RESUMO
Risk assessment of pesticide impacts on remote ecosystems makes use of model-estimated degradation in air. Recent studies suggest these degradation rates to be overestimated, questioning current pesticide regulation. Here, we investigated the concentrations of 76 pesticides in Europe at 29 rural, coastal, mountain, and polar sites during the agricultural application season. Overall, 58 pesticides were observed in the European atmosphere. Low spatial variation of 7 pesticides suggests continental-scale atmospheric dispersal. Based on concentrations in free tropospheric air and at Arctic sites, 22 pesticides were identified to be prone to long-range atmospheric transport, which included 15 substances approved for agricultural use in Europe and 7 banned ones. Comparison between concentrations at remote sites and those found at pesticide source areas suggests long atmospheric lifetimes of atrazine, cyprodinil, spiroxamine, tebuconazole, terbuthylazine, and thiacloprid. In general, our findings suggest that atmospheric transport and persistence of pesticides have been underestimated and that their risk assessment needs to be improved.
RESUMO
Placental syncytiotrophoblasts are known to express the efflux transporter proteins P-glycoprotein (ABCB1) and multidrug resistance-associated protein 2 (ABCC2), which are supposed to be a functional part of the human placental barrier. With advancing gestational age, expression of ABCB1 decreases progressively, whereas ABCC2 is more expressed. To evaluate to which extent they contribute to placental barrier function at term, permeability of talinolol, a substrate of both carriers, was measured using a validated human placenta perfusion model. We identified in randomized, crossover experiments a unidirectional transfer of talinolol in the fetomaternal direction because the maternofetal transfer was significantly lower (0.663 +/- 0.188 versus 0.394 +/- 0.067 relative to creatinine permeability, p = 0.012). Maternofetal permeability was increased by the ABCC2 inhibitor probenecid (0.59 +/- 0.15 versus 0.68 +/- 0.13, p = 0.028) and the nonspecific inhibitor verapamil (0.53 +/- 0.09 versus 0.66 +/- 0.16, p = 0.028) but was not influenced by the ABCB1 inhibitor valspodar (PSC833) (0.48 +/- 0.11 versus 0.46 +/- 0.09, p = 0.345). Genetic polymorphisms of ABCB1 and ABCC2 lacked significant influence on expression of the carriers and permeability of talinolol, respectively. In conclusion, maternofetal transfer of talinolol is restricted by a unidirectional process that is influenced by inhibitors of ABCC2.
