Active ingredients in pesticides will only give play to their roles after being contacted, taken or absorbed by pests or protected objects. Most technical materials in pesticides cannot be sprayed with water, or evenly dispersed on protected crops or control targets or in working areas by other means due to their poor water solubility, hence they must be made into various formulations for use through formulation processing. Different auxiliary materials used in pesticide formulation processing other than active ingredients are collectively referred to as adjuvants. Proportions of pesticide adjuvants in pesticide formulations account from a few percentages to over ninety percent, which don’t have activity of pesticides and functions of active ingredients themselves, but can or could benefit improvement and enhancement of pesticide products’ physical and chemical properties.
Pesticide adjuvants play an important role in preparing pesticide formulations and giving active ingredients optimal efficacy. However due to potential hazards of pesticide adjuvants to eco-environment and human health, different countries throughout the world have been paying increasing attention to administration of adjuvant ingredients in pesticide formulations, and they focus more on the safety of their uses now instead of their functions in pesticide formulation processing. CIRS has summarized different countries’ pesticide adjuvant administration, and mainly introduced current status, existing issues and future regulatory trend of China’s pesticide adjuvant administration to allow related enterprises to have a better understanding of adjuvant related policies and regulatory requirements.
1. Classification of pesticide adjuvants
Despite various types of pesticide adjuvants, there’s no unified international nomenclature and classification yet. Adjuvants can be divided into the following four types by their functions:
Table 1 Functions and types of pesticide adjuvants
Disperse and dilute active ingredients
Dispersants, emulsifiers, solvents, diluents, fillers and carriers
Benefit targets’ contact and absorption of pesticides
Wetting agents, penetrants and spreaders
Enable the pesticides to take effect, and to prolong and enhance their efficacy
Stabilizing agents, release control adjuvants and synergists
Increase safety and facilitate application
Drift control agents, pesticide hazard mitigation agents, antifoaming agents and foaming agents
Pesticide adjuvants can be divided into processing adjuvants and tank-mix adjuvants (or spray adjuvants) by their uses. The formers are mainly used in pesticide processing, which facilitate solid and liquid technical materials’ dispersion in spray carriers (water) in an even and stable manner, such as emulsifiers, wetting agents and dispersants. The latters are pesticide adjuvants added into pesticide barrels (or sprayers) before spraying, which are different in types and dosages.
China used to divide pesticide adjuvants into two major classes of surfactants (including natural and synthetic ones) and nonsurfactants by classification methods of surfactants. Commonly seen surfactant pesticide adjuvants include dispersants, emulsifiers, wetting agents, penetrants, spreaders, foaming agents, antifoaming agents, stabilizers and anticoagulants. Non surfactant pesticide adjuvants include: diluents, solvents, co-solvents, carriers, fillers antistatic agents, anticaking agents, phytotoxicity relievers, antifreeze agents, pH regulators, propellants and synergists.
2. Overview of pesticide adjuvant administration in different countries throughout the world
EU has relatively complete theories and legislation system for administration of pesticide adjuvants, which are mainly subject to administration of Pesticide Regulation 1107/2009 as well as REACH Regulation (EC) 1907/2006. Through implementation of REACH system, pesticide adjuvant administration has divided unacceptable adjuvants into 3 classes: adjuvants of high concern (don’t need risk assessment), adjuvants of concern (require risk assessment) and other adjuvants (require risk assessment). Although there’s no unified list of unacceptable adjuvants applicable to EU at the moment, Spain, Germany and some other countries have their own lists of unacceptable adjuvants, and Spain has also provided related limits of impurities for adjuvants with related impurities, such as limited toluene contents in petroleum derivatives of no more than 3% as well as explicit provisions on length of carcinogenic fibers in adjuvants.
