Atrazine in plasma and tissue following atrazine-aminotriazole-ethylene glycol-formaldehyde poisoning

Atrazine exposure promotes cardiomyocyte pyroptosis to exacerbate cardiotoxicity by activating NF-κB pathway

Atrazine is a ubiquitous herbicide with persistent environmental presence and accumulation in the food chain, posing potential health hazards to organisms. Increasing evidence suggests that atrazine may have detrimental effects on various organ systems, including the nervous, digestive, and immune systems. However, the specific toxicity and underlying mechanism of atrazine-induced cardiac injury remain obscure. In this study, 4-week-old male C57BL/6 mice were administered atrazine via intragastric administration at doses of 50 and 200 mg/kg for 4 and 8 weeks, respectively. Our findings showed that atrazine exposure led to cardiac fibrosis, as evidenced by elevated heart index and histopathological scores, extensive myofiber damage, and interstitial collagen deposition. Moreover, atrazine induced cardiomyocyte apoptosis, macrophage infiltration, and excessive production of inflammatory factors. Importantly, atrazine upregulated the expressions of crucial pyroptosis proteins, including NLRP3, ASC, CASPASE1, and GSDMD, via the activation of NF-κB pathway, thus promoting cardiomyocyte pyroptosis. Collectively, our findings provide novel evidence demonstrating that atrazine may exacerbate myocardial fibrosis by inducing cardiomyocyte pyroptosis, highlighting its potential role in the development of cardiac fibrosis.

Atrazine-induced changes in the myocardial structure of peripubertal rats

The aim of the present study was to investigate the effect of atrazine (6-chloro-N(2)-ethyl-N(4)-isopropyl-1,3,5-triazine-2,4-diamine) on the left ventricle myocardium in juvenile/peripubertal male Wistar rats. Atrazine was administered orally at 50 or 200 mg/kg of body weight dose for 28 consecutive days. In order to assess possible structural alterations, tissue sections were examined histologically and then subjected to quantification analysis using stereological methods. The tissue specimens were routinely processed and stained with Mallory trichrome method in order to clearly distinguish muscle cells from the connective tissue components. A toluidine blue staining method was additionally used for the demonstration of mast cells. Statistically significant increase in length density and numerical density of capillaries were found at both the investigated doses of atrazine compared with the control. The increase in surface density and volume density of capillaries found at lower dosage of atrazine was significant in comparison with the control. The extensive mast cell degranulation was noted on the histological examination at both doses of the applied chemical. No significant changes were demonstrated for the stereological parameters of cardiomyocytes. Based on the available published data and the present results, it can be concluded that atrazine promoted angiogenesis in the rat myocardium, which might be partially mediated by mast cells.

A physiologically based pharmacokinetic model for atrazine and its main metabolites in the adult male C57BL/6 mouse

Atrazine (ATR) is a chlorotriazine herbicide that is widely used and relatively persistent in the environment. In laboratory rodents, excessive exposure to ATR is detrimental to the reproductive, immune, and nervous systems. To better understand the toxicokinetics of ATR and to fill the need for a mouse model, a physiologically based pharmacokinetic (PBPK) model for ATR and its main chlorotriazine metabolites (Cl-TRIs) desethyl atrazine (DE), desisopropyl atrazine (DIP), and didealkyl atrazine (DACT) was developed for the adult male C57BL/6 mouse. Taking advantage of all relevant and recently made available mouse-specific data, a flow-limited PBPK model was constructed. The ATR and DACT sub-models included blood, brain, liver, kidney, richly and slowly perfused tissue compartments, as well as plasma protein binding and red blood cell binding, whereas the DE and DIP sub-models were constructed as simple five-compartment models. The model adequately simulated plasma levels of ATR and Cl-TRIs and urinary dosimetry of Cl-TRIs at four single oral dose levels (250, 125, 25, and 5mg/kg). Additionally, the model adequately described the dose dependency of brain and liver ATR and DACT concentrations. Cumulative urinary DACT amounts were accurately predicted across a wide dose range, suggesting the model's potential use for extrapolation to human exposures by performing reverse dosimetry. The model was validated using previously reported data for plasma ATR and DACT in mice and rats. Overall, besides being the first mouse PBPK model for ATR and its Cl-TRIs, this model, by analogy, provides insights into tissue dosimetry for rats. The model could be used in tissue dosimetry prediction and as an aid in the exposure assessment to this widely used herbicide.

