Guillain-Barre syndrome due to organophosphate compound poison

Acute manifestations of Organophosphate Compound (OPC) poison are due to effect cholinergic excess. Others are intermediate syndrome [IMS], organophosphate induced delayed neuropathy [OPIND] and chronic organophosphate induced neuropsychiatric disorder [COPIND]. All these manifestation have specific period of occurrence and duration. There are very sparse reports of toxic demylination due to OPC poisoning. We report a case of Guillain-Barre Syndrome (GBS) due to toxic demyelination following OPC poison.

Intermediate Syndrome after Organophosphate Intoxication in Patient with End-Stage Renal Disease

A 42-year-old woman with a 24-year history of systemic lupus erythematous and lupus nephritis for 8 years who had been receiving regular hemodialysis for 4 years for nonoligoric end-stage renal disease (ESRD) ingested about 100 mL of 40.8% chlorpyrifos in a suicide attempt. On admission to our emergency department, she was drowsy. Gastric lavage, activated charcoal, pralidoxime (PAM), and atropine were administered 4 h later. Her consciousness level improved gradually with treatment, which included hemodialysis. However, on the second hospital day, intermittent fever to 38.4 degrees C, sore throat, and trismus were noted. About 45 h after chlorpyrifos ingestion, the patient developed profound motor paralysis followed by respiratory arrest, consistent with the diagnosis of intermediate syndrome (IMS), even with adequate atropine and PAM. Chorealike involuntary movements of her upper limbs were noticed on the fifth day. Intermittent tonic-clonic seizures, each attack lasting for 3 to 5 min, appeared on the 13th day, which responded well to intravenous diazepam and phenytoin. She was discharged on the 18th day. This case suggests that patients with ESRD suffering chlorpyrifos intoxication are at risk of IMS. Prompt endotracheal intubation, intensive care, and hemodialysis are necessary for life support.

Extreme variability in the formation of chlorpyrifos oxon (CPO) in patients poisoned by chlorpyrifos (CPF)

Chlorpyrifos (CPF) is a pesticide that causes tens of thousands of deaths per year worldwide. Chlorpyrifos oxon (CPO) is the active metabolite of CPF that inhibits acetylcholinesterase. However, this presumed metabolite has escaped detection in human samples by conventional methods (HPLC, GC-MS, LC-MS) until now. A recently developed enzyme-based assay allowed the determination of CPO in the nanomolar range and was successfully employed to detect this metabolite. CPO and CPF were analysed in consecutive plasma samples of 74 patients with intentional CPF poisoning. A wide concentration range of CPO and CPF was observed and the ratio of CPO/CPF varied considerably between individuals and over time. The ratio increased during the course of poisoning from a mean of 0.005 in the first few hours after ingestion up to an apparent steady-state mean of 0.03 between 30 and 72 h. There was a hundred-fold variation in the ratio between samples and the interquartile range (between individuals) indicated over half the samples had a 5-fold or greater variation from the mean. The ratio was independent of the CPF concentration and the pralidoxime regimen. CPO was present in sufficient quantities to explain any observed acetylcholinesterase inhibitory activity. The effectiveness of pralidoxime in reactivating the inhibited acetylcholinesterase is strongly dependent on the CPO concentration. Differences in clinical outcomes and the response to antidotes in patients with acute poisoning may occur due to inter-individual variability in metabolism.

Combined effects of atrazine and chlorpyrifos on susceptibility of the tiger salamander to Ambystoma tigrinum virus

Several hypotheses have been examined as potential causes of global amphibian declines, including emerging infectious diseases and environmental contaminants. Although these factors are typically studied separately, animals are generally exposed to both stressors simultaneously. We examined the effects of the herbicide atrazine and the insecticide chlorpyrifos on the susceptibility of tiger salamander larvae, Ambystoma tigrinum, to a viral pathogen, Ambystoma tigrinum virus (ATV). Environmentally relevant concentrations of atrazine (0, 20, 200 microg/L) and chlorpyrifos (0, 2, 20, 200 microg/L) were used along with ATV in a fully factorial experimental design whereby individually housed, 4-week-old larvae were exposed for 2 weeks. Atrazine alone was not lethal to larvae, and chlorpyrifos alone was lethal only at the highest concentration. When combined with ATV, chlorpyrifos increased susceptibility to viral infection and resulted in increased larval mortality. A significant interactive effect between atrazine and ATV was detected. Atrazine treatments slightly decreased survival in virus-exposed treatments, yet slightly increased survival in the virus-free treatments. These findings corroborate earlier research on the impacts of atrazine, in particular, on disease susceptibility, but exhibit greater effects (i.e., reduced survival) when younger larvae were examined. This study is the first of its kind to demonstrate decreases in amphibian survival with the combination of pesticide and a viral disease. Further examination of these multiple stressors can provide key insights into potential significance of environmental cofactors, such as pesticides, in disease dynamics.

Predicting outcome using butyrylcholinesterase activity in organophosphorus pesticide self-poisoning

BACKGROUND

The usefulness of a low butyrylcholinesterase (BuChE) activity on admission for predicting severity in acute organophosphorus (OP) insecticide poisoning has long been debated. Previous studies have been confounded by the inclusion of multiple insecticides with differing inhibitory kinetics.

AIM

We aimed to assess the usefulness of admission BuChE activity, together with plasma OP concentration, for predicting death with two specific organophosphorus insecticides.

DESIGN

A prospective cohort of self-poisoned patients.

METHODS

We prospectively studied 91 and 208 patients with proven dimethoate or chlorpyrifos self-poisoning treated using a standard protocol. Plasma butyrylcholinesterase activity and OP concentration were measured on admission and clinical outcomes recorded.

