >1 (P-score >0.5).
d)Category 4: Unlikely to be persistent organic pollutants; BCF <1000 or log Kow <3.5), DT50 water-sediment or soil<60 days
According to the report, out of the 110 chemical alternatives 84 are unlikely to be a POP on basis of screening against the criteria described above. Two substances were deemed to be potential POP candidates, whereas 18 were classed as candidates for further assessment and 6 as candidates for further assessment with limited data. The category IV substances were not further analysed. Substances in category I, II and III were further assessed, results of which presented in section IV and Annex IV of the report.
The report stated that no monitoring data or other evidence as provided for in Annex D of the Convention had been analysed. Furthermore, the report mentioned that the substances deselected for further assessment (category IV) may exhibit other characteristics that should be considered in the authorization of the substance as an insecticide by Parties, such as carcinogenicity or neurotoxicity (cf. section 4). The prioritization should be seen as only a screening analysis of persistence (P) and bioaccumulation (B) properties of the alternatives.
It is important to note that the assessment is not a comprehensive and an in depth assessment of all available information as only a limited number of databases have been consulted and degradation products were not covered.
The screening also only focuses on POP characteristics. The report strongly recommends that further assessment needs to be carried out within the national frameworks of authorization. In addition, substances which have been identified in the report as not likely to be a POP, may still exhibit hazardous characteristics that should be assessed by Parties before considering such substances as a suitable alternative. Therefore national authorities should be aware of other hazardous characteristics when authorizing these substances.
Some examples of chemical alternatives:
•malathion (used in the Sahel region against the cotton bollworm on cotton);
•cyromazin (used in Canada against the Colorado potato beetle (Leptinotarsa decemlineata) on potato);
•bifenthrin (used in China against white fly on tea).
The document evaluates the non-chemical alternatives in two parts: the first-part is an evaluation of ecosystem approaches to management of pests in the listed crop/pest complexes, and the second part is an evaluation of non-chemical alternatives that are used within the existing chemical input-based agricultural approach as simple substitutes for endosulfan.
The ecosystem approach to pest management is now the internationally preferred option, as in FAO’s calls their ecosystem approach ‘sustainable crop production intensification, in which emphasis is placed on improving soil health, conserving natural enemies of pests, a preventative approach, and cultural and management techniques, with pesticides used as a last resort.
Ecosystem approaches, or agroecology, includes organic agriculture and some traditional, and improved traditional, approaches such as Community Managed Sustainable Agriculture. Such approaches have shown increased or similar yields, greater returns to farmers, and improvement in social and environmental indicators.
The focus is on managing the agro-ecosystem to avoid build-up of pests, using wherever possible cultural, biological, and mechanical methods instead of synthetic materials.
Practices include using resistant varieties better adapted to ecologically based production than those bred for high-input agriculture, crop diversity, crop rotation, intercropping, optimized planting time and weed management, conserving natural enemies, and managing crop nutrient levels to reduce insect reproduction.
It is difficult to provide a prescription for a particular crop/pest complex in these systems as the entire interwoven management process is crucial to protecting crops from pests. Each crop/pest complex needs to be looked at within the specific agroecosystem, taking into account many aspects, including climatic and geographical variables, presence of natural enemies and availability of biological controls, the structure and function of the particular farm, and microclimatic variations within it.
The report also concluded that there is a large range of discrete non-chemical options that can be used in ecosystem, IPM, or in chemical-input based agriculture as simple substitutes. These include natural plant extracts, attractant lures and traps, and biological controls such as pathogens, predators, and parasitoids. The availability and technical feasibility of these may differ between countries.
Selected examples of non-chemical alternatives:
•Bacillus thuringiensis (bacterium used in Canada against the diamondback moth on cauliflower);
•Metarhizium flavoviride (fungus used in West Africa against locusts on rice and wheat);
•Phymastichus coffea (wasp used in Mexico and Costa Rica against the coffee berry borer on coffee).
In 2008, PAN Germany have developed a field guide to non-chemical pest management in banana, cabbage and other crucifers, cassava, citrus, coffee, corn, cotton and other fiber crops, cowpea, eggplant, forage crops, forest trees, garlic, lettuce, mango, mungbean, onion, ornamentals, peanut, pepper, pigeon pea, oil crops, ornamentals, potato, rice, sesame, sorghum, soybean, squash and other cucurbits, string bean, sweet potato, tea, tomato, and wheat production, namely “How to Grow Crops without Endosulfan”. The content of this publication is based on the information provided at www.oisat.org. It enables to provide farmers with practical guides to avoid the use of Endosulfan. The recommended practices are scientifically based. Most of the farm practices described in this publication, the farmers can do by themselves.
Also IPEN have published the booklet “Alternatives to Endosulfan in Latin America” that illustrates the variety of alternatives to endosulfan beyond the chemical substitution approach that means go beyond chemical pesticides that are less toxic and less persistent, but also agroecological and organic agricultural practices used in growing soybeans, coffee, vegetables, flowers and tobacco in Latin American countries.
Project/Case study Endosulfan substitution in Uganda and Mozambique
A guidance to assist countries to undertake an assessment of continued need of endosulfan and of potential alternative chemical and non-chemical option has been developed and is available in the Stockholm Convention website. The guidance includes tools and information gathered by POPRC and other scientific bodies and allows countries to determine main crops and related pests where endosulfan is used at national level, but most importantly it provides a method towards its sustainable substitution. Currently a project on substitution of endosulfan is conducted in Uganda and Mozambique.