Fertilisation of agricultural soils with municipal biosolids: Glyphosate and aminomethylphosphonic acid inputs to Québec field crop soils

Municipal biosolids (MBS) are suggested to be abundant, sustainable, inexpensive fertilisers, rich in phosphorus and nitrogen. However, MBS can also contain glyphosate and phosphonates that can degrade to AMPA. Glyphosate-based herbicides (GBH) are used in field crops all over the world. Most glyphosate generally degrades within a few weeks, mainly as aminomethylphosphonic acid (AMPA). AMPA is more persistent than glyphosate, and can accumulate from one crop year to the next. AMPA is phytotoxic even to glyphosate-resistant crops. The aims of this study were to assess whether MBS applications constitute: 1) an additional source of glyphosate and AMPA to agricultural soils with respect to GBH, 2) a significant source of trace metals, and 3) a partial replacement of mineral fertilisation while maintaining similar yields. To this end, four experimental agricultural sites were selected in Québec (Canada). Soil samples (0-20 cm) were collected to estimate the as yet unmeasured contribution of MBS application to glyphosate and AMPA inputs in agricultural soils. MBS applied in 2021 and 2022 had mean concentrations of 0.69 ± 0.53 μg glyphosate/dry g and 6.26 ± 1.93 μg AMPA/dry g. Despite the presence of glyphosate and AMPA in MBS, monitoring of these two compounds in corn and soybean crops over two years showed no significant difference between plots treated with and without MBS applications. For the same site, yields measured at harvest were similar between treatments. MBS application could thus represent a partial alternative to mineral fertilisers for field crops, while limiting the economic and environmental costs associated with their incineration and landfilling. It is also an economic advantage for agricultural producers given the possibility of using fewer mineral fertilisers and therefore reducing the environmental impact of their use.

In vivo estrogenicity of glyphosate, its formulations, and AMPA on transgenic zebrafish (Danio rerio) embryos

In this study, the disrupting effects of glyphosate (GLY), aminomethylphosphonic acid (AMPA), and three glyphosate-based herbicides (GBHs) on vitellogenesis in a non-concentration-dependent manner are reported for the first time in 120 h of acute exposure of zebrafish at environmentally relevant concentrations. GBHs are commonly used worldwide in weed control management. Due to their extensive application, they frequently occur in aquatic ecosystems and may affect various organisms. The active substance GLY and its major by-product, AMPA, are the most thoroughly studied chemicals; however, the adverse effects of the complex formulas of GBHs with diverse and unknown content of co-formulants are still not sufficiently researched. This study focused on the embryotoxicity, sublethal malformations, and estrogenic potency of GLY, AMPA, and four commonly used GBHs on zebrafish embryos using a wild type and an estrogen-sensitive, transgenic zebrafish line (Tg(vtg1:mCherry)). After 120 h of exposition, AMPA did not cause acute toxicity, while the LC50 of GLY was 160 mg/L. The GBHs were more toxic with LC50 values ranging from 31 to 111 GLY active equivalent (a.e.) mg/L. Exposure to 0.35-2.8 mg/L GBHs led to sublethal abnormalities: typical symptoms were structural deformation of the lower jaw and anomalies in the olfactory region. Deformity rates were 10-30% in the treated groups. In vivo, fluorescently expressed vtg1 mCherry protein in embryonic liver was detected by a non-invasive microscopic method indicating estrogenic action through vitellogenin production by GLY, AMPA, and GBHs. To confirm the in vivo findings, RT-qPCR method was performed to determine the levels of the estrogenicity-related vtg1 mRNA. After 120 h of exposure to GLY, AMPA, and three GBHs at a concentration of 0.35 mg/L, the expression of vtg1 gene was significantly up-regulated. Our results highlight the risk that short-term GLY and GBH exposure can cause developmental malformations and disrupt the hormonal balance in zebrafish embryos.

