Transport of Glyphosate and Aminomethylphosphonic Acid under Two Soil Management Practices in an Italian Vineyard

Hotspots of soil pollution: Possible glyphosate and aminomethylphosphonic acid risks on terrestrial ecosystems and human health

The study presents a literature review of glyphosate (GLY) occurrence and its breakdown product, aminomethylphosphonic acid (AMPA), in soils worldwide, but with a specific focus on South America. In addition, an ecological risk approach based on the ecotoxicological endpoints for key soil biota (e.g., collembolans, and earthworms) assessed the impact of GLY and AMPA on these organisms. A generic probabilistic model for human health risk was also calculated for the different world regions. For what reports the risk for edaphic species and the level of pollution under the worst-case scenario, the South American continent was identified as the region of most concern. Nonetheless, other areas may also be in danger, but no risk could be calculated due to the lack of data. Since tropical countries are the top food exporters worldwide, the results obtained in this study must be carefully examined for their implications on a global scale. Some of the factors behind the high levels of these two chemicals in soils are debated (e.g., permissive protection policies, the extensive use of genetically modified crops), and some possible guidelines are presented that include, for example, further environmental characterisation and management of pesticide residues. The present review integrates data that can be used as a base by policymakers and decision-makers to develop and implement environmental policies.

Do commonly used herbicides (atrazine and glyphosate) have the potential to impair the contractions, prostaglandin releasing and conducting of oxytocin signal at the bovine cervix in vitro?

Glyphosate (Gly) and atrazine (Atr) are among the most commonly used herbicides in global agriculture. It was previously shown that both Atr and Gly impair the ovarian and uterine secretion of regulators of myometrial motility (oxytocin (OT) or prostaglandins (PGs)) in cows, and Atr can also decrease the force of contractions in strips from the uterine horn. Hence, the aim of this study was to compare the effects of Atr and Gly on the motor and secretory function of the bovine cervix in vitro as well as receptivity and signal transduction in cervical cell cultures. Cervical strips or cells obtained from cows before ovulation were treated with environmental doses of Atr or Gly (0.1-10 ng/ml) since these herbicides exerted no cytotoxic effect at a dose of 100 ng/ml. Only Atr increased the force of cervical contractions, while both Atr and Gly decreased the secretion of prostaglandins (PGs) without disturbing their synthesis. Moreover, Atr decreased the mRNA expression and protein level of oxytocin receptor (OTR), while Gly increased OTR protein levels. Both Atr and Gly decreased the contents of gap junction proteins (GAPs), Atr decreased the contents of second messengers (diacylglycerol - DAG, inositol-tris-phosphate - IP3), and Gly decreased the level of myosin light chain kinase (MLCK) but increased DAG levels. Atr directly enhanced the cervical strips contractions. Both herbicides disturbed cellular signalling and inhibited PGs secretion. It suggest that Atr and Gly have the potential to impair the activity of cervical cells in vitro, which might be followed by failure of maintenance with gestation.

The global environmental hazard of glyphosate use

Agricultural pesticides can become persistent environmental pollutants. Among many, glyphosate (GLP) is under particular scrutiny because of its extensive use and its alleged threats to the ecosystem and human health. Here, we introduce the first global environmental contamination analysis of GLP and its metabolite, AMPA, conducted with a mechanistic dynamic model at 0.5 × 0.5° spatial resolution (about 55 km at the equator) fed with geographically-distributed agricultural quantities, soil and biogeochemical properties, and hydroclimatic variables. Our analyses reveal that about 1% of croplands worldwide (385,000 km²) are susceptible to mid to high contamination hazard and less than 0.1% has a high hazard. Hotspots found in South America, Europe, and East and South Asia were mostly correlated to widespread GLP use in pastures, soybean, and corn; diffuse contributing processes were mainly biodegradation recalcitrance and persistence, while soil residue accumulation and leaching below the root zone contributed locally to the hazard in hotspots. Hydroclimatic and soil variables were major controlling factors of contamination hotspots. The relatively low risk of environmental exposure highlighted in our work for a single active substance does not rule out a greater recognition of environmental pollution by pesticides and calls for worldwide cooperation to develop timely standards and implement regulated strategies to prevent excess global environmental pollution.

Glyphosate affects the secretion of regulators of uterine contractions in cows while it does not directly impair the motoric function of myometrium in vitro

The effects of pure glyphosate and its most popular product (brand name: Roundup) on the secretion of hormones involved in the regulation of myometrial contractions as well as their direct effects on myometrial contractions were examined. Myometrial strips as well as uterine and ovarian cells were taken from cows during the oestrous cycle and they were treated with both compounds at concentrations from their environmental range. Glyphosate stimulated the secretion of oestradiol from granulosa cells while both herbicides increased and decreased oxytocin (OT) and progesterone secretion from luteal cells respectively. However only Roundup stimulated mRNA expression of the precursor of OT. Both compounds decreased the secretion of prostaglandins from endometrial cells while they exerted no effect on the basal and OT-stimulated force of myometrial contractions. The studied herbicides did not directly impair the motoric function of the myometrium. However our data indicate the potential of these compounds to disturb the secretory functions of the ovaries and uterus which can lead to the deregulation of uterine contractions and to the impairment of fertilisation or to difficulties in the maintenance of gestation.

Spatial glyphosate and AMPA redistribution on the soil surface driven by sediment transport processes - A flume experiment

This study investigates the influence of small-scale sediment transport on glyphosate and AMPA redistribution on the soil surface and on their off-site transport during water erosion events. Both a smooth surface (T1) and a surface with "seeding lines on the contour" (T2) were tested in a rainfall simulation experiment using soil flumes (1 × 0.5 m) with a 5% slope. A dose of 178 mg m-2 of a glyphosate-based formulation (CLINIC®) was applied on the upper 0.2 m of the flumes. Four 15-min rainfall events (RE) with 30-min interval in between and a total rainfall intensity of 30 mm h-1 were applied. Runoff samples were collected after each RE in a collector at the flume outlet. At the end of the four REs, soil and sediment samples were collected in the application area and in four 20 cm-segments downslope of the application area. Samples were collected according to the following visually distinguished soil surface groups: light sedimentation (LS), dark sedimentation (DS), background and aggregates. Results showed that runoff, suspended sediment and associated glyphosate and AMPA off-site transport were significantly lower in T2 than in T1. Glyphosate and AMPA off-site deposition was higher for T2 than for T1, and their contents on the soil surface decreased with increasing distance from the application area for all soil surface groups and in both treatments. The LS and DS groups presented the highest glyphosate and AMPA contents, but the background group contributed the most to the downslope off-site deposition. Glyphosate and AMPA off-target particle-bound transport was 9.4% (T1) and 17.8% (T2) of the applied amount, while water-dissolved transport was 2.8% (T1) and 0.5% (T2). Particle size and organic matter influenced the mobility of glyphosate and AMPA to off-target areas. These results indicate that the pollution risk of terrestrial and aquatic environments through runoff and deposition can be considerable.