Paraquat poisoning following the introduction of the European Union ban

Aim: The aim of this study was to examine and characterise all paraquat poisoning cases reported to the National Poisons Information Centre of Ireland (NPIC) over a 23-year period (1999- 2022), and to compare data from the periods before and after the implementation of the ban, to determine its impact.

Methods: This is a prospective observational national population study on consecutive human cases reported to the NPIC following the introduction of the EU paraquat ban. Since 01/01/1999, the NPIC prospectively collected data from all cases of paraquat poisoning for the purposes of a longitudinal epidemiological study of paraquat poisoning in Ireland. Thus, data that had already been collected prospectively in the pre-ban period (1999-2008) served as baseline comparative data for this observational study. Inclusion criteria consisted of all cases of ingestion of paraquat-containing products. Exclusion criteria consisted of cases of dermal, ocular and inhalational exposures only. Data collected included: patient demographics, exposure circumstances (classified as intentional/deliberate or unintentional based on the history provided at the time of the enquiry to the NPIC), product formulation, clinical features, detection of paraquat in biological fluids, and patient outcome (determined from follow-up telephone enquiries to the treating hospital). Our primary outcome measure was the observed effect of the EU paraquat ban on the incidence of paraquat poisoning cases in Ireland pre-ban and post-ban. Secondary measures included the circumstances (intentional versus unintentional, the type of product used pre and post ban), and the toxicity, morbidity and mortality of paraquat poisoning in Ireland.

Results: Prior to the introduction of the European ban (1999-2007), there were 95 cases of paraquat poisoning (70 intentional, 25 unintentional) with 33 fatalities. Following the ban (2008-2022), there were 11 cases of intentional poisoning with 4 fatalities, and no cases of unintentional poisoning. Since 2014, there have been no further poisoning cases reported in Ireland. A small reduction in the hospital mortality rate for intentional overdoses pre/post-ban was observed; 47.14% (33/70) for 9-years before the ban compared to 36.36% (4/11) following the paraquat ban. Whilst this small reduction in fatality rate was not clinically significant, the real-term fatality numbers were, with an observed reduction in fatalities from 33 in the nine years prior to the ban, to 4 in the fourteen years since the introduction of the EU ban. A comparison of the 3-year moving average number of paraquat poisoning cases indicated the EU paraquat ban significantly reduced the number of poisoning cases.

Discussion: Globally, public health measures that were introduced by manufacturers, policy makers and governments to ensure occupational safety, failed to prevent paraquat poisoning. In our study, paraquat poisoning resulted in significant morbidity and mortality especially with professional formulations, reflecting other epidemiological research findings. The majority of patients with a fatal outcome (24, 64.87%) died within 24-hours. Importantly, there were no further cases of unintentional paraquat ingestion following the European ban and the incidence of intentional poisonings was notably reduced. The evidence from this observational study demonstrates that the paraquat ban has been a successful public health measure in Ireland. The European Union legislation revoking paraquat’s licence was a successful public health intervention that eliminated unintentional paraquat exposures and effectively reduced the incidence of deliberate poisonings and fatalities in Ireland.