RESULTS

The usefulness of a plasma BuChE activity <600 mU/ml on admission varied markedly--while highly sensitive in chlorpyrifos poisoning (sensitivity 11/11 deaths; 100%, 95% CI 71.5-100), its specificity was only 17.7% (12.6-23.7). In contrast, while poorly sensitive for deaths in dimethoate poisoning [12/25 patients; 48%, (27.9-68.7)] it was reasonably specific [86.4% (75.7-93.6)]. A high OP concentration on admission was associated with worse outcome; however, a clear threshold concentration was only present for dimethoate poisoning.

CONCLUSION

Plasma BuChE activity on admission can provide useful information; however, it must be interpreted carefully. It can only be used to predict death when the insecticide ingested is known and its sensitivity and specificity for that insecticide has been studied. Plasma concentration of some OP insecticides predicts outcome. The development of rapid bedside tests for OP detection may aid early assessment of severity.

Acute chlorpyrifos poisoning in pregnancy: a case report

BACKGROUND

Pesticide exposures and poisoning are common and generally under-reported in poorly resourced countries where women are mainly involved in agricultural work. Cases of organophosphate poisoning in pregnancy are unusual.

CASE REPORT

A 22-year-old woman in her 29th week of pregnancy presented to King Edward VIII Hospital, Durban, South Africa having had multiple generalized tonic-clonic seizures at home. An initial presumptive diagnosis of eclampsia was made and treatment using intravenous MgSO(4) was initiated. Signs of OP toxicity included a garlic odor; vomiting, diarrhea, fecal incontinence; hypersecretions with airway compromise, diffuse rhonchi; pinpoint pupils; and muscle weakness and fasciculations. The patient responded to intravenous doses of atropine; oximes were not available. Although the mother survived, the infant was born prematurely and died two days after birth without showing any OP signs.

CONCLUSIONS

Organophosphate poisoning may mimic acute complications in pregnancy, such as eclampsia and seizures. Immediate management includes general supportive measures and use of specific pharmacological agents such as atropine and oximes. Poisoning during pregnancy may result in serious adverse effects for both mother and the fetus or neonate. Prompt diagnosis and treatment are necessary to avoid adverse outcomes.

EVALUATION OF SUBCHRONIC CHLORPYRIFOS POISONING ON HEMATOLOGICAL AND SERUM BIOCHEMICAL CHANGES IN MICE AND PROTECTIVE EFFECT OF VITAMIN C

Chlorpyrifos (CPF) is one of the most widely used organophosphorous insecticides in agriculture with its attendant adverse health outcomes. This study aimed at evaluating the effect of subchronic oral CPF administration on hematological and serum biochemical indices, and the possible ameliorating effect of vitamin C on the indices in mice. Thirty mice divided into 3 groups of 10 mice each were used for this study. Mice in group I (control) were dosed with vegetable oil, while those in group II were given CPF (21.3 mg/kg~ 1/5(th) LD(50)) only. Mice in group III were pretreated with vitamin C (100 mg/kg) prior to dosing with CPF 30 min later (Vitamin C + CPF-treated group). This regime was given to each group of mice three times a week for a period of ten weeks. During the study period, mice were examined for signs of toxicity, and weight of each mouse was measured every week. At the end of the study period, blood samples were collected from the mice and analyzed for packed cell volume (PCV), total red blood cell (RBC), white blood cell (WBC) and total protein (TP). Serum obtained from the blood was analyzed for Na( +, K+ and Cl-), urea, creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP). The results showed that mice in the vitamin C + CPF-treated group exhibited milder signs of toxicity and significant increase in weight gain (p<0.01) compared to the CPF-treated group. No significant increase in weight in the CPF-treated group was observed compared to the control. There was a significant increase in PCV, RBC, Hb, TP and creatinine, but a significant decrease was obtained in WBC, ALT and AST in the CPF-treated group compared to the control. All the parameters with the exception of WBC, ALT and AST (which increased significantly), were significantly decreased in the vitamin C + CPF-treated group compared to CPF-treated group. ALP was significantly elevated in the CPF-treated group compared to both the control and vitamin C + CPF-treated group. No significant changes in urea and the measured electrolytes in all three groups, except a significant decrease in the concentration of Na(+) was observed in the CPF-treated group compared to the control. The study demonstrated that pretreatment of CPF-administered mice with vitamin C significantly altered some important hematological and serum biochemical parameters, revealing the protective action of the vitamin against some organ damage induced by CPF.

Scopolamine treatment for severe extra-pyramidal signs following organophosphate (chlorpyrifos) ingestion

BACKGROUND

The use of competitive inhibitors of acetylcholine other than atropine, for patients with organophosphate poisoning is controversial. Because scopolamine ability to cross the blood-brain barrier is better than that of atropine, it has been suggested that it should be used in patients with organophosphate poisoning who have central nervous system manifestations.

CASE DESCRIPTION

A 17-year-old girl was admitted to the pediatric ward after ingesting chlorpyrifos as a suicidal attempt. She reported vomiting three times. She had no other symptoms for 12 hours and then over the course of 36 hours gradually developed extrapyramidal signs and became comatose. She was treated with intravenous scopolamine. Within 3 minutes the patient started to respond to verbal commands and answered simple questions rigidity subsided, and she was able to sit in bed. She was discharged after 4 days with no neurological sequelae.

CONCLUSIONS

We suggest, that in patients with organophosphate poisoning who have mainly central nervous system toxicity scopolamine administration might be considered.

