Metabolome disruption of pregnant rats and their offspring resulting from repeated exposure to a pesticide mixture representative of environmental contamination in Brittany

The use of pesticides exposes humans to numerous harmful molecules. Exposure in early-life may be responsible for adverse effects in later life. This study aimed to assess the metabolic modifications induced in pregnant rats and their offspring by a pesticide mixture representative of human exposure. Ten pregnant rats were exposed to a mixture of eight pesticides: acetochlor (246 μg/kg bw/d) + bromoxynil (12 μg/kg bw/d) + carbofuran (22.5 μg/kg bw/d) + chlormequat (35 μg/kg bw/d) + ethephon (22.5 μg/kg bw/d) + fenpropimorph (15.5 μg/kg bw/d) + glyphosate (12 μg/kg bw/d) + imidacloprid (12.5 μg/kg bw/d) representing the main environmental pesticide exposure in Brittany (France) in 2004. Another group of 10 pregnant rats served as controls. Females were fed ad libitum from early pregnancy, which is from gestational day (GD) 4 to GD 21. Urine samples were collected at GD 15. At the end of the exposure, mothers and pups were euthanized and blood, liver, and brain samples collected. 1H NMR-based metabolomics and GC-FID analyses were performed and PCA and PLS-DA used to discriminate between control and exposed groups. Metabolites for which the levels were significantly modified were then identified using the Kruskal-Wallis test, and p-values were adjusted for multiple testing correction using the False Discovery Rate. The metabolomics analysis revealed many differences between dams of the two groups, especially in the plasma, liver and brain. The modified metabolites are involved in TCA cycle, energy production and storage, lipid and carbohydrate metabolism, and amino-acid metabolism. These modifications suggest that the pesticide mixture may induce oxidative stress associated with mitochondrial dysfunction and the impairment of glucose and lipid metabolism. These observations may reflect liver dysfunction with increased relative liver weight and total lipid content. Similar findings were observed for glucose and energy metabolism in the liver of the offspring, and oxidative stress was also suggested in the brains of male offspring.

Do carbamates cause polyneuropathy?

Carbamates are reversible inhibitors of acetylcholinesterase, and some also inhibit neuropathy target esterase (NTE), the target in organophosphate-induced delayed polyneuropathy. However, based on mechanistic considerations, these carbamates were thought to be unable to initiate polyneuropathy. Consequently, clinical reports of polyneuropathy associated with carbamate exposures have been disregarded. We discuss three cases of polyneuropathy that occurred after severe poisoning by methylcarbamates. In addition, high repeated doses of phenyl N-methyl N-benzylcarbamate caused nearly 100% NTE inhibition and polyneuropathy in the hen model. These data suggest the need to reconsider the long-standing tenet that carbamates cannot cause polyneuropathy. Alternatively, a preexisting subclinical neuropathy in these individuals may have been amplified by carbamates, as observed in animal models. We suggest that individuals with underlying neuropathy (e.g., diabetics) who are poisoned by carbamates should be followed closely. In addition, procedures for the current risk assessment of carbamate pesticides may need to be reconsidered.

Carbofuran-induced oxidative stress in slow and fast skeletal muscles: prevention by memantine and atropine

Acute toxic effects of acetylcholinesterase (AChE) inhibitors on skeletal muscles are thought to involve oxidative stress with increased generation of free radicals such as reactive oxygen species (ROS) and reactive nitrogen species (RNS). Muscle hyperactivity with its increased oxygen and energy consumption appear to be the primary cause of oxidative stress. The present investigation was therefore undertaken to establish the normal levels of F(2)-isoprostanes (F(2)-IsoPs, specific markers of ROS/oxidative stress), citrulline (determinant of NO/NOS and marker of RNS), and high-energy phosphates (HEP: adenosine triphosphate, ATP and phosphocreatine, PCr) in slow (soleus) and fast (extensor digitorum longus, EDL) muscles of rats. In addition, we aimed to determine if memantine HCl (MEM), in combination with atropine sulfate (ATS), prevents carbofuran-induced changes in markers of oxidative stress. Control values were not significantly different for F(2)-IsoPs (1.142 +/- 0.027 and 1.177 +/- 0.092 ng/g) and citrulline (469.7 +/- 31.8 and 417.8 +/- 18.5 nmol/g) in soleus and EDL muscles, while the values were different for HEP (ATP, 3.66 +/- 0.11 and 5.85 +/- 0.14 micromol/g; PCr, 7.91 +/- 0.26 and 13.14 +/- 0.31 micromol/g). Rats acutely intoxicated with carbofuran (1.5 mg/kg, s.c.) showed the signs of maximal toxicity including muscle hyperactivity within 60 min of exposure. At this time, F(2)-IsoPs (177 and 153%) and citrulline (267 and 304%) levels were significantly increased, while ATP (46 and 43%) and PCr (44 and 46%) levels were decreased in soleus and EDL, respectively. Rats pretreated with MEM (18 mg/kg, s.c.) and ATS (16 mg/kg, s.c.), 60 and 15 min prior to carbofuran, respectively, showed no signs of toxicity. MEM in combination with ATS protected muscles from carbofuran-induced hyperactivity and attenuated increases in F(2)-IsoPs and citrulline, and depletion of HEP. Carbofuran-induced changes and protection by MEM and ATS were of similar magnitude in both muscles. These findings indicate that carbofuran-induced muscle hyperactivity produces oxidative stress as measured by increased ROS and RNS generation, and HEP depletion. MEM and ATS prevent the carbofuran-induced chain of events involved in oxidative stress.

