Acetylcholinesterase (AChE) is a key enzyme in the nervous system. It terminates nerve impulses by catalysing the hydrolysis of neurotransmitter acetylcholine. As a specific molecular target of organophosphate and carbamate pesticides, acetylcholinesterase activity and its inhibition has been early recognized to be a human biological marker of pesticide poisoning. Measurement of AChE inhibition has been increasingly used in the last two decades as a biomarker of effect on nervous system following exposure to organophosphate and carbamate pesticides in occupational and environmental medicine. The success of this biomarker arises from the fact that it meets a number of characteristics necessary for the successful application of a biological response as biomarker in human biomonitoring: the response is easy to measure, it shows a dose-dependent behavior to pollutant exposure, it is sensitive, and it exhibits a link to health adverse effects. The aim of this work is to review and discuss the recent findings about acetylcholinesterase, including its sensitivity to other pollutants and the expression of different splice variants. These insights open new perspective for the future use of this biomarker in environmental and occupational human health monitoring.

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Acetylcholinesterase as a biomarker in environmental and occupational medicine: new insights and future perspectives.

Dietary intake of organophosphorus pesticide residues through vegetables from Kumasi, Ghana.

Public concern about the adverse environmental and human health impacts of organochlorine contaminants led to strict regulations on their use in developed nations two decades ago. Nevertheless, DDT and several other organochlorine insecticides are still being used for agriculture and public health programs in developing countries in Asia and the South Pacific. As a consequence, humans in this region are exposed to greater dietary levels of organochlorines. In this review, published information on organochlorine concentrations in foodstuffs from South and Southeast Asia and Oceanic countries has been compiled. Foodstuffs that contribute to human exposures and dietary intakes of organochlorines were examined, and the data compared with those reported from more developed nations. Among various developing countries in Asia, considerable information on organochlorines in foodstuffs has been available from India since the late 1960s. DDT and HCH were the major insecticides in Indian foodstuffs. Concentrations of these insecticides have declined more than two orders of magnitude in farm products, such as food grains and vegetables, in two decades. Milk and milk products are the major sources of dietary exposure to DDT and HCH in India. The residues of these insecticides in dairy products were close to or above the MRLs of the FAO/WHO. Dietary intake of DDT and HCH by Indians was > 100 fold that in more developed nations. Sporadic incidences of greater concentrations (> 1 microgram/g) of aldrin, dieldrin, and heptachlor have been measured in Indian vegetables. Untreated surface waters could be a potential source of DDT and HCH exposure. In most Southeast Asian countries DDT was the common contaminant in animal origin foodstuffs. The higher percentage of p,p'-DDT in meat and fish from Southeast Asian countries, except Japan and Korea, indicated the recent use of DDt in vector control operations. Dietary intakes of DDt and HCH in Southeast Asia were an order of magnitude less than those of Indians but 5- to 10 fold greater than in more developed nations. In addition to DDT, aldrin and dieldrin were prominent in meat collected from Thailand and Malaysia. Aquatic food products from more industrialized countries, such as Japan, South Korea, Hong Kong, and Taiwan, contained significant levels of PCBs. In South Pacific countries, particularly in Australia and New Zealand, chlordanes and PCBs were the most prevalent organochlorines in foodstuffs. Food contamination by DDT, HCH, aldrin, and dieldrin was less than in developing countries in Asia but greater than in the U.S. and Japan. Intake of PCBs in Australia was greater than in the U.S. Meat and fish were the major sources of organochlorine exposure by Australians. Human dietary intake of organochlorines has been declining more slowly in developing countries in Asia. Current intakes were at least 5- to 100 fold greater than those in more developed nations, suggesting a greater risk from organochlorine exposure. Factors such as malnutrition, common among rural poor in developing nations, can increase these risks. Of greatest concern is the magnitude of exposure to organochlorines to which infants and children are subjected through human and dairy milk. The estimated intake of DDT by infants was at least 100 fold greater than the ADI of the FAO/WHO. In addition to DDT, excessive exposures to HCH and dieldrin may cause potential health effects in infants because they are more vulnerable to toxic effects. The design and implementation of appropriate epidemiological studies and their integration with monitoring of human, food, and environmental samples would be a major step in assessing the risks of organochlorine residues in foods and controlling or eliminating them. With the continued globalization of trade in food products, and the concomitant risk that food contaminated through point-source pollution may be widely distributed, identification of sources and their control should be matters of

Organochlorine Pesticides and Polychlorinated Biphenyls in Foodstuffs from Asian and Oceanic Countries