A case study of acute human chlorpyrifos poisoning: Novel aspects on metabolism and toxicokinetics derived from liquid chromatography–tandem mass spectrometry analysis of urine samples

The metabolic fate of the organophosphorothioate-type insecticide chlorpyrifos (CP) in an acutely intoxicated 59 years old female was investigated by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) analysis of urine samples. Fifteen metabolites of CP and its bioactivated intermediate chlorpyrifos-oxon (CPO), respectively, of which only three have been described in man so far, were identified on the basis of characteristic MS/MS transitions, precursor/product ion and/or neutral loss scans, chlorine isotopomer patterns, and partly by synthesis of reference compounds and subsequent structure confirmation. Three distinct biotransformation routes of CP are proposed: (1) cleavage reactions at the aromatic phosphoester bond, (2) cleavage reactions at the alkyl phosphoester bonds, and (3) glutathione (GSH) dependent nucleophilic substitution of the 6-chlorine at the aromatic moiety. Route (2) has not been reported in humans before and (3) is a hitherto completely unknown scheme of CP metabolism. Urinary markers of the latter were chiefly cysteine S-conjugates of mono-dechlorinated CP, CPO, mono-O-deethyl CP, and mono-O-deethyl CPO as well as the 6-mercapturic acid conjugate of 3,5-dichloro-2-pyridinol. The presence of 3,5-dichloro-6-methylthio-2-pyridinol as well as its O-glucuronide suggests further a cysteine S-conjugate beta-lyase mediated degradation. In addition to the qualitative LC-MS/MS screening the renal elimination profiles of the primary products of scheme (1), i.e. diethyl thiophosphate (DETP), diethyl phosphate (DEP), and 3,5,6-trichloro-2-pyridinol (TCP), were monitored over 14 days (n=21). A biphasic first-order excretion mechanism with half-lives of 21.5h (initial fast excretion phase) and 119.5h (terminal phase) for the sum of free DETP and DEP was found. TCP was hardly eliminated in its free form (O-glucuronide identified as phase II conjugate) and half-lives calculated for the total amount of TCP (acidic hydrolysis of urine samples) were 40.8 and 150.7h. The present study gives a more detailed view on the biotransformation of CP and together with the obtained kinetic data adds novel aspects to the limited knowledge of human metabolism of this xenobiotic, in particular at high dosage.

Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study

BACKGROUND

Although more than 100 organophosphorus insecticides exist, organophosphorus poisoning is usually regarded as a single entity, distinguished only by the compound's lethal dose in animals. We aimed to determine whether the three most common organophosphorus insecticides used for self-poisoning in Sri Lanka differ in the clinical features and severity of poisoning they cause.

METHODS

We prospectively studied 802 patients with chlorpyrifos, dimethoate, or fenthion self-poisoning admitted to three hospitals. Blood cholinesterase activity and insecticide concentration were measured to determine the compound and the patients' response to insecticide and therapy. We recorded clinical outcomes for each patient.

FINDINGS

Compared with chlorpyrifos (35 of 439, 8.0%), the proportion dying was significantly higher with dimethoate (61 of 264, 23.1%, odds ratio [OR] 3.5, 95% CI 2.2-5.4) or fenthion (16 of 99, 16.2%, OR 2.2, 1.2-4.2), as was the proportion requiring endotracheal intubation (66 of 439 for chlorpyrifos, 15.0%; 93 of 264 for dimethoate, 35.2%, OR 3.1, 2.1-4.4; 31 of 99 for fenthion, 31.3%, 2.6, 1.6-4.2). Dimethoate-poisoned patients died sooner than those ingesting other pesticides and often from hypotensive shock. Fenthion poisoning initially caused few symptoms but many patients subsequently required intubation. Acetylcholinesterase inhibited by fenthion or dimethoate responded poorly to pralidoxime treatment compared with chlorpyrifos-inhibited acetylcholinesterase.

INTERPRETATION

Organophosphorus insecticide poisoning is not a single entity, with substantial variability in clinical course, response to oximes, and outcome. Animal toxicity does not predict human toxicity since, although chlorpyrifos is generally the most toxic in rats, it is least toxic in people. Each organophosphorus insecticide should be considered as an individual poison and, consequently, patients might benefit from management protocols developed for particular organophosphorus insecticides.

Determination of chlorpyrifos metabolites in human urine by reversed-phase/weak anion exchange liquid chromatography–electrospray ionisation–tandem mass spectrometry

A liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) method for the quantification of major chlorpyrifos (CP) metabolites, i.e. diethyl thiophosphate (DETP), diethyl phosphate (DEP), and 3,5,6-trichloro-2-pyridinol (TCP), in human urine was developed. Simultaneous separation of the parent compound and its primary biotransformation products was achieved within 20 min in gradient elution mode employing a mixed-mode reversed-phase/weak anion exchange (RP/WAX) separation principle. The analytical method was developed for a toxicokinetic study of an acute poisoning incidence with a CP containing pesticide formulation. An initial mass spectrometric screening performed with unprocessed urine samples revealed that CP is not excreted unchanged by the kidney. Hence, the quantitative assay was validated for DETP (quantifier transition: m/z 169-->95, qualifier transition: m/z 169-->141), DEP (m/z 153-->79, 153-->125), and TCP (m/z 196-->35, 198-->35) taking dibutyl phosphate (DBP) (m/z 209-->79, 209-->153) as internal standard. Clean-up of urine samples prior to LC-ESI-MS/MS analysis was carried out by a liquid-liquid extraction step with a mixture of ethylacetate and acetonitrile (70:30; v/v). Linearity was observed between 0.25 and 75 mgL(-1), and the signal-to-noise ratio at 0.25 mgL(-1) was better than six for the individual analytes. Recoveries, precision, and accuracies were all adequate across the validated range of 1-75 mgL(-1) for the present toxicological case study.