Perinatal exposure to high concentration glyphosate-based herbicides induces intestinal apoptosis by activating endoplasmic reticulum stress in offspring

Glyphosate-based herbicides (GBHs), the most widely used pesticide worldwide, have been reported to impair organ function in humans and animals. However, research on the effect of maternal GBHs exposure on the intestinal health of offspring has received little attention. Based on the glyphosate limits defined by Codex Alimentarius Commission and European Food Safety Authority, this study established pregnant sow exposure models to investigate the influence of low (L-GBHs, 20 mg/kg) and high concentration GBHs (H-GBHs, 100 mg/kg) on the intestinal health of offspring and proposed the protective mechanism mediated by betaine. The results showed that the intestinal morphology and barrier function of suckling piglets were damaged in the H-GBHs group. H-GBHs increased the activity of glutathione peroxidase (GPX) and levels of methane dicarboxylic aldehyde (MDA), hydrogen peroxide (H₂O₂) and inflammatory factors (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10)) in suckling piglets and activated Nrf2-mediated antioxidant signaling pathway. Subsequently, we found that exposure to H-GBHs triggered endoplasmic reticulum stress (ERS) and further induced apoptosis by upregulating the expression of Bcl-2-associated X protein (Bax), Caspase3, Caspase9 and Caspase12. Moreover, H-GBHs exposure perturbed mitochondrial membrane fusion and electron transport in mitochondrial respiratory chains by increasing the mRNA expression of mitofusin-2 (MFN2) and succinate dehydrogenase subunit A (SDHA), causing mitochondrial dysfunction. Dietary supplementation with betaine provided modest protection against GBHs-induced intestinal damage in suckling piglets. These findings reveal the mechanism of GBHs-induced intestinal damage in offspring, improving our understanding of the risk of GBHs exposure in pregnant women and suggesting the potential protective effects of betaine against GBHs poisoning.

Maternal exposure to a glyphosate-based herbicide impairs placental development through endoplasmic reticulum stress in mice

Glyphosate-based herbicides (GBHs) are the most widely used agrochemicals worldwide, increasing the risk of their occurrence in the environment. This study aimed to explore effects and mechanisms of GBH exposure on placental development in vivo during pregnancy in mice. Pregnant mice received GBH by gavage at 0, 5, and 50 mg⋅kg^-1⋅day^-1 doses from gestational day (GD) 1 to GD 13 and were sacrificed on GD 13 or GD19. Our data indicated that GBH administration significantly increased the number of resorbed fetuses, reduced the weight of fetuses and placentas, and inhibited placental growth, as evident from decreased placental total area and spongiotrophoblast area on GD 19. GBH treatment also inhibited proliferation and induced apoptosis of placenta via upregulation of Bax, cleaved caspase-3 and -12 expression, and downregulation of B cell lymphoma (Bcl)-2 expression. Further study showed that GBH exposure significantly increased expression levels of glucose-regulated protein 78 (GRP78), protein kinase RNA-like endoplasmic reticulum kinase (PERK), and C/EBP homologous protein (CHOP) mRNAs and proteins and triggered oxidative stress in placenta on GD 13 and GD 19. In conclusion, our findings suggest that maternal exposure to GBH can impair placental development through the endoplasmic reticulum stress-mediated activation of GRP78/PERK/CHOP signaling pathway in mice.

Perinatal exposure to glyphosate-based herbicides impairs progeny health and placental angiogenesis by disturbing mitochondrial function

Glyphosate-based herbicides (GBHs) are the most widely used pesticide worldwide and can provoke placental injury. However, whether and how GBHs damage angiogenesis in the placenta is not yet known. This work evaluated the safety of glyphosate on pregnant sows based on the limit level by governments and investigated the effects and mechanism of Low-GBHs (20 mg/kg) and High-GBHs (100 mg/kg) exposure on placental angiogenesis. Results showed that gestational exposure to GBHs decreased placental vessel density and cell multiplication by interfering with the expression of VEGFA, PLGF, VEGFr2 and Hand2 (indicators of angiogenesis), which may be in relation to oxidative stress-induced disorders of mitochondrial fission and fusion as well as the impaired function of the mitochondrial respiratory chain. Additionally, GBHs destroyed barrier function and nutrient transport in the placenta, and was accompanied by jejunum oxidative stress in newborn piglets. However, GBHs exposure had no significant differences on sow reproductive performance. As a natural antioxidant, betaine treatment protected placenta and newborn piglets against GBHs-induced damage. In conclusion, GBHs impaired placental angiogenesis and function and further damaged the health of postnatal progeny, these effects may be linked to mitochondrial dysfunction. Betaine treatment following glyphosate exposure provided modest relief.

