RESUMEN
AIMS: To evaluate the association of acute organophosphate (OP) poisoning with chronic sensory and motor neurological impairment. METHODS: This study concerns the third of a series of three examinations of hand strength and vibration thresholds in a two year period after acute OP poisoning among 48 Nicaraguan men. The first two examinations were performed at hospital discharge and seven weeks after poisoning, and the present examination two years later. Twenty eight cattle ranchers and fishermen who had never experienced pesticide poisoning were examined as controls, also three times over the two year period. The poisonings were categorised as caused by "non-neuropathic" OPs and "neuropathic" OPs, each subdivided in moderate and severe poisonings. RESULTS: Men poisoned with OP insecticides had persistent reduced hand strength. We previously reported weakness at hospital discharge for OP poisoned in all categories that worsened seven weeks later for those severely poisoned with neuropathic OPs. Strength improved over time, but the poisoned were still weaker than controls two years after the poisoning, most noticeably among the subjects most severely poisoned with neuropathic OPs. Also, index finger and toe vibration thresholds were slightly increased at the end of the two year period, among men with OP poisonings in all categories, but patterns of onset and evolvement of impairment of vibration sensitivity were less clear than with grip and pinch strength. CONCLUSIONS: Persistent, mainly motor, impairment of the peripheral nervous system was found in men two years after OP poisoning, in particular in severe occupational and intentional poisonings with neuropathic OPs. This finding is possibly due to remaining organophosphate induced delayed polyneuropathy.
Asunto(s)
Fuerza de la Mano , Insecticidas/envenenamiento , Enfermedades Profesionales/inducido químicamente , Compuestos Organofosforados , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Trastornos de la Sensación/inducido químicamente , Enfermedad Aguda , Adolescente , Adulto , Enfermedad Crónica , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Exposición Profesional/efectos adversos , Umbral SensorialRESUMEN
Pesticides are an extensively documented occupational and environmental hazard in Central America. Yet, severe problems persist. Toxic pesticide use in the Region increased during 1985-1999. High exposure levels and ineffectiveness of personal protective equipment evidence the difficulties for risk reduction. Acute poisonings remain a severe problem. Delayed and/or long-lasting health effects include dermatoses, cancer, and genotoxic, neurotoxic, and respiratory effects. The use of hazardous pesticides persists through deficiencies in government-driven assessment and risk management; excessive focus on regional harmonization; short-term economic interests; strong links between industry and governments; aggressive marketing; weak trade unions; and failure of universities to reach decision makers. Regulation based on local data is lacking. An agreement of the Ministries of Health for restricting the most toxic pesticides in Central America has potential for progress. The most effective way to reduce risk is to greatly reduce pesticide use. Actions needed include development of multidisciplinary strategies for local studies on health and environmental impact of pesticides; development of sustainable nonchemical agricultural technologies; evaluation of interventions; extending and sharing of expertise within the Region; strengthening of unions and communities; and redefining the role of industry toward development of safer products, with responsible marketing and reliable information.
Asunto(s)
Exposición a Riesgos Ambientales/efectos adversos , Sustancias Peligrosas/efectos adversos , Plaguicidas/efectos adversos , Academias e Institutos/tendencias , América Central , Industria Química/tendencias , Exposición a Riesgos Ambientales/estadística & datos numéricos , Humanos , Sindicatos/tendencias , Neoplasias/inducido químicamente , Sector Público/tendencias , Medición de RiesgoRESUMEN
OBJECTIVES: To explore whether symptoms resulted from pesticide spray drift on residentially exposed populations in rural Nicaragua. METHODS: 100 residents, each 10 years of age or older, were randomly selected from a Nicaraguan community surrounded by actively sprayed cotton fields (the exposed community) and from a socioeconomically similar community far from agricultural spraying (the control community). Subjects working with pesticides were excluded, and the study was conducted at the end of the 1990 cotton spraying season (August-December). Demographic information, exposure questions, and prevalence of 11 acute symptoms and 17 chronic symptoms were gathered from a structured interview. Finger stick erythrocyte cholinesterase (AChE) was measured with a portable colorimeter. Acute symptoms were grouped according to their previously known associations with cholinesterase (ChE) inhibitors into four ordinal categories (asymptomatic, non-specific, possible, probable). RESULTS: Residents from the exposed community were significantly more likely to report recently sighting a spray plane near their community, exposure to pesticide from drift, crossing recently sprayed fields, eating home grown food, and feeling ill after drift exposure. The mean AChE value was significantly lower for residents of the exposed community (4.9 v 5.3 IU/dl). The proportion of subjects complaining of one or more chronic or acute symptoms was significantly higher for the exposed community (87%) than for the controls (53%). Odds ratios for residents in the exposed community, by symptom categories, were non-specific 1.6 (95% confidence interval (95% CI) 0-8 to 3.2), possible 4.1 (95% CI 1.7 to 10.2), and probable 9.93 (95% CI 2-9 to 34.4). CONCLUSION: These findings indicate a strong association between exposure to aerial pesticides and symptoms. This study should be replicated with more quantitative exposure measures, for if confirmed, the results have relevance for millions in rural communities worldwide.