Hazard evaluation for northern bobwhite quail (Colinus virginianus) exposed to chlorpyrifos-treated turf and seed

This study evaluated the toxicity effects of chlorpyrifos on bobwhite quail (Colinus virginianus) kept in 27 field-exposed large pens arranged over turf in a randomized block design with nine blocks of three pens (16 adult birds per pen). Nine pens were treated with one application of 3.4 kg active ingredient (ai) per hectare followed by a second 3.4 -kg ai/ha application 2 weeks later, nine pens with one 6.7 -kg ai/ha application, and nine pens with formulation blank. In addition, the seed fed to the birds in the two chemically treated pens was also treated with chlorpyrifos. Mean residue in the grass samples from the first 3.4-kg treatment pens ranged from 306+/-95 ppm on day 0 to 18+/-8 ppm on day 14 after treatment. The second 3.4 -kg ai/ha treatment grass residues ranged from 361+/-167 ppm on day 0 to 38+/-24 ppm on day 14 after treatment. Grass residues from the 6.7-kg treatment pens ranged from 903+/-310 ppm on day 0 to 9+/-8 ppm on day 30 after treatment. Half-lives were approximately 2 days and 10 days for grass and seeds, respectively. Whereas the incidence of behavioral deficits was significantly (P = 0.0156) higher in the 6.7-kg pens (five females, one male), two of the females could have been the same bird because they were both seen in the same pen on days 23 and 24 after treatment. There was no significant difference in mortality, brain acetylcholinesterase activity, or any other measured parameter among any of the treatments. We conclude that application of chlorpyrifos to turf at 3.4 and 6.7 kg ai/ha is not expected to have chronic deleterious effects on populations of bobwhite quail grazing on treated grass or seeds, provided there is an abundant supply of seeds for the quail to eat.

Effects of herbicide and insecticide interaction on soil entomofauna under maize crop

The aim of this study was to evaluate the impact of the herbicide mixture nicosulfuron + atrazine, with or without the insecticide chlorpyrifos, onto soil entomofauna under maize crop. The treatments, applied 25 days after maize emergence, were represented by a weeded control without insecticide and herbicide, a weeded control with chlorpyrifos, and mixtures of nicosulfuron + atrazine, with or without chlorpyrifos. Arthropods populations, on the soil surface, as well as inside the soil under maize, were principally represented by mites (Arachnida: Acari), decomposer collembolans (Hexapoda:Parainsecta:Collembola) and predator ants (Hymenoptera:Formicidae). The nicosulfuron + atrazine mixture with chlorpyrifos and the isolated chlorpyrifos reduced the population dynamics of all insect groups on the soil surface compared to the weeded control. In the soil, mite and ant populations were reduced after application of the herbicide mixture with chlorpyrifos and of the isolated chlorpyrifos.

The relationship of urinary metabolites of carbaryl/naphthalene and chlorpyrifos with human semen quality

Most of the general population is exposed to carbaryl and other contemporary-use insecticides at low levels. Studies of laboratory animals, in addition to limited human data, show an association between carbaryl exposure and decreased semen quality. In the present study we explored whether environmental exposures to 1-naphthol (1N), a metabolite of carbaryl and naphthalene, and 3,5,6-trichloro-2-pyridinol (TCPY), a metabolite of chlorpyrifos and chlorpyrifos-methyl, are associated with decreased semen quality in humans. Subjects (n=272) were recruited through a Massachusetts infertility clinic. Individual exposures were measured as spot urinary concentrations of 1N and TCPY adjusted using specific gravity. Semen quality was assessed as sperm concentration, percent motile sperm, and percent sperm with normal morphology, along with sperm motion parameters (straight-line velocity, curvilinear velocity, and linearity). Median TCPY and 1N concentrations were 3.22 and 3.19microg/L, respectively. For increasing 1N tertiles, adjusted odds ratios (ORs) were significantly elevated for below-reference sperm concentration (OR for low, medium, and high tertiles = 1.0, 4.2, 4.2, respectively; p-value for trend =0.01) and percent motile sperm (1.0, 2.5, 2.4; p-value for trend = 0.01). The sperm motion parameter most strongly associated with 1N was straight-line velocity. There were suggestive, borderline-significant associations for TCPY with sperm concentration and motility, whereas sperm morphology was weakly and nonsignificantly associated with both TCPY and 1N. The observed associations between altered semen quality and 1N are consistent with previous studies of carbaryl exposure, although suggestive associations with TCPY are difficult to interpret because human and animal data are currently limited.

Pesticides and lung cancer risk in the agricultural health study cohort

The authors examined the relation between 50 widely used agricultural pesticides and lung cancer incidence in the Agricultural Health Study, a prospective cohort study of 57,284 pesticide applicators and 32,333 spouses of farmer applicators with no prior history of lung cancer. Self-administered questionnaires were completed at enrollment (1993-1997). Cancer incidence was determined through population-based cancer registries from enrollment through December 31, 2001. A lung cancer standardized incidence ratio of 0.44 (95% confidence interval: 0.39, 0.49) was observed overall, due in large part to a low cigarette smoking prevalence. Two widely used herbicides, metolachlor and pendimethalin (for low-exposed groups to four higher exposure categories: odds ratio (OR) = 1.0, 1.6, 1.2, 5.0; p(trend) = 0.0002; and OR = 1.0, 1.6, 2.1, 4.4; p(trend) = 0.003, respectively), and two widely used insecticides, chlorpyrifos and diazinon (OR = 1.0, 1.1, 1.7, 1.9; p(trend) = 0.03; and OR = 1.0, 1.6, 2.7, 3.7; p(trend) = 0.04, respectively), showed some evidence of exposure response for lung cancer. These excesses could not be explained by previously identified lung cancer risk factors. The usage levels in this cohort are considerably higher than those typically experienced by the general population. An excess risk among spouses directly exposed to pesticides could not be evaluated at this time.

