The banning of bromacil in Costa Rica

Bromacil was introduced at the beginning of the 1960s for PRE and early POST control of grasses and broadleaf weeds, particularly in citrus (Rutaceae spp.) orchards and pineapple [Ananas comosus (L.) Merr.] plantations as well as in noncultivated areas. Both the acidic form of bromacil and its lithium salt are highly soluble in water; the herbicide is moderately to highly persistent in the soil with a half-life from 60 d to 8 mo and is prone to percolate in the soil and reach groundwater. In Costa Rica, bromacil was registered for both citrus and pineapple, but in recent years its major use has been in pineapple. An average of 60,000 kg of active bromacil per year were imported before its banning in 2017. Pineapple is grown in more than 40,000 ha; the recommended rate of bromacil was 1.6 to 3.2 kg ha−1. In a survey conducted by the National University between 2001 and 2004, bromacil was the most frequently found pesticide, at levels between 0.5 and 20 µg L−1, in water springs and wells in the pineapple-growing area of the Caribbean side of Costa Rica. Further studies conducted more recently also documented the presence of bromacil in the ground and surface water in areas where pineapple is planted. The local standard for the quality of drinking water of 2015 established maximum acceptable values of 0.1 µg L−1 and 0.5 µg L−1 for a single pesticide and for the sum of all pesticides present, respectively, but it was amended for bromacil to comply with requirements determined by the Constitutional Court to “non-detectable by method.” This paper provides an account of the scientific and administrative considerations for the banning of bromacil that occurred on May 24, 2017.