Glyphosate-based herbicides: Evidence of immune-endocrine alteration

Glyphosate (G) is the active ingredient of the most widely used herbicide products. It targets the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), which lacks in humans, suggesting to confer a low mammalian toxicity to G-based herbicides (GBHs). Despite this, the use of G is currently under intense debate. Many studies indicating its hazard and toxicity on non-target organisms are emerging, and associations between GBHs and immune-endocrine disturbances have been described. This review aims to investigate, based on recent epidemiological studies and studies performed in vitro and in vivo in animals, the possible association between GBHs and immune-endocrine alterations. Published data suggest that GBHs have endocrine disrupting potentiality targeting sex and thyroid hormones, although its relevance for humans will require further investigations. Evidence of immunotoxicity are limited compared to those on endocrine effects, but overall highlight possible noxious effects, including lung inflammation and rhinitis. An attractive hypothesis could be the one that connects microbiota dysbiosis with possible immune-endocrine outcomes. Indeed, several intestinal microorganisms express the enzyme EPSPS and, studies are emerging that highlight a possible G-induced dysbiosis. Considering the wide use of GBHs in agriculture, further studies investigating their noxious effects at levels relevant for human exposure should be performed. A critical analysis of emerging evidence of G toxicity is required to better characterize its safety profile. In addition, attention should be paid to the differences between G alone and its formulations, which, containing substances able to increase G absorption, may present a different toxicity profile.

Bacterial isolates from Argentine Pampas and their ability to degrade glyphosate

Glyphosate is a synthetic phosphonate compound characterized by a carbon‑phosphorus bond. Glyphosate based herbicides (GBH) are widely distributed in most of the economically productive lands in which crop production is mainly based on glyphosate-resistant genetically modified plants. Naturally, glyphosate is remediated by soil microorganisms, which accelerate its degradation. Technology based on microorganisms is considered highly efficient, low-cost and eco-friendly to remediate contaminated environments, denoting the importance of characterizing new bacterial strains able to degrade glyphosate to perform its bioremediation. In this work, 13 different bacterial strains able to grow in GBH as only phosphorous source were isolated from different environmental samples from the Argentine vastly productive glyphosate-resistant soybean crop area. These strains were identified and they belong to the genera Acinetobacter, Achromobacter, Agrobacterium, Ochrobactrum, Pantoea and Pseudomonas. Their ability to grow and consume GBH, glyphosate or the aminomethylphosphonic acid (AMPA), another phosphonate derived from glyphosate degradation, was evaluated. The best degradation performance was observed for bacteria from the genera Achromobacter, Agrobacterium and Ochrobactrum. The genome of the highly efficient GBH degrader Agrobacterium tumefaciens CHLDO was sequenced revealing the presence of a phn cluster, responsible for phosphonate metabolization. Expression analysis of A. tumefaciens CHLDO phn genes in the presence of 1.5 mM GBH compared to inorganic phosphorous showed that most of them are highly expressed during growth in the presence of the herbicide, suggesting a strong participation of phn cluster in GBH degradation. The importance of discovering new bacterial strains and the value of deciphering molecular determinants of GBH degradation give promising tools for bioremediation techniques to be used in glyphosate-contaminated environments is discussed.

