Distribution of Glyphosate in Chicken Organs and its Reduction by Humic Acid Supplementation

Assessment of glyphosate and its metabolites' residue concentrations in cultured African Catfish offered for sale in selected markets in Ibadan, Oyo State, Nigeria

Introduction: Glyphosate is a non-targeted organophosphate insecticide whose solubility and mobility in hydrophilic solvents enable its rapid leaching into the soil and subsequent contamination of ground and surface water and possible build-up in the aquatic food chain. Based on the public health importance of glyphosate in fish through consumption, it is crucial to determine the current residue concentration in culture Clarias gariepinus species. The aim of the present study is to evaluate glyphosate's residue concentrations and its metabolites in cultured African Catfish offered for sale in selected markets in Ibadan. Methods: A total of twenty-five (25) adult Clarias gariepinus (300 ± 50 g) were sourced from five (5) selected active fish markets (Ojoo, Iwo road, Eleyele, Challenge, and Apata) within the Ibadan metropolis. The collected fish tissue samples (liver, kidney, and spleen) were prepared for glyphosate residue concentration analysis using Liquid Chromatography (LC). Results: The results showed that glyphosate residues were recorded in all the seventy-five (75) fish tissue samples obtained from the selected fish markets in the Ibadan metropolis and all residue concentrations were above both the recommended Acceptable Daily Intake (ADI) of 1.0 mg/kg (1 × 10-3 mg/L) and Maximum Residue Limits (MRL) of 0.01 mg/kg (1 × 10-5 mg/L). Isopropylamine has the highest residue concentration followed by N-Phosphonomethyl and Aminomethylphosphonic Acid (AMPA), while N-Acetyl Glyphosate has the least residue concentration across the sampled markets. Discussion: The presence of residues of glyphosate and its metabolites in ready-to-eat fish calls for holistic, systematic, and effective risk management strategies towards monitoring pesticide/herbicide usage in aquaculture production and ensuring the provision of wholesome fish and fish products for the consumers.

Pesticide impacts on avian species with special reference to farmland birds: a review

For decades, we have observed a major biodiversity crisis impacting all taxa. Avian species have been particularly well monitored over the long term, documenting their declines. In particular, farmland birds are decreasing worldwide, but the contribution of pesticides to their decline remains controversial. Most studies addressing the effects of agrochemicals are limited to their assessment under controlled laboratory conditions, the determination of lethal dose 50 (LD₅₀) values and testing in a few species, most belonging to Galliformes. They often ignore the high interspecies variability in sensitivity, delayed sublethal effects on the physiology, behaviour and life-history traits of individuals and their consequences at the population and community levels. Most importantly, they have entirely neglected to test for the multiple exposure pathways to which individuals are subjected in the field (cocktail effects). The present review aims to provide a comprehensive overview for ecologists, evolutionary ecologists and conservationists. We aimed to compile the literature on the effects of pesticides on bird physiology, behaviour and life-history traits, collecting evidence from model and wild species and from field and lab experiments to highlight the gaps that remain to be filled. We show how subtle nonlethal exposure might be pernicious, with major consequences for bird populations and communities. We finally propose several prospective guidelines for future studies that may be considered to meet urgent needs.

Glyphosate-based herbicide formulations and reproductive toxicity in animals

The adoption of genetically engineered (GE) crops in agriculture has increased dramatically over the last few decades. Among the transgenic plants, those tolerant to the herbicide glyphosate are among the most common. Weed resistance to glyphosate-based herbicides (GBHs) has been on the rise, leading to increased herbicide applications. This, in turn, has led to increased glyphosate residues in feed. Although glyphosate has been considered to be generally safe to animal health, recent studies have shown that GBHs have potential to cause adverse effects in animal reproduction, including disruption of key regulatory enzymes in androgen synthesis, alteration of serum levels of estrogen and testosterone, damage to reproductive tissues and impairment of gametogenesis. This review emphasizes known effects of GBHs on reproductive health as well as the potential risk GBH residues pose to animal agriculture.

Estimated exposure to glyphosate in humans via environmental, occupational, and dietary pathways: an updated review of the scientific literature

Glyphosate is one of the most widely used herbicides in the world, but it has also been the focus of discussion and restrictions in several countries since it was declared 'probably carcinogenic to humans (Group 2A)' by the International Agency for Research on Cancer in 2015. Since that time, several regulatory agencies have reviewed the public literature and guideline studies submitted for regulatory purposes and have concluded that it is not a carcinogen, and revised acceptable daily intakes (ADIs) and the reference dose (RfD) have been published. Also, restrictions on use have been lifted in many locations. Risk assessment for any pesticide requires knowledge of exposure in humans and the environment, and this paper is an update on a previous review in 2016 and includes papers published after 2016. These exposure data for air, water, bystanders, the general public, domesticated animals, pets, and applicators were combined and compared to the revised exposure criteria published by regulatory agencies. In all cases, measured and estimated systemic exposures to glyphosate in humans and animals were less than the ADIs and the RfD. Based on this large dataset, these exposures represent a de minimis risk. © 2019 Society of Chemical Industry.

The evidence of human exposure to glyphosate: a review

BACKGROUND

Despite the growing and widespread use of glyphosate, a broad-spectrum herbicide and desiccant, very few studies have evaluated the extent and amount of human exposure.

OBJECTIVE

We review documented levels of human exposure among workers in occupational settings and the general population.

METHODS

We conducted a review of scientific publications on glyphosate levels in humans; 19 studies were identified, of which five investigated occupational exposure to glyphosate, 11 documented the exposure in general populations, and three reported on both.