2.2 United States
US took the lead in implementation of pesticide adjuvant administration in the world, and the EPA carried out classified (divided into 4 classes in total) administration of adjuvants based on toxicities and exposure hazards of different compounds at the beginning of 1980s. Among which, Class I adjuvants were those proved hazardous to human health and environment, which included 42 compounds; Class II adjuvants were substances similar to Class I adjuvants in structure but have potential or documented toxicities, which included 65 compounds; Class III adjuvants were compounds with unknown toxicities, which included approx. 1,100 compounds; while Class IV adjuvants were those with minor toxicity or almost nontoxic, which were further divided into Class IV.A and Class IV.B. EPA has been continuously updating contents of the list based on progress, and applicants may provide corresponding registration data based on the requirements of the classes of adjuvants used. US implemented Food Quality Protection Act in 2007, and the EPA divided pesticide adjuvants into the followings based on reassessment: the two classes of food (included two classes of adjuvants used before and after crop harvesting and adjuvants only used before crop harvesting) and non-food crop (included essence) adjuvants, and prescribed requirements on limits, scope of application, method of application and quality of certain adjuvants respectively. In 2014, EPA announced removal of 72 adjuvants from list of 371 ingredients (positive list) proposed by applicants, and manufacturers are only allowed to use those compounds after providing related research information that prove their safety and passing EPA’s assessment. It can be seen from the list of the 72 substances, EPA has strengthened adjuvant administration, particularly the control over EDCs, POPs, carcinogens, highly toxic/extremely toxic/hazardous chemicals, environmentally and ecologically hazardous substances, hazardous with corrosivity/ irritation /permeability/strong oxidizing property/silicosis possibility and bioactive substances.
Health Canada Pest Management Regulatory Agency (PMRA) formulated and administrative regulation on pesticide adjuvants in 2004, which’s implemented as of January 9, 2005. There are over 1,200 compounds that can be used or previously used as pesticide adjuvants in Canada, and most of them are divided into five major classes of 1, 2, 3, 4A and 4B by descending order of toxicity, hazardness and administrative intensity based on USEPA’s classification method. In addition, there are also two classes of special adjuvants used in Canada and adjuvants prescribed in Montreal Convention. Canada’s adjuvant administration policies apply to adjuvants used in pesticide processing and tank-mix adjuvants. The purpose is to increase consistency between Canada’s adjuvant administration and USEPA’s adjuvant administration through adoption and building of its own adjuvant list.
3. History and current status of China’s pesticide adjuvant administration
China has been mainly focusing on administration of active ingredients of pesticides instead of carrying out systematic administration of adjuvants since its implementation of administration of pesticide registration, and safety research and administration of adjuvants are still at early stage at the moment:
- Pesticide Professional Committee of CIESC held ‘Academic Seminar on Development Strategy of Pesticide Adjuvants During China’s 11th Five-Year Plan’ between December 22nd and 24th, 2000, which’s both the first professional meeting of China’s pesticide circles in the 21st century and the first themed seminar on adjuvant related issues organized by domestic pesticide circles for many years. Topics of this seminar focused on development direction of China’s pesticides and pesticide adjuvants as well as exploration of drawbacks of China’s pesticide adjuvant industry and countermeasures.
- In September 2005, mosquito coils of 11 brands distributed from the mainland to Hong Kong were seized by AFCD and ordered to be taken back by enterprises for unregistered octachlorodipropyl ether content, which received great attention from related domestic authorities. To further protect safety of agricultural products and human and livestock health, and to increase competitiveness of China’s agricultural products and pesticide products in international market, the MOA held a seminar on administration of pesticide adjuvants in Beijing on June 28, 2006. The MOA released Announcement on Strengthening of Administration of Pesticide Products Containing Octachlorodipropyl Ether in November of the same year.
- Sino-US Seminar on Pesticide Adjuvant Administration, which aimed to further improve awareness of pesticide adjuvant administration and learn experiences and practices of US’s pesticide adjuvant administration through Sino-US exchanges, was held in Beijing between April 29 and 30, 2009. Work seminar on application and administration of pesticide adjuvants was held on August 26, 2009, which decided to limit the application of 5 types of organic solvents with prominent hazards (benzene, toluene, xylene, N, N-Dimethylformamide and methanol).
- The chemical industry standard of HG/T 4576—2013 Limits of Harmful Solvents in Pesticide Emulsifiable Concentrates was promulgated for implementation in March 3, 2014, which set limits on harmful solvents in emulsifiable concentrate products: among which mass fractions of benzene, toluene and naphthalene shall be ≤1.0%, mass fractions of ethylbenzene and N, N-Dimethylformamide shall be ≤2.0%, mass fraction of methanol shall be ≤5.0% and the mass fraction of xylene shall be ≤10.0%.