Attempted Suicide by Ingestion of Chlorpyrifos: Identification in Serum and Gastric Content by GC-FID/GC-MS

A mild case of self-poisoning with a chlorpyrifos formulation following oral ingestion is reported. A 15-year-old female went to the emergency room after the ingestion of a product from a bottle marked with a label "Poison". On admission, she was obtunded, with normal vital signs and a strong smell of solvent. Therapeutic measures included the application of decontamination procedures, oxygen, and gastric protectors. She had a good outcome with mild CNS depression and bradycardia. Two hours after ingestion, biological samples were collected in the emergency room and sent for analysis to our laboratory with instructions to investigate the presence of solvents. The serum and gastric content contained 5.3 and 9.4 microg/mL of unmetabolized chlorpyrifos, 4.6 and 6.9 microg/mL of toluene, and 2.5 and 7.9 microg/mL of butyl acetate, respectively. Small traces of other solvents and tetradifon were also detected. Toxicological analyses were negative for ethanol, other volatile solvents, and common drugs of abuse. The simultaneous determination of chlorpyrifos, toluene, and butyl acetate was performed using the combination of gas chromatography (GC)-flame ionization detection for screening analysis and GC-mass spectrometry for confirmation of the obtained results. The method provides an excellent and rapid tool for use in cases of pesticide poisonings, allowing the simultaneous detection of the pesticide and distillates in the performance of systematic toxicological analysis in forensic and clinical laboratories.

In utero pesticide exposure, maternal paraoxonase activity, and head circumference

Although the use of pesticides in inner-city homes of the United States is of considerable magnitude, little is known about the potentially adverse health effects of such exposure. Recent animal data suggest that exposure to pesticides during pregnancy and early life may impair growth and neurodevelopment in the offspring. To investigate the relationship among prenatal pesticide exposure, paraoxonase (PON1) polymorphisms and enzyme activity, and infant growth and neurodevelopment, we are conducting a prospective, multiethnic cohort study of mothers and infants delivered at Mount Sinai Hospital in New York City. In this report we evaluate the effects of pesticide exposure on birth weight, length, head circumference, and gestational age among 404 births between May 1998 and May 2002. Pesticide exposure was assessed by a prenatal questionnaire administered to the mothers during the early third trimester as well as by analysis of maternal urinary pentachlorophenol levels and maternal metabolites of chlorpyrifos and pyrethroids. Neither the questionnaire data nor the pesticide metabolite levels were associated with any of the fetal growth indices or gestational age. However, when the level of maternal PON1 activity was taken into account, maternal levels of chlorpyrifos above the limit of detection coupled with low maternal PON1 activity were associated with a significant but small reduction in head circumference. In addition, maternal PON1 levels alone, but not PON1 genetic polymorphisms, were associated with reduced head size. Because small head size has been found to be predictive of subsequent cognitive ability, these data suggest that chlorpyrifos may have a detrimental effect on fetal neurodevelopment among mothers who exhibit low PON1 activity.

Intermediate syndrome after exposure to chlorpyrifos in a 16-month-old girl

We describe a case of intermediate syndrome after chlorpyrifos ingestion in a toddler, despite a continuous pralidoxime infusion. A 16-month-old girl ingested a pesticide containing chlorpyrifos. She was brought to an Emergency Department where she became lethargic and tachycardic, and subsequently developed pulmonary edema requiring mechanical ventilation. Pralidoxime 150 mg i.v. was administered twice, and an infusion begun at 15 mg/kg/h. At 24.5 h post-ingestion the child had a normal neurologic examination, showed no signs of cholinergic excess, and was extubated successfully. At 27.5 h post-ingestion the child became flaccid, bradycardic and apneic. She was emergently re-intubated. The child's delayed onset of respiratory arrest and flaccid paralysis after an asymptomatic period is consistent with Intermediate Syndrome. This is an unusual case in that it occurred in a young child, was related to chlorpyrifos, and occurred despite continuous and adequate oxime therapy.

Permanent Paralysis at Sites of Dermal Exposure to Chlorpyrifos

OBJECTIVE

Poisoning with organophosphate pesticides can cause sensory and motor neuropathy with permanent paralysis. Paralysis at the site of dermal exposure has not been reported.

CASE REPORT

A 61-year-old carpenter sprayed a nest of termites with an insecticide containing chlorpyrifos without protective equipment and with direct contact of pesticide solution to hands, lower arms, feet, and lower legs, as well as inhalation of vapors from spraying. After 30 min he became ill with nausea, abdominal cramping, arm and leg weakness, bilateral shoulder pain, chest pain, and numbness in the left hand and arm. At a hospital, he was treated with atropine 1 mg IV and pralidoxime Cl 2 g IV There was 0/5 strength in the hands and wrists and 3/5 elsewhere, a left peritoneal palsy, and urinary retention. He was transferred to a tertiary care hospital where paralysis persisted. Electromyogram studies documented widespread peripheral neuropathy. With continued progression of neuropathy, pralidoxime was repeated on the third day. By day 12, motor strength improved except for the hands and left lower leg. Right interosseous muscle strength was 1/5 and left was 0/5. Right-hand grip was 2/5, and left-hand grip was 0/5. He was transferred to a rehabilitation center. He never regained use of his hands and was disabled from employment as a carpenter. There was a disturbed gait, with inability to clear his left foot with walking. Urinary retention persisted and required self-catherization.

CONCLUSION

Dermal exposure of the hands and feet to chlorpyrifos was associated with atrophy and permanent paralysis of exposed areas. The importance of protective equipment is emphasized.

