Paraquat product stewardship

A village training sessionParaquat product stewardship starts well before the product comes to market with thorough scientific evaluation and review of the extensive database by regulators. This stewardship has continued for more than 40 years and includes monitoring, ongoing research, scientific literature review, and regular consultation with governments, regulatory bodies, food companies, non-governmental organizations (NGOs) and farmers to ensure that their concerns are understood and addressed. Those involved in ensuring that all approaches to crop protection are safe, effective and sustainable should visit the Stewardship Community website.

Health-monitoring studies

Stewardship efforts related to paraquat include extensive studies to assess the safety in the use of paraquat. Results of these programs have confirmed that paraquat is safe when used according to straight-forward label instructions. A great deal is known about the likely effects of paraquat on users and hence the way to manage and avoid incidents. Paraquat has almost no vapor pressure and spray droplets are too large to enter the lung and is poorly absorbed through the human skin (the predominant route of exposure in occupational use).

Studies on the effects from day-to-day use

Effects from contact with paraquat during spray operations can occur due to an irritant action of paraquat as a result of poor working practice and hygiene (Howard et al, 1981). However, surveys interviewing smallholder farmers in Malaysia (Whitaker, 1989a), Central America (Whitaker, 1989b) and Thailand (Whitaker et al., 1993) showed that, in general, farmers were aware of the potentially adverse effects of exposure and the need for caution when handling pesticides including paraquat. Spray practices and standards of personal hygiene were generally adequate, although better adherence to PPE recommendations for all CPPs, in particular, the wider use of hand and eye protection when handling the concentrate, was needed. More recently, a Vietnamese Ministry of Health Pesticide Safety Study (2001) found occupational incidents for paraquat to be in the lower quartile group of all pesticides

Effects from long-term use have also been studied

There is a substantial body of evidence in the medical literature, which has accumulated over decades, regarding the question of long-term effects from occupational exposure to paraquat. Examples of these studies include: "Malaysia oil palm plantation workers" – British Journal of Industrial Medicine, 1980. This study concluded that: “Long term Paraquat spraying at the concentrations used produced no quantifiable harmful effects as measured by the indices selected for this study.” "Sri Lanka tea plantation workers" – British Journal of Industrial Medicine, 1993. This study concluded that: “Long term spraying of Paraquat produced no adverse health effects in particular no damage attributes to the occupational use of the herbicide.” All studies agree that under the normal, typical use conditions in developing countries there is no evidence from medical examinations, chest radiography, spirometry or gas transfer measurements, that paraquat causes any long-term health effects. Two investigations (Castro- Gutierrez et al, 1997 and Dalvie et al, 1999) claim to have found adverse health effects either in symptom reporting or in exercise-induced oxygen desaturation. However, there are serious methodological concerns over both of these findings, and they contrast with other objective measurements in the same studies showing no adverse health effects. In order to fully investigate these effects, workers in coffee, banana, and oil palm plantations in Costa Rica were studied by Professor M. Schenker, from the University of California in Davis, CA, USA, during 2001-2002. This is the largest-ever health monitoring study on paraquat-exposed workers. No clinically significant differences were detected in the respiratory function of exposed or non-exposed workers in all major outcome measures. This indicates that paraquat is not associated with the development of restrictive or obstructive lung disease and supports the continued safe use of paraquat under existing label conditions. (Schenker MB et al 2004)

Summary

The above work suggests that in day-to-day use paraquat can be and is being used safely. In long-term use workers’ health is not adversely affected by paraquat.

Rules for safe use

As with all pesticides, normal user precautions need to be taken when using and handling paraquat. Put simply, these are:
  1. Exercise caution at all time
  2. Read and understand the product label
  3. Ensure good personal hygiene
  4. Ensure care and maintenance of application equipment
  5. Use personal protective clothing and equipment (PPE) where required
For more details on training in the Five Golden Rules for safe use of CPPs click here.

Labels and Pictograms

Labels are an important source of information for farmers on how to use and apply products in a way that is effective against the target pest, yet doesn't pose unnecessary risks for people or the environment. When used according to the instructions provided by leading manufacturers on every package, paraquat poses no risk to farmers, society or the environment. However, in some developing countries, low levels of literacy may mean some farmers can't read the label. This has led to the development and widespread adoption of pictograms showing farmers how to prepare and use products safely, which are now used in developing countries to support the text label.

Accidental and deliberate ingestion

Strong stewardship actions to prevent accidental and deliberate swallowing of paraquat have led to the development of:
  • Clear direction to encourage growers to securely lock away all chemical
  • A Paraquat Treatment booklet and urine testing kits
  • Training in treating cases of swallowing
  • Identification of Fullers Earth and activated charcoal as effective treatments for ingestion. Provision of free diagnosis and treatment kits has been a feature for many years by the leading paraquat manufacturer, Syngenta.
  • Contribution to suicide prevention initiatives with global and local suicide prevention agencies encouraging safe and secure storage.
For a more complete understanding of treatment options and how the paraquat mechanism affects the human body, refer to the following website, which contains material jointly produced by members of the Health Assessment and Environmental Safety Department of Syngenta and the Medical Toxicology Unit, Guy's & St Thomas' Hospital NHS Trust, London, UK: http://www.syngenta.com/global/corporate/en/pqmedguide/Pages/index.aspx Commentators have noted the beneficial effect of these stewardship activities in countries such as Malaysia and Costa Rica (Sabapathy, 1995; Wesseling et al, 1997).  A paper from the National Poisons Centre in the UK noted in 2001 that “most of these cases (mistaken ingestion) occurred in the early 1980s with the last one recorded in 1992, confirming the virtual disappearance of accidental fatalities since their peak in the early 1970s” (Northall and Wilks, 2001).