Metabolic acidosis in prometryn (triazine herbicide) self-poisoning

INTRODUCTION

Prometryn is a triazine herbicide, which is one of the most extensively used groups of herbicides. The mechanism of acute triazine herbicide toxicity in humans is not known. We report a first case of acute prometryn poisoning.

CASE REPORT

A 62-year-old male ingested 50 g of prometryn and ethanol in a suicide attempt. On arrival two hours after ingestion, he was somnolent and vomited. Seven hours after ingestion laboratory tests showed metabolic acidosis with a calculated anion gap of 47.5 mmol/L and lactate of 23.4 mmol/L. Gas chromatography/mass spectrometry revealed serum prometryn concentrations of 48.1 mg/L. Hemodialysis corrected metabolic acidosis, but the serum prometryn concentration increased to 67.7 mg/L. The lactate level after hemodialysis was 11.7 mmol/L and returned within normal limits 47 hours after ingestion. The patient was discharged without any sequelae after psychiatric evaluation.

CONCLUSION

In high anion gap metabolic acidosis we should consider poisoning with prometryn and other triazine herbicides. Hemodialysis corrects metabolic derangements, but it does not lower serum prometryn concentration.

Cancer Incidence Among Pesticide Applicators Exposed to Atrazine in the Agricultural Health Study

BACKGROUND

Atrazine is the most heavily applied agricultural pesticide for crop production in the United States. Both animal and human studies have suggested that atrazine is possibly carcinogenic, but results have been mixed. We evaluated cancer incidence in atrazine-exposed pesticide applicators among 53,943 participants in the Agricultural Health Study, a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina.

METHODS

We obtained detailed pesticide exposure information using a self-administered questionnaire completed at the time of enrollment (1993-1997). Cancer incidence was followed through December 31, 2001. We used adjusted Poisson regression to calculate rate ratios (RRs) and 95% confidence intervals (CIs) of multiple types of cancer among atrazine exposed applicators. P(trend) values were calculated using atrazine exposure as a continuous variable, and all statistical tests were two-sided. Two exposure metrics were used: quartiles of lifetime days of exposure and quartiles of intensity-weighted lifetime days of exposure.

RESULTS

36,513 (68%) applicators reported ever using atrazine; exposure was not associated with overall cancer incidence. Comparisons of cancer incidence in applicators with the highest atrazine exposure and those with the lowest exposure, assessed by lifetime days (RR(LD)) and intensity-weighted lifetime days (RR(IWLD)) of exposure yielded the following results: prostate cancer, RR(LD) = 0.88, 95% CI = 0.63 to 1.23, P(trend) =.26, and RR(IWLD) = 0.89, 95% CI = 0.63 to 1.25, P(trend) =.35; lung cancer, RR(LD) = 1.91, 95% CI = 0.93 to 3.94, P(trend) =.08, and RR(IWLD) = 1.37, 95% CI = 0.65 to 2.86, P(trend) =.19; bladder cancer, RR(LD) = 3.06, 95% CI = 0.86 to 10.81, P(trend) =.18, and RR(IWLD) = 0.85, 95% CI = 0.24 to 2.94, P(trend) =.71; non-Hodgkin lymphoma, RR(LD) = 1.61, 95% CI = 0.62 to 4.16, P(trend) =.35, and RR(IWLD) = 1.75, 95% CI = 0.73 to 4.20, P(trend) =.14; and multiple myeloma, RR(LD) = 1.60, 95% CI = 0.37 to 7.01, P(trend) =.41, and RR(IWLD) = 2.17, 95% CI = 0.45 to 10.32, P(trend) =.21.