Reduction in the sex ratio of the progeny of a parasitoid wasp (Trichogramma brassicae) surviving the insecticide chlorpyrifos

Due to the wide use of insecticides and their contribution to environmental pollution, the determination of their sublethal effects on the reproduction of parasitoids regulating pest populations is a necessity. In this work, sublethal effects of a lethal dose 20% of chlorpyrifos on the reproduction and the sex ratio of Trichogramma brassicae were assessed. The organophosphorus insecticide chlorpyrifos is one of the most used insecticides for agricultural and domestic purposes in a worldwide market. A decrease in the number of parasitized hosts was observed for females surviving the insecticide. Furthermore, while untreated females presented a very biased sex ratio in favor of daughters, the offspring of treated females surviving the insecticide presented an almost balanced sex ratio due to a decrease in the number of daughters. This decrease in sex ratio was interpreted to be resulting from a decrease in fertilized eggs due to the perturbation of nerve transmissions induced by the insecticide. These results highlight the need for considering not only the direct mortality induced by insecticides but also sublethal effects liable to modify important fitness traits involved in the dynamic of beneficial insect populations.

Organophosphate poisoning complicated by a tachyarrhythmia and acute respiratory distress syndrome in a child

A 9-year-old child presented with documented organophosphate insecticide poisoning. His course was initially complicated by a tachyarrhythmia with QT-interval prolongation that responded promptly to intravenous magnesium. However, following partial recovery, he developed progressive acute respiratory distress syndrome characterized by irreversible fibrosis and obliteration of the lung parenchyma.

Evaluation of acute sensory--motor effects and test sensitivity using termiticide workers exposed to chlorpyrifos

Sensory and motor testing was performed on a group of termiticide workers primarily using chlorpyrifos-containing products to evaluate both the acute effects from current exposure and sensitivity of the measures to detect effects. The study group comprised 106 applicators and 52 nonexposed participants. Current exposure was measured by urinary concentrations of 3,5,6-trichloro-2-pyridinol (TCP) collected the morning of testing. The mean TCP value for the 106 applicators was 200 microg/g creatinine. Participants received 4--5 h of testing and were evaluated using a sensory--motor test battery recommended by a National Institute for Occupational Safety and Health (NIOSH)-sponsored advisory panel to be appropriate for testing effects from pesticide exposures. Measurements testing olfactory dysfunction, visual acuity, contrast sensitivity, color vision, vibrotactile sensitivity, tremor, manual dexterity, eye--hand coordination, and postural stability were analyzed. Study results indicated limited acute effects from exposure to chlorpyrifos using urinary TCP as a measure of current exposure. The effects occurred primarily on measures of postural sway in the eyes closed and soft-surface conditions, which suggests a possible subclinical effect involving the proprioceptive and vestibular systems. Several other tests of motor and sensory functions did not show any evidence of acute exposure effects, although statistically significant effects of urinary TCP on the Lanthony color vision test scores and one contrast sensitivity test score were found. The visual measures, however, were not significant when a step-down Bonferroni correction was applied. Information also is presented on the sensitivity of the measures to detect effects in an occupationally exposed population using standard error of the parameter estimates.

Intermediate syndrome secondary to ingestion of chlorpiriphos

A rural-area resident male patient deliberately ingested chlorpiriphos, an organophosphate insecticide. Although presented with cholinergic symptoms initially, he suffered general condition deterioration after 4 d characterized by muscular weakness, hypotonia, arreflexia and recumbent dyspnea requiring ventilatory support. These clinical manifestations occur from liposoluble organophosphates or metabolites with long-lasting half time, causeing delayed inhibition of acetylcholinesterase and subsequent burn out of the neuromuscular junction from acetylcholine overstimulation.

Protective effects of zinc in chlorpyrifos induced hepatotoxicity: a biochemical and trace elemental study

The toxicological literature is replete with studies attempting to explain the mechanism of action of organophosphorus (OP) insecticides to their anticholinesterase activities, but not much is known about the metabolism and detoxification of these compounds. The goal of this study was to ascertain the toxic effects of chlorpyrifos, one of the most widely used OPs, on the liver of male rats and also to evaluate the protective potential of zinc in mediating its toxic effects. It was observed that chlorpyrifos (13.5 mg/kg body weight) treatment resulted in significant inhibition (p < 0.001) of serum and hepatic acetylcholinesterase (AChE) activities after 8 wk. However, zinc-treated (227 mg/L drinking water) animals resulted in significant normalization of the inhibited AChE activities. Similarly, a significant increase in the levels of various serum and liver marker enzymes (viz. alkaline phosphatase, aspartate aminotransferase [AST], and alanine aminotransferase [ALT]) was observed following treatment with chlorpyrifos. However, coadministration of zinc to these animals restored these enzymes to within normal limits, even though some increase in the activity of serum ALT and hepatic alkaline phosphatase still persisted at the end of the study. Chlorpyrifos treatment diminished serum and hepatic zinc levels significantly (p < 0.01 to p < 0.001) compared to normal control animals. Serum iron concentrations also plummeted significantly following chlorpyrifos treatment. On the contrary, serum copper levels were significantly increased (p < 0.01) in chlorpyrifos-treated animals, but they were normalized following zinc supplementation to the rats in this group. Interestingly, chlorpyrifos treatment resulted in elevated hepatic levels of copper, iron, and selenium, but zinc treatment could only partially restore the raised elemental concentrations. These data clearly demonstrate the potential role of zinc in mediating the toxic effects of chlorpyrifos, presumably because of their antioxidant properties and also their possible interaction with other trace elements in maintaining the cellular harmony.

