OECD work on avian toxicity testing required commitment from countries and industry in terms of manpower and laboratory resources to perform experimental testing and generate data.

It was decided by the OECD Working Group of the National Coordinators of the Test Guidelines Programme (WNT) to publish useful information for those who are interested in avian chemical toxicity testing with the view to protect wildlife birds.

A number of avian toxicity studies projects were included in the Test Guidelines Programme over the last twenty years, following an OECD survey conducted in 1993 by the Pesticides Programme. The objective of the survey was to set priorities for the revision and development of Test Guidelines used to generate toxicity data prior to pesticides registration.

The OECD work on birds toxicity testing started in 1994 with a SETAC/OECD Workshop on Avian Toxicity Testing, held in Pensacola, Florida, in December 1994. The report of the workshop was published in 1996 in the series on Testing and Assessment, No. 5. The workshop identified four priority areas on which experts from OECD countries worked collaboratively between 1994 and 2015, as further explained below.

These key points for the design and interpretation of studies on avoidance of pesticides by birds are unresolved, demonstrating that the need for further OECD work on this topic is not warranted.

• The purpose of a consensus document will be to provide help in deciding whether to do an avian avoidance study (for notifiers and regulators) and how to design studies and help risk assessors in evaluating the contribution of available data to an overall weight-of-evidence assessment. It will not be a prescriptive document because studies need to be designed case by case.
• The role of avian avoidance testing in the risk assessment of pesticides: although testing for avoidance by birds is no longer a regulatory requirement for pesticides registration in OECD countries, notifiers often submit avian avoidance studies to the competent authorities.
• Is there a need for guidance on the conduct, use and interpretation of avoidance studies in birds? It is generally recognised that due to the complexity of factors affecting avoidance, interpreting data on avoidance from studies with captive birds, and assessing its implication for risk in the field, is difficult and uncertain.
• Use of avoidance tests: In general avoidance studies are considered as part of a wider package of information. In some cases, avoidance studies may be considered stand-alone information, supported by feeding rates.
• Acute effects vs. chronic effects: explanation of reasons why avian avoidance behaviour data will not address reproduction/ chronic effects.
• Available tests: description of available avoidance tests.
• Delivery: seed types, seed size, treated food types, plants, etc. The mode of delivery should be acceptable to species used in the study. It should be appropriate to the intended crop formulation (seed of interest, coated/uncoated, moisture content, etc.). A matrix/ flowchart might be useful to provide answers.
• Species: species include: (i) ecological relevance; (ii) sensitivity; (iii) feeding rate; and (iv) husking.
• Loading: loading involves (i) relation to field levels including nominal and after decay; and (ii) actual level and potential change during experiment (measured, expected).
• Feeding rate: feeding rate in laboratory involves: (i) presentation of food (amount, spread, in pots, etc.); (ii) preparation of the animals (hunger, feeding time, training); (iii) group size, flocking effects; (iv) body condition relevant for time of year; and (v) prior experience of untreated food of same type.
• Number of choices available: the selection of choice (for food) involves: (i) no choice; (ii) choice in time; and (iii) concurrent choice.
• Endpoints: the endpoints to be measured are: (i) mortality; (ii) sublethal effects, types, severity, how and when recorded; (iii) food consumption (g/day or g/bird for defined periods of time) and feeding rate (peck rate, etc.); (iv) other endpoints e.g. physiological, pathological; and (v) early termination and how to interpret this.
• Statistical issues: the statistics-related issues are: (i) design; (ii) controls (sequential, concurrent, positive control); and (iii) analysis: confidence intervals, significance, validity of assumptions of statistical analysis.
• Regurgitation: is regurgitation recorded, and what are the implications for interpretation and extrapolation of results?
• Confounding factors: confounding factors influencing response can be: (i) vapour pressure (pots, etc.), indoor, ventilation, outdoors; and (ii) other routes of exposure in laboratory or field.
• Test animals: there are a number of elements associated to the test animals: (i) source, wild versus captive, acclimatisation period; (ii) strain and homogeneity of laboratory-bred animals; (iii) age, sex, young birds (more sensitive?), birds metabolically mature; and (iv) health status, infection, etc.
• Test environment: test environment involves: (i) indoors, outdoors; (ii) temperature, other conditions; (iii) quality of testing conditions including precautions for disturbance by observers, experimental/technical activities etc., noise levels and type.