Effects of commercial formulations of glyphosate on marine crustaceans and implications for risk assessment under temperature changes

Glyphosate-based formulations are the most commonly used herbicides worldwide with the risk of potential contamination of aquatic bodies. The present study assessed the response of four marine crustaceans to three different brands of herbicides Roundup®Platinum, Efesto® and Taifun® MK CL.T, under two selected temperatures of 20 °C and 30 °C. The harpacticoid copepod Tigriopus fulvus, the anostracan Artemia franciscana, the amphipod Corophium insidiosum and the isopod Sphaeroma serratum were chosen as testing organisms. Effects of herbicides and temperatures were assessed by estimating lethal concentrations. The results showed that the high temperature rises the toxicity of glyphosate with an increase of mortality of all the tested species. This is an important aspect for future risk assessments of pesticides under global climate change scenarios. Efesto® resulted the most toxic brand, showing C. insidiosum the most sensitive with 96 h-LC50 values of 3.25 mg/L acid equivalent (a.e.) at 30 °C and 7.94 mg/L a.e. at 20 °C followed by T. fulvus while A. franciscana and S. serratum were the less sensitive. This study provides important information for assessing the toxic effects of three different brands of glyphosate-based herbicides on non-target marine organisms suggesting that they should be carefully managed to minimize any negative impact on marine organisms.

Influence of a glyphosate-based herbicide on growth parameters and aflatoxin B1 production by Aspergillus section Flavi on maize grains

Glyphosate-based herbicides (GBH) are the main pesticides applied worldwide on maize production. Glyphosate-resistant weeds led to the repeated application of high doses of the pesticide. In addition to environmental conditions, the presence of GBH affects the development of Aspergillus species and aflatoxin B1 (AFB1) production under in vitro conditions. The aim of this work was to evaluate the influence of a commercial GBH on growth and AFB1 production by Aspergillus flavus and Aspergillus parasiticus strains under different water activity (aW) conditions. The following concentrations of active ingredient glyphosate were evaluated: 20, 50, 200 and 500mM. The lag phase prior to growth and growth rate did not change at 20 and 50mM (that is, at field recommended doses) at 0.98 and 0.95 aW; however, at increasing GBH concentrations, between 200 and 500mM, the growth rate decreased at all aW conditions. In general, as the GBH concentration increased, AFB1 production decreased. However, a significant increase in toxin accumulation was found only at one of the aW conditions (0.95) at 21 days with 50mM of GBH in A. flavus and 20 and 50mM of GBH in A. parasiticus. These results show that, even though Aspergillus section Flavi growth did not increase, AFB1 production increased on maize grains at GBH concentrations similar to those of field recommended doses under favorable water availability and temperature conditions.

Intranasal glyphosate-based herbicide administration alters the redox balance and the cholinergic system in the mouse brain

Pesticide exposure is associated with cognitive and psychomotor disorders. Glyphosate-based herbicides (GlyBH) are among the most used agrochemicals, and inhalation of GlyBH sprays may arise from frequent aerial pulverizations. Previously, we described that intranasal (IN) administration of GlyBH in mice decreases locomotor activity, increases anxiety, and impairs recognition memory. Then, the aim of the present study was to investigate the mechanisms involved in GlyBH neurotoxicity after IN administration. Adult male CF-1 mice were exposed to GlyBH IN administration (equivalent to 50 mg/kg/day of Gly acid, 3 days a week, during 4 weeks). Total thiol content and the activity of the enzymes catalase, acetylcholinesterase and transaminases were evaluated in different brain areas. In addition, markers of the cholinergic and the nigrostriatal pathways, as well as of astrocytes were evaluated by fluorescence microscopy in coronal brain sections. The brain areas chosen for analysis were those seen to be affected in our previous study. GlyBH IN administration impaired the redox balance of the brain and modified the activities of enzymes involved in cholinergic and glutamatergic pathways. Moreover, GlyBH treatment decreased the number of cholinergic neurons in the medial septum as well as the expression of the α7-acetylcholine receptor in the hippocampus. Also, the number of astrocytes increased in the anterior olfactory nucleus of the exposed mice. Taken together, these disturbances may contribute to the neurobehavioural impairments reported previously by us after IN GlyBH administration in mice.