Administration of succinylcholine for electroconvulsive therapy after organophosphate poisoning: a case study

A 53-year-old man was admitted to the hospital psychiatric unit for evaluation and treatment following a recent suicide attempt, which involved ingestion of an unknown amount of Dursban (DowElanco, Indianapolis, Ind) and a self-inflicted knife wound to the abdomen. Dursban is a commercially prepared organophosphate insecticide in which the active ingredient is chlorpyrifos in a petroleum distillate solvent. The patient received 7 electroconvulsive therapy treatments during a 2-week hospital stay. The anesthetic regimen included methohexital for induction and succinylcholine for neuromuscular relaxation. Cholinesterase levels were low on admission at 5,780 IU (reference range, 11,000-15,000), yet succinylcholine was used successfully at low doses.

Pitfalls when determining tissue distributions of organophosphorus chemicals: sodium fluoride accelerates chemical degradation

This paper describes the tissue distributions of dichlorvos, an organophosphate, and chlorpyrifos-methyl, an organophosphorothioate, in a male individual who died after ingesting an insecticidal preparation containing these chemicals and the results of an in vitro stability study on dichlorvos and chlorpyrifos-methyl in blood and buffers. Tiny amounts of dichlorvos, 0.067 and 0.027 mg/L, were detected in the vitreous humor and cerebrospinal fluid, respectively. Although dichlorvos (0.082-8.99 mg/L or mg/kg) was detected in the thoracic aortic blood, thoracic inferior vena caval blood, pericardial fluid, bile, and spleen, it was strongly suggested that it had diffused postmortem from the stomach, which contained 879 mg, because no dichlorvos was detected in the other blood samples and tissues tested. Substantial amounts (0.615-4.15 mg/L) of chlorpyrifos-methyl were detected in all blood samples, and the order of its concentrations was as follows: pulmonary vessel blood > thoracic inferior vena caval blood > blood in the right cardiac chambers > blood in the left cardiac chambers approximately thoracic aortic blood > right femoral venous blood. The total amount of chlorpyrifos-methyl in the stomach was 612 mg. However, it was strongly suggested that virtually no chlorpyrifos-methyl diffused from the stomach into surrounding fluids and tissues postmortem because no chlorpyrifos-methyl was detected in the bile and little was found in the pericardial fluids. Neither compound was detected in the urine. In vitro experiments showed that dichlorvos (10 mg/L) almost disappeared from fresh (pH 7.4) and acidified (pH 6.2) blood samples within 24 and 72 h, respectively. However, 53 and 77% of the original amount of dichlorvos in 0.05M phosphate buffers at pH 7.4 and 6.2 were detected 72 h later. Chlorpyrifos-methyl (1 mg/L) was very stable in blood samples, regardless of the pH, during the 72-h study period, but in the pH 7.4 and 6.2 phosphate buffers, approximately 80% of the original amount had degraded after 72 h. These results indicate that organophosphates are degraded more rapidly by esterase activities than by chemical mechanisms and that organophosphorothioates are hydrolyzed chemically in aqueous solutions but are very stable in biological specimens and not metabolized by esterases. When sodium fluoride was added to blood samples, dichlorvos degraded completely within 15 min, and chlorpyrifos-methyl became very unstable. Thus, when analyzing samples to detect organophosphorus chemicals, this common preservative should not be added to fluid specimens.

Chlorpyrifos: a ten-year US poison center exposure experience

We performed a retrospective review of data based on poison center exposure inquiries related to chlorpyrifos (CP) and the corresponding poison center-determined medical outcomes reported to the Toxic Exposure Surveillance System (TESS) of the American Association of Poison Control Centers. Ten y (1985-1994) of TESS data were obtained. Medical outcomes representing all inquiries, accidental/unintentional inquiries, and intentional/suicidal inquiries were tabulated. Published TESS data was also tabulated to allow comparison of CP exposure inquiries to all non-pharmaceutical and insecticides/pesticides exposure inquiries for like time periods. Frequency of antidote use, product sales data, CP-related fatality reports, and pertinent issues related to telephone derived surveillance data were also reviewed; 36, 183 CP exposure inquiries were identified. Of all CP exposure inquiries, 27, 473 (75.9%) were assessed as having no significant health consequences; 4,511 (12.5%) outcomes were judged unrelated and 2,980 (8.2%) were unable to be followed. Reported significant medical outcomes for the remaining exposure inquiries were moderate 1,092 (3.0%), major 119 (0.3%) and death 8 (0.02%). Considering only calls with outcomes judged causally related to CP, where a given level of effect could reasonably be determined, 95.8% (27,473/28,692) of these calls resulted in no significant health effects. Use of antidotes specific to organophosphates were infrequent [atropine, 1.0% (385) and 2-PAM, 0.5% (177) of all cases respectively]. Despite the number of reported CP exposure inquiries, relatively few resulted in outcomes of consequence. TESS data suggested that the majority of patients undergoing medical evaluation and/or treatment after a suspected CP exposure do not require specific antidotes. TESS data serves as a useful first step in evaluating product safety. Assessment of product toxicity requires additional investigation of reported adverse effects and circumstances related to the incident.

Pralidoxime continuous infusion in the treatment of organophosphate poisoning

OBJECTIVE

To report a case of organophosphate poisoning treated with a continuous infusion of pralidoxime chloride.

CASE SUMMARY

A 27-year-old white man presented with extreme agitation, muscle weakness and fasciculations, and respiratory failure after ingesting an organophosphate pesticide (Dursban, active ingredients chlorpyrifos and xylene) as a suicide attempt. Atropine sulfate and pralidoxime chloride were administered intermittently, but the patient continued to be extremely agitated and have muscle fasciculations. Subsequently, a continuous intravenous infusion of pralidoxime (8 mg/mL concentration) at 500 mg/h was initiated to help control breakthrough nicotinic symptoms. Therapy with atropine and pralidoxime was continued for approximately 72 hours. Therapy was discontinued due to the predominance of anticholinergic symptoms and the patient's increased awareness.