CONCLUSIONS

Our analyses did not find any clear associations between atrazine exposure and any cancer analyzed. However, further studies are warranted for tumor types in which there was a suggestion of trend (lung, bladder, non-Hodgkin lymphoma, and multiple myeloma).

Ethylene Glycol Dimethacrylate Cross-linking Anion Exchange Resin as Phosphate Binder: Effects on Rat gut and Digestion by Small Intestine Contents

In the present study, ethylene glycol dimethacrylate cross-linking 4-vinylpyridinium anion exchange resin (EGDMA-4VP) effectively bound dietary phosphate in normal rats. However, EGDMA-4VP induced more adverse effects in rat gut than cellulose or Dowex 1X2 (both of which have higher water content), and caused damage to the intestine. In order to resolve this seeming paradox, digestion of EGDMA-4VP with rat small intestine content (S-9 fraction) and carboxyl esterase was investigated in vitro to examine the stability of the resin under conditions it would be subjected to as an orally administered medicine. EGDMA-4VP was digested by small intestinal enzymes, with the exception of carboxyl esterase, and the degradation product ethylene glycol (EG) caused reversible relaxation of longitudinal muscle (but not circular muscle) in rat small intestine. Degradation products increased uptake of3H2O into primary cultured rat small intestinal muscle cells, but the increase was not significant.

Effects of selected herbicides on cytokine production in vitro

To evaluate possible deleterious effects of commonly used herbicides on leukocytes, cytokine production was selected as a sensitive indicator. After in vitro exposure of human peripheral blood mononuclear cells from normal donors, the production of all 3 cytokines tested--interferon-gamma (a type 1 cytokine), interleukin-5 (a type 2 cytokine) and tumor necrosis factor-alpha (an inflammatory cytokine)--was impaired by up to 70, 50 and 70% respectively in a concentration-dependent manner in cultures exposed to atrazine (0.03-3 microM in 1% dimethylsulfoxide, DMSO). The effect paralleled that seen with dexamethasone, a known immunosuppressive agent. Other pesticides also dissolved in DMSO--mecoprop, simazine or MCPA (each up to 1 microM)--or dissolved in phosphate-buffered saline--diuron (up to 1 microM), isoproturon (up to 3 microM), metoxuron (up to 8 microM) or metamitron (up to 80 microM)--showed no concentration-related effects on cytokine production. There was, however, an inhibition of IFN-gamma and TNF-alpha production by simazine, metoxuron and mecoprop and of all three cytokines tested by diuron. MCPA (0.01 and 0.1 microM) stimulated the production of TNF-alpha. Thus, exposure to herbicides leading to plasma levels in the micromolar range induces imbalance in cytokine production.

Biological Monitoring of Pesticide Exposure: a review. Introduction

Pesticides are used worldwide in agriculture, industry, public health and for domestic applications: as a consequence, a great part of the population may be exposed to these compounds. In spite of this extensive use, knowledge on the health risks associated with prolonged exposure is rather poor, and major uncertainties still exist. Epidemiological observations in man have so far produced little conclusive information, mainly because of weaknesses in exposure assessment. Therefore, information on the type and levels of exposure is fundamental in order to better understand and characterize risk to human health. Exposure assessment can be carried out via measurement of environmental concentrations, as well as via determination of the chemical or its metabolites in body tissues (biological monitoring). Besides indices of internal dose, biological monitoring also includes measurements of early effects attributable to interaction between the chemical agent and the human body. Biological monitoring has the advantage, over environmental monitoring, of determining the dose actually absorbed via any possible route: differences in absorption can be taken into account. whether they are due to biological variability or to use of protective equipment. When, in some cases, a combination of occupational and non-occupational exposure occurs, this also can be taken into consideration by biological monitoring. Few reference documents have been published on biological monitoring of pesticides. For this reason, the Office of Occupational Health of the World Health Organization gave ICPS a mandate to prepare a monograph specifically addressed to reviewing methods for biological monitoring of pesticide exposure. This review is based on more than 300 studies published over the period 1980-1999. For the most representative chemical classes, the available biological exposure indices are reported. Both indices of internal dose and. when available, of early effects are discussed. The reported tests were used to monitor exposure of pesticide applicators in agriculture and public health, manufacturing and formulating workers. subjects poisoned after accidental exposure or attempted suicide, volunteers involved in pharmacokinetic studies, as well as sub-groups of the general population exposed to environmentally persistent pesticides. Single chapters deal with organophosphorus insecticides, carbamate pesticides, dithiocarbamates, phenoxyacids, quaternary ammonium compounds. coumarin rodenticides, synthetic pyrethroids, organochlorine pesticides, chlorotriazines, and pentachlorophenol.