Glyphosate but not Roundup® harms earthworms (Eisenia fetida)

Glyphosate is the active ingredient in Roundup® formulations. While multiple studies have documented the toxicity, environmental persistence, and tendency to spread for glyphosate and Roundup®, few studies have compared the toxicity of glyphosate-based formulations to the toxicity of pure glyphosate for soil invertebrates, which contact both the herbicide and the formulations. Hundreds of formulations exist; their inert ingredients are confidential; and glyphosate persists in our food, water, and soil. In this experiment, we held glyphosate type and concentration constant, varying only formulation. Using Roundup Ready-to-Use III®, Roundup Super Concentrate®, and pure glyphosate, we delivered 26.3 mg glyphosate in the form of isopropylamine salt per kg of soil to compost worms (Eisenia fetida). We found that worms living in soil spiked with pure glyphosate lost 14.8-25.9% of their biomass and survived a stress test for 22.2-33.3% less time than worms living in uncontaminated soil. Worms living in soil spiked with Roundup Ready-to-Use III® and Roundup Super Concentrate® did not lose body mass and survived the stress test as well as worms living in uncontaminated soil. No contaminant affected soil microbial or fungal biomass over the 40-day period of this experiment. We suggest that the nitrates and phosphates in the formulations offset the toxic effects of glyphosate by spurring microbial growth and speeding glyphosate degradation. We also found a 26.5-41.3% reduction in fungal biomass across all treatments over the course of this experiment, suggesting that the worms consumed fungi and spores.

Exposure to Roundup® affects behaviour, head regeneration and reproduction of the freshwater planarian Girardia tigrina

The demand of glyphosate-based herbicides including Roundup® is rising in the tropics due to increase occurence of glyphosate-resistant weeds that require higher herbicide application rates but also because of their use associated with genetically engineered, glyphosate-tolerant crops. Consequently, there is now an excessive use of glyphosate in agricultural areas with potential adverse effects also for the surrounding aquatic environments. This study aimed to determine the sensitivity of the freshwater planarian Girardia tigrina to acute and chronic exposures of Roundup®. Planarians were exposed to a range of lethal and sub-lethal concentrations of Roundup® to determine the median lethal concentration (LC50) concerning its active ingredient glyphosate and also effects on locomotor velocity (pLMV), feeding rate, regeneration, reproductive parameters and morphological abnormalities. Regeneration endpoints included length of blastema and time for photoreceptors and auricles regeneration after decapitation, while effects on reproduction were assessed measuring fecundity (number of deposited cocoons) and fertility (number of hatchlings) over five weeks of exposure to glyphosate. The estimated 48 h LC50 of was 35.94 mg glyphosate/L. Dose dependent effects were observed for feeding, locomotion and regeneration endpoints with Lowest observed effect concentration (LOEC) values as low as 3.75 mg glyphosate/L. Chronic exposures to environmentally relevant concentrations of glyphosate significantly impaired fecundity and fertility rates of exposed planarians (median effective concentration, EC50 = 1.6 mg glyphosate/L for fecundity and fertility rates). Our results show deleterious effects of Roundup® on regeneration, behavior and reproduction of freshwater planarians and add important ecotoxicological data towards the environmental risk assessment of glyphosate-based herbicide in freshwater ecosystems.

A commercial Roundup® formulation induced male germ cell apoptosis by promoting the expression of XAF1 in adult mice