- ICAMA drafted and promulgated List of Banned and Limited Pesticide Adjuvants (Exposure Draft) in July 2015, which included ethylene glycol monomethyl ether, nonyl phenol and 7 other banned adjuvants as well as benzene, methanol and 73 other limited adjuvants. It’s worth mentioning that the exposure draft has been released for almost 4 years, but the formal version has not been issued yet.
- NY/T 2989-2016 Guidelines on Development of Product Specifications for Pesticide Registration promulgated for implementation in April 1, 2017 explicitly pointed out that name, content and other information of propellents shall be submitted in case of aerosol dispenser products, and it’s not allowed to use CFCs as propellents.
- The new Regulation on Pesticide Administration was promulgated for implementation in 2017, and the MOA released Measures on Administration of Pesticide Registration and Data Requirements on Pesticide Registration successively afterwards. New regulations have prescribed certain specific requirements on adjuvant administration, according to provisions of Article 9 of Measures on Administration of Pesticide Registration: the MOA shall publish and adjust the list and limits of banned and limited adjuvants based on toxicity and hazardness of pesticide adjuvants at appropriate time. Where designated adjuvants need to be added in the use, corresponding test data shall be submitted during application for pesticide registration. According to provisions of Article 28: in case of changes in components other than active ingredients of pesticides, holder of pesticide registration certificate shall apply for changes with MOA.
According to provisions of General Provision 1.3 of Data Requirements on Pesticide Registration: in case of pesticide products with designated adjuvants added during the use due to safety, stability and other reasons, data of tests completed for registration of pesticide samples with such adjuvants added shall be submitted. Chemical data in various product registration data have comparatively specific adjuvant related requirements, such as requirement on provision of identifying information of safener, stabilizer, synergist and other limited components, which include common name, ISO name, chemical name, CAS number, CIPAC code, molecular formula and structural formula. Besides, in terms of products with aforesaid limited components, test method and method validation of limited components shall be provided, and their content and permissible variation range shall be identified. Chemical name, CAS number, molecular formula, structural formula, content, function and other information of all adjuvants shall be provided in chemical data of formulation products as well. In respect of safener, stabilizer, synergist and some other adjuvants with special functions, quality specifications, basic physical and chemical properties, sources, safety (such as MSDS), applications at home and abroad and other information shall be provided as well.
- The new version of Data Requirements on Pesticide Registration has related provisions on essence in public health pesticides. Essence belongs to limited adjuvants, which shall be added appropriately with content of no more than 1%. It’s not necessary to apply for change of registration in case of changes in types of essences, in other words, it’s not necessary to submit composition information or apply for change of registration if change in scent of public health pesticide doesn’t lead to obvious change in composition of formulation (change ≤1%).
Overall speaking, China’s pesticide competent authorities have realized the hazards of adjuvants along with necessity of adjuvant safety administration, and promulgated and implemented some regulatory measures on pesticide adjuvants, which played certain positive roles in adjuvant management. It’s mainly reflected by significant reduction in adjuvants used for pesticide emulsifiable concentrates and the dramatic increase in adjuvants used for water-based formulations. Pesticide adjuvants are moving towards the direction of high efficiency, low dosage, low toxicity, easy degradation, environmental safety. However, there’s still a huge gap compared with international pesticide industry’s adjuvant administration. For instance, there’s no specific department and industry organization or special rules and regulations for adjuvant administration, no explicit classification or limits of adjuvants, no adjuvant test method and assessment criteria, and no guideline on proper use of adjuvants, which all need consultation and solution.
4. Regulatory trend of China’s pesticide adjuvants
Market valuation of global pesticide adjuvant market is USD 2.98 billion in 2016, which’s expected to reach USD 4.21 billion by 2022 at CAGR of 5.9%. Therefore, supervision of pesticide market and adjuvant market in particular must be strengthened and made in line with international standards to improve quality of pesticide products, and ensure agricultural produce and food safety.
Since China doesn’t have sound adjuvant administration regulation at the moment, it’s very likely to build adjuvant list administration system for classified administration of adjuvants in the future by borrowing and referring to practices of other countries and regions. Safety assessment on new adjuvants will mainly focus on their potential carcinogenicity, adverse reproductive effects, developmental toxicity, genetic toxicity, endocrine disruption, POPs, bioaccumulation and other impacts. Besides, harmful substances in the pesticide industry as well as substances with bioactivity and used as adjuvants will be placed under rigorous control and administration.