Biodegradation of s-triazine compounds by a stable mixed bacterial community

The potential for biodegradation of s-triazine pesticides was investigated in laboratory batch and sequence batch experiments using a stable mixed bacterial community enriched on atrazine. The experiments were performed aerobically in a mineral salt solution complemented with a mixture of s-triazines as sole carbon and energy sources. Comparisons were made between the efficiency of the inoculum for atrazine degradation in mineral salt solution and in wastewater. In batch cultivation, atrazine, simazine, hydroxyatrazine, and terbutylazine were degraded to concentrations below 0.1 mg/liter after 6 days; evidence of the mineralization was the detection of 14CO2 from [U-ring-14C] atrazine and the production of nitrate and chloride ions. The low degradation rate observed for cyanuric acid and desethylatrazine suggests that degradation proceeded via N-dealkylation and dechlorination. Nevertheless, degradation of ametryne and cyromazine presume the involvement of other degradation pathways. Evidence was given that presence of other additional carbon sources is not an obstacle to atrazine biodegradation, since better results were obtained using wastewater.

Herbicide: fatal ammonium thiocyanate and aminotriazole poisoning

OBJECTIVE

To describe fatal herbicide poisoning with Radoxone TL composed of aminotriazole and ammonium thiocyanate.

CASE REPORT

A 54-year-old man was hospitalized because of unexplained coma with myoclonic jerks and vascular collapse. Despite symptomatic treatment with mechanical ventilation and vascular filling, life-threatening shock occurred with oliguria, profound metabolic acidosis and cardiac arrest. Hyperchloremia (141 mmol/L) with reversed anion gap (-19) suggested interference with chloride measurement caused by halogens (Br,F,I) or other anions such as thiocyanate. Eventually a weed killer, Radoxone TL containing ammonium thiocyanate, was found at the patient's house. Thiocyanate and aminotriazole blood levels were 750 mg/L and 138 mg/L respectively more than 12 hours after ingestion. After prolonged cardiopulmonary resuscitation, continuous venovenous hemodiafiltration was performed. Despite hemodynamic recovery the patient died 48 hours later of postanoxic coma.

CONCLUSION

Aminotriazole, a systemic nonselective herbicide, is often associated with ammonium thiocyanate which enhances its activity. Experimental studies and previous fatal cases suggest a predominant toxicity of thiocyanate. Early diagnosis is important.

Epidemiology of atrazine

Chronically exposed workers in chemical plants have revealed no increased incidence of benign or malignant disease attributable to atrazine. Some case-control studies showed a slight increase of non-Hodgkin's lymphoma (NHL) incidence while others were negative. Weighted evidence supports no causal association of malignant changes in farming populations with atrazine. Two studies on a rural population suggested an increase of ovarian tumors in exposed women. Neither statistics nor exposure data are satisfactory, however, and no other studies present supporting evidence. New studies under clearly defined conditions are desirable. Very high doses of atrazine ingested in suicidal attempts had no acute clinical effect, suggesting that atrazine is virtually innocuous to humans. Sporadic reports on suspected acute poisoning leave too many questions open to be convincing: they reflect coincidence rather than causality. The tolerance of ruminants to triazine is limited. Severe poisoning in case of accidental intake of concentrated products is to be expected. Poisoning through ingestion has been controlled with activated charcoal. Adsorption on fodder enhances tolerability of triazines. Suspected poisoning through spray-contaminated fodder requires differential diagnosis to avoid confusion with other pasture toxins, electrolyte problems, or gastrointestinal infection.