DISCUSSION

Severe organophosphate poisoning with nicotinic and/or central manifestations should be treated with pralidoxime in addition to atropine. The rationale supporting the use of pralidoxime as a continuous infusion in this case includes: (1) slow absorption of organophosphate compounds following exposure to large quantities, (2) unknown quantity ingested, (3) delayed nicotinic effects from redistribution of lipid-soluble organophosphate and metabolic activation of phosphorothioates such as chlorpyrifos, and (4) intensive care monitoring. There is limited documentation in the literature of continuous infusions of pralidoxime used to treat organophosphate poisoning and the stability of the admixture is unknown.

CONCLUSIONS

A continuous pralidoxime infusion successfully managed the prolonged nicotinic symptoms seen after ingestion of an organophosphate. A continuous infusion of pralidoxime may be particularly useful in cases of organophosphate poisoning when the extent of chemical exposure or quantity of chemical ingested is unknown but potentially toxic and the therapy must be symptomatically managed.

Life-threatening organophosphate-induced delayed polyneuropathy in a child after accidental chlorpyrifos ingestion

Life-threatening organophosphate-induced delayed polyneuropathy with transient bilateral vocal cord paralysis occurred in a 3-year-old child. Recovery was slow after prolonged ventilatory support. Patients who recover from serious organophosphate intoxications should be closely monitored for the development of organophosphate-induced delayed polyneuropathy.

Column extraction of chlorpyrifos from contaminated fish

A method for measuring chlorpyrifos in fish, which combines extraction, filtration, and cleanup in one step, is described. Minced fish samples were mixed with potassium dihydrogen phosphate and disodium hydrogen phosphate, ground with anhydrous sodium sulfate, and eluted from a prepacked chromatographic column containing silica gel. The endogenous coextractives were retained by the column while chlorpyrifos was quantitatively eluted with 40 mL of 5% ether in hexane. Recoveries averaged 86.8% for unexposed fish fortified with 2-12 ppm of chlorpyrifos. The method was applied to the analysis of fish from a lagoon contaminated with chlorpyrifos by a spray treatment of a wooden bridge for termites.

Chlorpyrifos toxicosis in two cats

Organophosphate compounds are widely employed for control of external parasites in cats and for control of insects in homes and yards. Chlorpyrifos is a long-acting organophosphate (OP) available for use as a systemically and topically acting parasiticide and insecticide in cattle. Its use on cats is not recommended, and no previous clinical cases of toxicosis have been described. Two cases of chronic chlorpyrifos toxicosis in cats are presented and pathophysiology as well as treatment are discussed. The cats had been showing signs of chronic organophosphate toxicosis before diazepam administration. Signs of acute organophosphate toxicosis were precipitated after diazepam was given. Treatment with pralidoxime chloride (2-PAM) and atropine was attempted. Response to treatment was dramatic and complete recovery was achieved with six injections of pralidoxime and atropine administration.

Conditioning of physical symptoms after neurotoxic exposure

Psychologic reactions to a neurotoxic exposure can produce prolonged physical symptoms which are as debilitating as the direct effects of the neurotoxic substance. A group of patients exist who experience reoccurrence of exposure-related symptoms when exposed to a variety of common environmental substances, such as perfume, gasoline, and cigarette smoke. We propose a classical conditioning model to explain the development of this phenomenon. Identification and treatment of these individuals are also discussed.

Toxicologic evaluation of chlorpyrifos in cats

Twenty-four male domestic shorthair cats were used to evaluate the acute and chronic effects of a single, toxic but sublethal, orally administered dose of chlorpyrifos. A dosage of 10 mg/kg of body weight did not induce clinical signs of toxicosis, but a dosage of 40 mg/kg induced clinical signs of toxicosis, and 1 of 12 cats died. Chlorpyrifos given at a dosage of 0.1 mg/kg to 2 cats reduced whole blood and plasma cholinesterase (Che) activities to values obtained after cats were given doses that induced clinical signs of toxicosis. Regeneration time for whole blood and plasma Che activities ranged from 7 to 28 days. Brain Che activity was considerably decreased in 1 cat that died 4.5 hours after dosing, but was normal in all others at 28 days after dosing. Other than decreased Che activity, significant changes were not seen in hematologic or serum biochemical values. Toxin-related lesions were not seen during macroscopic or microscopic examination.

Chlorpyrifos poisoning treated with ipratropium and dantrolene: a case report

A patient suffering from chlorpyrifos poisoning and manifesting copious endotracheal secretions was successfully treated by inhalation of ipratropium.

Toxicosis in newborn pigs associated with cutaneous application of an aerosol spray containing chlorpyrifos

Weakness, lethargy, ataxia, lateral recumbency, limb paddling, tremors, salivation, and diarrhea were observed in newborn pigs on a commercial swine farm. Many pigs became moribund and died. All had been treated with an aerosol wound spray containing 2.5% chlorpyrifos. A controlled study was undertaken to determine whether the aerosol spray was the cause of these clinical signs. Pigs exposed to aerosol spray containing 2.5% chlorpyrifos at 3 hours (n = 4) and 6 hours (n = 3) after birth developed clinical signs similar to those on the farm; none survived. Pigs exposed at 24 hours (n = 5) after birth developed clinical signs consistent with those that had developed in pigs on the farm; 3 died and 2 survived. Of 3 pigs exposed to the same spray at 36 hours after birth, 1 developed tremors 7.5 hours later and diarrhea 9 hours later, then returned to normal.