Effects of furadan in the brown mussel Perna perna and in the mangrove oyster Crassostrea rhizophorae

Furadan is a carbamate pesticide used widely to combat agricultural pests. However little information is available about the toxicity of furadan in aquatic macroinvertebrates. The in vivo effects of furadan were evaluated in mussels, Perna perna, and oysters, Crassostrea rhizophorae. Glutathione S-transferase (GST), catalase (CAT) and cholinesterase (ChE) activities were measured in the gills of both species exposed to furadan (100 microg/l) for 96 h. No changes were observed in GST activity in the exposed groups. CAT activity was higher (9%) in the oysters exposed to furadan. ChE activity was inhibited by 64 and 35%, respectively, in C. rhizophorae and P. perna exposed to furadan, suggesting that the former is more susceptible to the toxic effects of furadan.

Agricultural exposure to carbamate pesticides and risk of non-Hodgkin lymphoma

Recent epidemiological studies have suggested an increased risk of non-Hodgkin lymphoma (NHL) from carbamate insecticide use among farmers. To further explore the possible relationships, we conducted a pooled analysis of three population-based case-control studies conducted in four midwestern states in the United States. A total of 985 white male subjects and 2895 control subjects were included in this analysis. Unconditional logistic regression was used to estimate the association and control for confounding. Compared with nonfarmers, farmers who had ever used carbamate pesticides had a 30% to 50% increased risk of NHL, whereas farmers without carbamate pesticide use showed no increased risk. Analyses for individual carbamate pesticides found a more consistent association with Sevin but not carbofuran, butylate, or S-ethyl dipropylthiocarbamate plus protectant. Among farmers using Sevin, the risk of NHL was limited to those who personally handled the product, those who first used the product for > or = 20 years before their disease diagnosis, and those who used the product for a longer period. These associations persisted after adjusting for other major classes of pesticides. These results suggest an increased risk of NHL associated with carbamate pesticide use, particularly Sevin. Further investigation of the association is warranted.

Carbofuran induced impairment in the hypothalamo-neurohypophyseal-gonadal complex in the teleost, Channa punctalus (Bloch)

The effect of chronic exposure to carbofuran (4.5 ppm in static water) for six months on the gonadal histophysiology and hypothalamo-neurohypophyseal complex was studied in Channa punctatus. Experimental observations revealed significant inhibition of gonadal development with associated degenerative abnormalities as evidenced by ovarian and testicular histology and reduced gonadosomatic index. Degenerative changes in ovary were exihibited by stage I (oogonium) and stage II (immature/non-vitellogenic) oocytes as marked by perinuclear ooplasmic lysis, clumping and dissolution resulting in disintigration of nuclear material altogether attributed to complete degeneration of such oocytes. Testicular deleterious changes included degeneration of spermatogenic elements and necrosis of interstitial cells of Leydig. Correlative histophysiological changes were also observed in the pituitary gonadotrophs and hypothalamic, nucleus pre-opticus, neurons that were smaller, inactive and less in number with associated necrosis. Corresponding to the changes in nucleus pre-opticus neurons, significant inhibition of brain monoamine oxidase enzyme activity was also recorded in treated group. These observations suggest that carbofuran even at low concentration level under long-term exposure is capable of inducing retardation of gonadal development which might have been mediated through the impairment of the hypothalamo-neurohypophyseal-gonadal axis in this species.

Proposal for a method for testing resistance of clothing and gloves to penetration by pesticides

The paper presents the proposal for a method for testing the resistance of materials used for the production of protective clothing and gloves to penetration by concentrated chemical preparations of pesticides. It has been based to a large extent on the recommendations of European standards, with certain modifications resulting from the specific properties of non-volatile and non-water-soluble biologically-active components of pesticides. These modifications primarily involved the use of a solid sorption medium and adjustment of research apparatus to the research conditions consistent with the proposed method. The results of preliminary studies on penetration of the selected biologically-active components of pesticides (dichlorvos, 2,4-D, cypermethrin, carbofuran) through the selected protective materials (fabric coated with viton and butyl on both sides, rubberised fabric, butyl rubber) are presented. The study confirmed the usefulness of the proposed method for testing the resistance of materials protecting against the effect of pesticides.

Effects of carbofuran on growth, biomass allocation, and intraspecific competition in Bouteloua gracilis

Growth, biomass allocation and competition between blue grama plants were examined with and without application of carbofuran, a pesticide which has been used to study insect and nematode effects on primary production. Carbofuran had no apparent effect on total plant growth, biomass allocation, or competition between neighboring plants.