Roundup® is extensively used for weed control worldwide. Residues of this compound may lead to side effects of the male reproductive system. However, the toxic effects and mechanisms of Roundup® of male germ cells remain unclear. We aimed to investigate the apoptosis-inducing effects of Roundup® on mouse male germ cells and explore the role of a novel tumor suppressor XAF1 (X-linked inhibitor of apoptosis-associated factor 1) involved in this process. We demonstrated that Roundup® can impair spermatogenesis, decrease sperm motility and concentration, and increase the sperm deformity rate in mice. In addition, excessive apoptosis of germ cells accompanied by the overexpression of XAF1 occurred after Roundup® exposure both in vitro and in vivo. Furthermore, the low expression of XIAP (X-linked inhibitor of apoptosis) induced by Roundup® was inversely correlated with XAF1. Moreover, the knockdown of XAF1 attenuated germ cell apoptosis, improved XIAP expression and inhibited the activation of its downstream target proteins, caspase-3 and PARP, after Roundup® exposure. Taken together, our data indicated that XAF1 plays an important role in Roundup®-induced male germ cell apoptosis. The present study suggested that Roundup® exposure has potential negative implications on male reproductive health in mammals.

Impacts of glyphosate-based herbicides on disease resistance and health of crops: a review

Based on experimental data from laboratory and field, numerous authors have raised concern that exposure to glyphosate-based herbicides (GBHs) may pre-dispose crops to damage by microbial pathogens. In this review, we distinguish and evaluate two principal pathways by which GBHs may affect the susceptibility of crops to disease: pathway 1-via disruptions to rhizosphere microbial ecology, and pathway 2-via restriction of nutrients to crops. We conclude that GBHs have the potential to undermine crop health in a number of ways, including: (i) impairment of the innate physiological defences of glyphosate-sensitive (GS) cultivars by interruption of the shikimic acid pathway; (ii) impairment of physiological disease defences has also been shown to occur in some glyphosate-resistant (GR) cultivars, despite their engineered resistance to glyphosate's primary mode of action; (iii) interference with rhizosphere microbial ecology (in particular, GBHs have the potential to enhance the population and/or virulence of some phytopathogenic microbial species in the crop rhizosphere); and finally, (iv) the as yet incompletely elucidated reduction in the uptake and utilisation of nutrient metals by crops. Future progress will best be achieved when growers, regulators and industry collaborate to develop products, practices and policies that minimise the use of herbicides as far as possible and maximise their effectiveness when used, while facilitating optimised food production and security.

Exposure to a glyphosate-based herbicide during pregnancy and lactation induces neurobehavioral alterations in rat offspring

The impact of sub-lethal doses of herbicides on human health and the environment is a matter of controversy. Due to the fact that evidence particularly of the effects of glyphosate on the central nervous system of rat offspring by in utero exposure is scarce, the purpose of the present study was to assess the neurobehavioral effects of chronic exposure to a glyphosate-containing herbicide during pregnancy and lactation. To this end, pregnant Wistar rats were exposed through drinking water to 0.2% or 0.4% of a commercial formulation of glyphosate (corresponding to a concentration of 0.65 or 1.30g/L of glyphosate, respectively) during pregnancy and lactation and neurobehavioral alterations in offspring were analyzed. The postnatal day on which each pup acquired neonatal reflexes (righting, cliff aversion and negative geotaxis) and that on which eyes and auditory canals were fully opened were recorded for the assessment of sensorimotor development. Locomotor activity and anxiety levels were monitored via open field test and plus maze test, respectively, in 45- and 90-day-old offspring. Pups exposed to a glyphosate-based herbicide showed early onset of cliff aversion reflex and early auditory canal opening. A decrease in locomotor activity and in anxiety levels was also observed in the groups exposed to a glyphosate-containing herbicide. Findings from the present study reveal that early exposure to a glyphosate-based herbicide affects the central nervous system in rat offspring probably by altering mechanisms or neurotransmitter systems that regulate locomotor activity and anxiety.

