Methodology used by PAN UK

For nearly two decades, PAN UK has conducted health monitoring surveys using a combination of surveys, desk studies, consultations, group discussion and semi-structured interviews to better understand the issue and triangulate information from different sources. Retrospective, self-reported injury histories collected using survey questionnaires are at the heart of the approach. The questionnaires have been developed by PAN UK and adapted for use in several countries in order to identify common exposure scenarios and estimate the frequency and severity of signs and symptoms of acute pesticide poisoning. The methodology is more or less standardised, but variations can be introduced to account for specific local conditions and/or explore specific issues in more detail. In remote, rural communities retrospective, self-reported injury histories are often the only practical source of information available on incidents of pesticide poisoning. However, retrospective studies are subject to recall bias and so we considered the likely accuracy and direction of bias of the results. Retrospective, self-reported injury histories are commonly used for reporting sports injuries over a 12 month sporting season. A study of the accuracy of the method (Gabbe 34 et al., 2003) showed that participants were able to recall the number of injuries and the body region affected with a high degree of accuracy over a 12 month recall period. They were less accurate in their recall of detailed diagnoses beyond a 2 month period but their ability to recall these details was improved when a clear definition of the injury was reported. The recall bias over 12 months tended to lead to under-reporting of incidents, and would therefore lead to a conservative estimate of the scale of injury. A study by Jenkins 35 et al., 2002, considered three studies of time-dependent memory recall and found a more significant drop in reported incidents beyond a two month period. Their conclusion was that recall periods of greater than 2 months are likely to significantly underestimate injury rates. A study of the effects of recall on reporting injury and poisoning episodes in the National Health Interview Survey in the United States (Warner 36 et al., 2005) also found a significant drop in the number of reported incidents over time and pointed out that survey approaches with longer recall reference periods must accept the trade-off of loss of episodes as a result of forgotten events versus increased sample sizes due to the longer periods. The PAN UK team took the view that the trade-off was worthwhile in this case because: 6 6

Recall bias tends to give a conservative result

The seasonality of pesticide use means that collecting reports of APP over a 12 month period gives more comparable results (similar rationale to the sports injury surveys over a 12 month sporting season described above) For the purposes of the surveys, acute pesticide poisoning is defined as any symptom or health effect resulting from exposure to a pesticide within 24 hours of pesticide use. Existing tools and common signs and symptoms of acute pesticide poisoning were used as a starting point (CPAM 37 , Murphy et al., 2002 38 , Thundiyil 2 et al., 2008, Persson et al., 1998 39 ). Signs and symptoms that can only be determined in a clinical setting were eliminated and descriptions were adapted into simpler language that could be understood by non-clinicians. The final list is provided in Table 1. The interviewees are also asked about the frequency of incidents over the previous 12 months in order to capture information on the cumulative frequency of such episodes.

TABLE 1. SURVEY QUESTIONS CONCERNING SIGNS AND SYMPTOMS OF ACUTE PESTICIDE POISONING

After exposure to pesticides do you notice any unusual signs or symptoms? (i.e. signs and symptoms that you do not usually suffer from)

How soon after the pesticide exposure do you experience signs/ symptoms? (hours) Headache Convulsion Dizziness Shortness of breath Unusual heart rhythm Memory loss Tremor Blurred vision Excessive sweating Insomnia Weakness Cough Skin irritation Nausea Vomiting Diarrhoea Other (please describe)

How often has this type of incident occurred in the

IF NO: PLEASE GO TO QUESTION 2.28 IF YES: please tick all that apply

Eye irritation Fever last 12 months?

Responses that are longer than 24 hours are not included in the estimated APP%

All participants are farmers or farm workers in the target area. Selection criteria vary somewhat, depending on the purpose of the survey (details provided in case studies below). In each country the questionnaire is translated into the most appropriate language. A local survey team is trained and observed conducting the survey, after which any problems or queries are discussed. The teams are alerted to issues of confidentiality and ethical standards, including making clear the purpose of the data and how it may be used to participants and survey teams are provided with a short script to use when introducing the survey. To the extent possible, surveys are conducted without bystanders present and at a location and time that are convenient for the participant. It is particularly important to ensure that farm workers are able to answer openly without concerns that they will be penalised by their employer for participating. The survey is tested on a small scale during training to ensure that the meaning of questions is clear and that the questions are relevant in the context. It is then refined before rolling out to the target population. The survey data can be disaggregated in a variety of ways, including by age, gender, farm size, farm worker or farm owner and, where appropriate, language(s) spoken. Strong efforts are made to validate information concerning any product(s) being reported in relation to poisoning incidents, including checking the product label where available and checking details of available products with local retailers.

Ideally, batches of approximately 20 completed questionnaires are shared with the PAN UK team as the field work progresses, so that errors can be found and explained to the field team as the data collection continues. The surveys were completed on paper or on excel spreadsheets on laptops, depending on the context. For future studies, PAN UK is currently trialling an app-based system.

Photo: Handling pesticides without protection in Ethiopia - credit PAN Ethiopia