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Colinesterasas/análisis , Exposición a Riesgos Ambientales/efectos adversos , Enfermedad Aguda , Estudios de Casos y Controles , Niño , Enfermedad Crónica , Disnea/clasificación , Eritrocitos/enzimología , Femenino , Enfermedades Gastrointestinales/clasificación , Humanos , Masculino , Enfermedades del Sistema Nervioso/clasificación , Nicaragua/epidemiología , Oportunidad Relativa , Plaguicidas/efectos adversos , Prevalencia , Población RuralRESUMEN
Many organophosphorus compounds (OPs) are potent cholinesterase inhibitors, accounting for their use as insecticides and, unfortunately, also as nerve agents. Each year there are approximately 3 million pesticide poisonings world-wide resulting in 220,00 deaths. In 1990, there were 1.36 million kg of chlorpyrifos, 4.67 million kg of diazinon and 1.23 million kg of ethyl parathion manufactured in the USA (data supplied by the USEPA). In addition to exposure risks during pesticide manufacturing, distribution and use, there are risks associated with the major international effort aimed at destroying the arsenals of nerve agents, including soman and sarin. The United States has pledged to destroy approximately 25,000 tons of chemical agents by the end of the decade. The high density lipoprotein (HDL)-associated enzyme paraoxonase (PON1) contributes significantly to the detoxication of several OPs (Fig. 1). The insecticides parathion, chlorpyrifos and diazinon are bioactivated to potent cholinesterase inhibitors by cytochrome P-450 systems. The resulting toxic oxon forms can be hydrolysed by PON1, which also hydrolyses the nerve agents soman and sarin (Fig. 1). PON1 is polymorphic in human populations and different individuals also express widely different levels of this enzyme. The Arg192 (R192) PON1 isoform hydrolyses paraoxon rapidly, while the Gln192 (Q191) isoform hydrolyses paraoxon slowly. Both isoforms hydrolyse chlorpyrifos-oxon and phenylacetate at approximately the same rate. The role of PON1 in OP detoxication is physiologically significant. Injected PON1 protects against OP poisoning in rodent model systems and interspecies differences in PON1 activity correlate well with observed median lethal dose (LD50) values. We report here a simple enzyme analysis that provides a clear resolution of PON1 genotypes and phenotypes allowing for a reasonable assessment of an individual's probable susceptibility or resistance to a given OP, extending earlier studies on this system. We also show that the effect of the PON1 polymorphism is reversed for the hydrolysis of diazoxon, soman and especially sarin, thus changing the view of which PON1 isoform is considered to be protective.
Asunto(s)
Esterasas/sangre , Esterasas/genética , Compuestos Organofosforados/metabolismo , Sarín/metabolismo , Soman/metabolismo , Arildialquilfosfatasa , Sustancias para la Guerra Química/metabolismo , Sustancias para la Guerra Química/farmacología , Resistencia a Medicamentos/genética , Esterasas/efectos de los fármacos , Homocigoto , Humanos , Isoenzimas , Compuestos Organofosforados/farmacología , Polimorfismo Genético , Sarín/farmacología , Soman/farmacología , América del SurRESUMEN
We undertook to estimate the degree of underreporting to a regional pesticide poisoning registry, and to estimate the true incidence of poisoning in an agricultural region of Nicaragua. We surveyed 633 workers at 25 of 33 agricultural cooperatives and any nearby private forms in a area geographically convenient to the regional health headquarters with a short structured interview about pesticide poisonings. Eighty-three percent of workers described current use of pesticides. Twenty-five percent described a pesticide poisoning in the preceding 12 months, and almost one-half (48%) described having been made ill by pesticides at some point in time. Sixty-nine (11%) described a poisoning in the preceding month, 23 of whom had received medical attention. The names of the medically treated were sought in the Regional Pesticide Poisoning Registry for the survey year of 1988. Only 8 of the 23 subjects were found reported to the registry when a total of 1,143 human pesticide poisonings were reported in the entire region. Using 65% as an estimate of underreporting to the registry, we calculate that 3,300 (95% CI 2100-7500) poisonings had received treatment in the region in 1988, of whom more than 2,100 remained unreported. Based on the ratio of total poisonings (treated and untreated) to registry-reported poisonings among our survey respondents, we estimate that 6,700 (95% CI 4100-18000) systemic poisonings, occurred in 1988 in the region. Underreporting of pesticide poisonings disguises the enormity of the problem in developing countries. Even in a region with a strong emphasis on illness reporting for targeted conditions, underreporting is substantial. This method for estimating underreporting is easily applied and provides a rough estimate of registry underreporting and actual incidence for conditions identifiable by a community-applied questionnaire.
Asunto(s)
Enfermedades de los Trabajadores Agrícolas/epidemiología , Plaguicidas/envenenamiento , Sistema de Registros , Adolescente , Adulto , Anciano , Niño , Estudios Transversales , Femenino , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Nicaragua/epidemiología , Intoxicación/epidemiologíaRESUMEN
Acute organophosphate pesticide poisonings cause substantial morbidity and mortality world wide; however, whether organophosphates cause chronic neurological sequelae has not been established. To see whether single episodes of acute unintentional organophosphate intoxication lead to chronic neuropsychological dysfunction, we carried out a retrospective study of agricultural workers in Nicaragua who had been admitted to hospital between July 1, 1986, and July 31, 1988, for occupationally related organophosphate intoxication. This "poisoned" group (36 men) was tested on average about two years after the episode of pesticide poisoning and compared with a matched control group. The poisoned group did much worse than the control group on all neuropsychological subtests, with significantly worse performance on five of six subtests of a World Health Organisation neuropsychological test battery and on 3 of 6 additional tests that assessed verbal and visual attention, visual memory, visuomotor speed, sequencing and problem solving, and motor steadiness and dexterity. Differences in neuropsychological performance could not be explained by other factors. The findings of a persistent decrease in neuropsychological performance among individuals with previous intoxication emphasise the importance of prevention of even single episodes of organophosphate poisoning.