RESULTS

Eight studies reported urinary levels in 423 occupationally and para-occupationally exposed subjects; 14 studies reported glyphosate levels in various biofluids on 3298 subjects from the general population. Average urinary levels in occupationally exposed subjects varied from 0.26 to 73.5 μg/L; environmental exposure urinary levels ranged from 0.16 to 7.6 μg/L. Only two studies measured temporal trends in exposure, both of which show increasing proportions of individuals with detectable levels of glyphosate in their urine over time.

CONCLUSIONS

The current review highlights the paucity of data on glyphosate levels among individuals exposed occupationally, para-occupationally, or environmentally to the herbicide. As such, it is challenging to fully understand the extent of exposure overall and in vulnerable populations such as children. We recommend further work to evaluate exposure across populations and geographic regions, apportion the exposure sources (e.g., occupational, household use, food residues), and understand temporal trends.

Environmental and health effects of the herbicide glyphosate

The herbicide glyphosate, N-(phosphonomethyl) glycine, has been used extensively in the past 40years, under the assumption that side effects were minimal. However, in recent years, concerns have increased worldwide about the potential wide ranging direct and indirect health effects of the large scale use of glyphosate. In 2015, the World Health Organization reclassified glyphosate as probably carcinogenic to humans. A detailed overview is given of the scientific literature on the movement and residues of glyphosate and its breakdown product aminomethyl phosphonic acid (AMPA) in soil and water, their toxicity to macro- and microorganisms, their effects on microbial compositions and potential indirect effects on plant, animal and human health. Although the acute toxic effects of glyphosate and AMPA on mammals are low, there are animal data raising the possibility of health effects associated with chronic, ultra-low doses related to accumulation of these compounds in the environment. Intensive glyphosate use has led to the selection of glyphosate-resistant weeds and microorganisms. Shifts in microbial compositions due to selective pressure by glyphosate may have contributed to the proliferation of plant and animal pathogens. Research on a link between glyphosate and antibiotic resistance is still scarce but we hypothesize that the selection pressure for glyphosate-resistance in bacteria could lead to shifts in microbiome composition and increases in antibiotic resistance to clinically important antimicrobial agents. We recommend interdisciplinary research on the associations between low level chronic glyphosate exposure, distortions in microbial communities, expansion of antibiotic resistance and the emergence of animal, human and plant diseases. Independent research is needed to revisit the tolerance thresholds for glyphosate residues in water, food and animal feed taking all possible health risks into account.

Morus alba leaf extract mediates neuroprotection against glyphosate-induced toxicity and biochemical alterations in the brain

Recent studies demonstrate that glyphosate exposure is associated with oxidative stress and some neurological disorders such as Parkinson's pathology. Therefore, phytochemicals, in particular phenolic compounds, have attracted increasing attention as potential agents for neuroprotection. In the present study, we investigate the impact of glyphosate on the rat brain following i.p. injection and the possible molecular target of neuroprotective activity of the phenolic fraction from Morus alba leaf extract (MALE) and its ability to reduce oxidative damage in the brain. Wistar rats from 180 to 240 g were i.p. treated with a single dose of glyphosate (100 mg kg-1 b.w.) or MALE (100 μg mL-1 kg-1 b.w.) for 2 weeks. Brain homogenates were used to evaluate neurotoxicity induced by the pesticide. For this, biochemical parameters were measured. Data shows that MALE regulated oxidative stress and counteracted glyphosate-induced deleterious effects and oxidative damage in the brain, as it abrogated LDH, protein carbonyls, and malonyldialdehyde. MALE also appears to be able to scavenge H2O2 levels, maintain iron and Ca2+ homeostasis, and increase SOD activity. Thus, in vivo results showed that mulberry leaf extract is a potent protector against glyphosate-induced toxicity, and its protective effect could result from synergism or antagonism between the various bioactive phenolic compounds in the acetonic fraction from M. alba leaf extract.

The role of L-type amino acid transporters in the uptake of glyphosate across mammalian epithelial tissues

Glyphosate is one of the most commonly used herbicides worldwide due to its broad spectrum of activity and reported low toxicity to humans. Glyphosate has an amino acid-like structure that is highly polar and shows low bioavailability following oral ingestion and low systemic toxicity following intravenous exposures. Spray applications of glyphosate in agricultural or residential settings can result in topical or inhalation exposures to the herbicide. Limited systemic exposure to glyphosate occurs following skin contact, and pulmonary exposure has also been reported to be low. The results of nasal inhalation exposures, however, have not been evaluated. To investigate the mechanisms of glyphosate absorption across epithelial tissues, the permeation of glyphosate across Caco-2 cells, a gastrointestinal epithelium model, was compared with permeation across nasal respiratory and olfactory tissues excised from cows. Saturable glyphosate uptake was seen in all three tissues, indicating the activity of epithelial transporters. The uptake was shown to be ATP and Na(+) independent, and glyphosate permeability could be significantly reduced by the inclusion of competitive amino acids or specific LAT1/LAT2 transporter inhibitors. The pattern of inhibition of glyphosate permeability across Caco-2 and nasal mucosal tissues suggests that LAT1/2 play major roles in the transport of this amino-acid-like herbicide. Enhanced uptake into the epithelial cells at barrier mucosae, including the respiratory and gastrointestinal tracts, may result in more significant local and systemic effects than predicted from glyphosate's passive permeability, and enhanced uptake by the olfactory mucosa may result in further CNS disposition, potentially increasing the risk for brain-related toxicities.