Chlorpyrifos is associated with slower serum cholinesterase recovery in acute organophosphate-poisoned patients

Evaluation of toxicological effects of organophosphorus pesticide metabolites on human HepG2 cells

Trichloropyridinol (TCP); 3, 5, 6-trichloro-2-pyridinol is the primary metabolites of the organophosphorus pesticide chlorpyrifos. It is more highly persistent than parent compounds in the environment and might represent serious risks to human health. In this study, we investigated the toxicological effects and mechanism of TCP on HepG2 cells. The results revealed that TCP induced DNA damage and apoptosis on HepG2 cells. Besides, up-regulating the expression level of Bax /Bcl-2, a reduction in mitochondrial membrane potential, caspase-9/-3 activation and the release of cytochrome-c are contributed to the toxicological effects of TCP on HepG2 cells. These data indicated that the cytotoxic effects of TCP might be associated with the activity of mitochondrial apoptotic pathways. In conclusion, the results demonstrated that TCP poses a potential threat to human health by inducing toxicological effects in the liver.

Case Fatality as an Indicator for the Human Toxicity of Pesticides-A Systematic Scoping Review on the Availability and Variability of Severity Indicators of Pesticide Poisoning

Objective: To investigate if case fatality and other indicators of the severity of human pesticide poisonings can be used to prioritize pesticides of public health concern. To study the heterogeneity of data across countries, cause of poisonings, and treatment facilities. Methods: We searched literature databases as well as the internet for studies on case-fatality and severity scores of pesticide poisoning. Studies published between 1990 and 2014 providing information on active ingredients in pesticides or chemical groups of active ingredients were included. The variability of case-fatality-ratios was analyzed by computing the coefficient of variation as the ratio of the standard deviation to the mean. Findings: A total of 149 papers were identified of which 67 could be included after assessment. Case-fatality-ratio (CFR) on 66 active ingredients and additionally on 13 groups of active ingredients were reported from 20 countries. The overall median CFR for group of pesticides was 9%, for single pesticides 8%. Of those 12 active ingredients with a CFR above 20% more than half are WHO-classified as “moderately hazardous” or “unlikely to present acute hazard”. Two of seven pesticides considered “unlikely to present hazard in normal use” showed a CFR above 20%. The cross-study variability of reported case fatality was rather low. Studies most often utilized the Glasgow Coma Score for grading the severity of poisoning. Conclusion: Although human pesticide poisoning is a serious public health problem, an unexpectedly small number of publications report on the clinical outcomes within our study period. However, CFRs of acute human pesticide poisoning are available for several groups of pesticides as well as for active ingredients showing moderate cross-study variability. Our results underline that CFR is an indicator of the human toxicity of pesticides and can be utilized to prioritize highly hazardous pesticides especially since there is limited correspondence between the animal-test-based hazard classification and the human CFR of the respective pesticide. The reporting of available poisoning data should be improved, human case-fatality data are a reasonable tool to be included systematically in the periodic statutory review of pesticides and their regulation.

Effects of chlorpyrifos and trichloropyridinol on HEK 293 human embryonic kidney cells

Chlorpyrifos (CPF) [O, O-diethyl -O-3, 5, 6-trichloro-2-pyridyl phosphorothioate] is an organophosphate insecticide widely used for agricultural and urban pest control. Trichloropyridinol (TCP; 3,5,6-trichloro-2-pyridinol), the primary metabolite of CPF, is often used as a generic biomarker of exposure for CPF and related compounds. Human embryonic kidney 293 (HEK 293) cells were exposed to CPF and TCP with varying concentrations and exposure periods. Cell cultures enable the cost-effective study of specific biomarkers to help determine toxicity pathways to predict the effects of chemical exposures without relying on whole animals. Both CPF and TCP were found to induce cytotoxic effects with CPF being more toxic than TCP with EC₅₀ values of 68.82 μg/mL and 146.87 μg·ml^-1 respectively. Cell flow cytometric analyses revealed that exposure to either CPF or TCP leads to an initial burst of apoptotic induction followed by a slow recruitment of cells leading towards further apoptosis. CPF produced a strong induction of IL6, while TCP exposure resulted in a strong induction of IL1α. Importantly, the concentrations of CPF and TCP required for these cytokine inductions were higher than those required to induce apoptosis. These data suggest CPF and TCP are cytotoxic to HEK 293 cells but that the mechanism may not be related to an inflammatory response. CPF and TCP also varied in their effects on the HEK 293 proteome with 5 unique proteins detected after exposure to CPF and 31 unique proteins after TCP exposure.

Variable response of cholinesterase activities following human exposure to different types of organophosphates

We investigated the red blood cell (RBC) acetylcholinesterase (AChE) activities and butyrylcholinesterase (BChE) activities at presentation to the emergency department (ED) and at 24 h after presentation following poisoning by dichlorvos, fenitrothion, or ethyl p-nitrophenol thio-benzene phosphonate (EPN). Although the patients from different groups had similar characteristics at presentation such as time interval from ingestion to presentation to the ED and the amount of organophosphate ingested, the dichlorvos group had significantly lower BChE levels than the fenitrothion group and lower RBC cholinesterase activity than the EPN group. Patients poisoned with EPN or dichlorvos had significantly higher inhibition of BChE activities from baseline than RBC AChE activities at presentation. Twenty four hours after administration of pralidoxime, RBC AChE activities had increased in patients in the dichlorvos and EPN groups, while RBC AChE activities had slightly decreased in the fenitrothion group. BChE activities increased significantly in the dichlorvos group but decreased in the EPN group. The recovery patterns of RBC AChE and BChE activities did not match in any particular individual. This study showed that the patterns of inhibition and recovery of the activities of two cholinesterases after treatment are highly variable according to the organophosphate and in different individuals.

Severe oral and intravenous insecticide mixture poisoning with diabetic ketoacidosis: a case report

Background

The widespread use of pesticides in public health protection and agricultural pest control has caused severe environmental pollution and health hazards, especially in developing countries, including cases of severe acute and chronic human poisoning. Diabetic ketoacidosis is an uncommon manifestation of acute pesticide poisoning. Suicidal pesticide poisoning by injection is also an unusual way to take poison. We report a severe pesticide mixture poisoning case with diabetic ketoacidosis in an adult with improved outcome after supportive treatment and large doses of atropine.

Case presentation

A 30-year-old unmarried Moroccan Arab male with a previous history of active polysubstance abuse and behavior disorders had ingested and self injected intravenously into his forearm an unknown amount of a mixture of chlorpyrifos and cypermethrin. He developed muscarinic and nicotinic symptoms with hypothermia, inflammation in the site of the pesticide injection without necrosis. Red blood cell cholinesterase and plasma cholinesterase were very low (<10%). By day 3, the patient developed stroke with hypotension (80/50 mmHg) and tachycardia (143 pulses /min). Laboratory tests showed severe hyperglycemia (4.49 g/dL), hypokaliemia (2.4 mEq/L), glycosuria, ketonuria and low bicarbonate levels (12 mEq/L) with improvement after intensive medical treatment and treatment by atropine.

Conclusion

Suicidal poisonings with self-injection of insecticide were rarely reported but could be associated with severe local and systemic complications. The oxidative stress caused by pyrethroids and organophosphates poisoning could explain the occurrence of hyperglycemia and ketoacidosis.