Effects of glyphosate-based herbicides on survival, development, growth and sex ratios of wood frogs (Lithobates sylvaticus) tadpoles. I: chronic laboratory exposures to VisionMax®

The purpose of this study was to determine if chronic exposure to the glyphosate-based herbicide VisionMax(®) affects the survival, development, growth, sex ratios and expression of specific genes involved in metamorphosis of wood frog tadpoles (Lithobates sylvaticus). We hypothesized that exposure to this herbicide will affect developmental rates by disrupting hormone pathways, sex ratios and/or gonadal morphology. Tadpoles were chronically exposed in the laboratory from Gosner developmental stage 25 to 42 to four different concentrations of VisionMax(®) (ranging from 0.021 to 2.9 mg acid equivalents/L). Chronic exposures to VisionMax(®) had direct effects on the metamorphosis of L. sylvaticus tadpoles by decreasing development rates, however, there was a decrease in survival only in the group exposed to the highest dose of VisionMax(®) (2.9 mg a.e./L; from approximately 96% in the control group to 77% in the treatment group). There was a decrease in the number of tadpoles reaching metamorphic climax, from 78% in the control group to 42% in the VisionMax(®) (2.9 mg a.e./L) group, and a 7-day delay to reach metamorphic climax in the same treatment group. No effects of exposure on sex ratios or gonadal morphology were detected in tadpoles exposed to any of the concentrations of VisionMax(®) tested. Gene expression analyses in brain and tail tissues demonstrated that exposure to VisionMax(®) alters the expression of key genes involved in development. Results showed significant interaction (two-way ANOVA, P<0.05) between developmental Gosner stage and treatment in brain corticotropin-releasing factor, deiodinase type II (dio2) and glucocorticotiroid receptor (grII) and tail dio2 and grII. This demonstrates that mRNA levels may be differently affected by treatment depending on the developmental stage at which they are assessed. At the same time there was a clear dose-response effect for VisionMax(®) to increase thyroid hormone receptor β in tadpole brain (F(2,69)=3.475, P=0.037) and tail (F(2,69)=27.569, P<0.001), regardless of developmental stage. Interestingly, delays in development (or survival) were only observed in the group exposed to 2.9 mg a.e./L of VisionMax(®), suggesting that tadpoles need to be exposed to a "threshold" concentration of glyphosate-based herbicide to exhibit phenotypic observable effects. We suggest that the upregulation of genes that trigger metamorphosis following VisionMax(®) herbicide exposure might result from a compensatory response for the delays in development observed. Further studies are needed to determine if disruption of expression of these key genes leads to long-term effects when metamorphs reach adult stages.

Republished study: long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize

BACKGROUND

The health effects of a Roundup-tolerant NK603 genetically modified (GM) maize (from 11% in the diet), cultivated with or without Roundup application and Roundup alone (from 0.1 ppb of the full pesticide containing glyphosate and adjuvants) in drinking water, were evaluated for 2 years in rats. This study constitutes a follow-up investigation of a 90-day feeding study conducted by Monsanto in order to obtain commercial release of this GMO, employing the same rat strain and analyzing biochemical parameters on the same number of animals per group as our investigation. Our research represents the first chronic study on these substances, in which all observations including tumors are reported chronologically. Thus, it was not designed as a carcinogenicity study. We report the major findings with 34 organs observed and 56 parameters analyzed at 11 time points for most organs.

RESULTS

Biochemical analyses confirmed very significant chronic kidney deficiencies, for all treatments and both sexes; 76% of the altered parameters were kidney-related. In treated males, liver congestions and necrosis were 2.5 to 5.5 times higher. Marked and severe nephropathies were also generally 1.3 to 2.3 times greater. In females, all treatment groups showed a two- to threefold increase in mortality, and deaths were earlier. This difference was also evident in three male groups fed with GM maize. All results were hormone- and sex-dependent, and the pathological profiles were comparable. Females developed large mammary tumors more frequently and before controls; the pituitary was the second most disabled organ; the sex hormonal balance was modified by consumption of GM maize and Roundup treatments. Males presented up to four times more large palpable tumors starting 600 days earlier than in the control group, in which only one tumor was noted. These results may be explained by not only the non-linear endocrine-disrupting effects of Roundup but also by the overexpression of the EPSPS transgene or other mutational effects in the GM maize and their metabolic consequences.

CONCLUSION

Our findings imply that long-term (2 year) feeding trials need to be conducted to thoroughly evaluate the safety of GM foods and pesticides in their full commercial formulations.