DISCLAIMER The use of company or product name(s) is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry. A Toxicological Profile for pyrethrins and pyrethroids, Draft for Public Comment was released in September, 2001. This edition supersedes any previously released draft or final profile. Toxicological profiles are revised and republished as necessary, but no less than once every three years. For information regarding the update status of previously released profiles, contact ATSDR at: Toxicological Profiles are a unique compilation of toxicological information on a given hazardous substance. Each profile reflects a comprehensive and extensive evaluation, summary, and interpretation of available toxicologic and epidemiologic information on a substance. Health care providers treating patients potentially exposed to hazardous substances will find the following information helpful for fast answers to often-asked questions. Chapter 1: Public Health Statement: The Public Health Statement can be a useful tool for educating patients about possible exposure to a hazardous substance. It explains a substance's relevant toxicologic properties in a nontechnical, question-and-answer format, and it includes a review of the general health effects observed following exposure. Chapter 3: Health Effects: Specific health effects of a given hazardous compound are reported by type of health effect (death, systemic, immunologic, reproductive), by route of exposure, and by length of exposure (acute, intermediate, and chronic). In addition, both human and animal studies are reported in this section. NOTE: Not all health effects reported in this section are necessarily observed in the clinical setting. Please refer to the Public Health Statement to identify general health effects observed following exposure. The following additional material can be ordered through the ATSDR Information Center: Case Studies in Environmental Medicine: Taking an Exposure History—The importance of taking an exposure history and how to conduct one are described, and an example of a thorough exposure history is provided. Other case studies of interest include Reproductive and Developmental Hazards; Skin Lesions and Environmental Exposures; Cholinesterase-Inhibiting Pesticide Toxicity; and numerous chemical-specific case studies. viii PYRETHRINS AND PYRETHROIDS Managing Hazardous Materials Incidents is a three-volume set of recommendations for on-scene (prehospital) and hospital medical management of patients exposed during a hazardous materials incident. Volumes I and II are planning guides to assist first responders and hospital emergency department personnel in planning for incidents that involve hazardous materials. Volume III— Medical Management Guidelines for Acute Chemical Exposures—is a guide for health care professionals …

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Toxicological profile for pyrethrins and pyrethroids

Monitoring of pesticides and heavy metals in cucumber fruits produced from different farming systems.

Pesticide residues in human milk and environmental samples from Kafr El-Zayat Governorate in Egypt were analyzed. This governorate is located near one of the biggest pesticide factories in Egypt. Organochlorine and organophosphorus pesticides were monitored, including those that have been prohibited from use in Egypt. Human milk samples (31 samples) from Kafr El-Zayat were compared with 11 samples collected from Cairo. Data were compared with results from studies performed in 1987 and 1990. The present study showed that aldrin and dieldrin, heptachlor and heptachlor epoxide, and endrin residues have been eliminated from human milk. Estimated daily intakes (EDIs) of DDT complex and gamma-HCH by breast-fed infants in Kafr El-Zayat were 85.96 and 3.1% of the respective acceptable daily intakes (ADIs). beta-HCH residues showed an increasing pattern, especially in human milk samples from Cairo. DDT complex and HCH isomers in orange, spinach, lettuce, potatoes, and clover samples ranged from undetectable to very low concentrations. Higher levels of DDT and HCH were detected, but aldrin, dieldrin, endrin, and the heptachlors were not detected in food of animal origin. Residues in fish samples were below maximum residue limits established by some developed countries. Those in animal milk samples approached the extraneous residue limits of the Codex Committee on Pesticide Residues. HCH residues in soil were negligible, but DDT residues in soil were somewhat higher. Among water samples, groundwater samples had the highest residues of HCHs and DDTs, followed by Nile River water and then tap water. However, the organochlorine pesticide residues were found at concentrations below the maximum allowable limits set by the World Health Organization for drinking water. Among 12 organophosphorus pesticides monitored as parent compounds, dimethoate, malathion, methamidophos, and chlorpyrifos residues were detected in low concentrations in soil samples from a pesticide factory. No organophosphorus pesticide residues were found in plant samples, except for very low residues of dimethoate in an orange sample. Water samples were devoid of organophosphorus residues as parent compounds.

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Monitoring of pesticide residues in human milk, soil, water, and food samples collected from Kafr El-Zayat Governorate.

Organophosphorus, dithiocarbamates, and some synthetic pyrethroids pesticides, which are commonly used in Egypt for pest control, were monitored, as well as persistent organochlorines, which had been prohibited from use several years ago. Fruit and vegetable samples (397) were collected from 8 local markets and examined for 52 pesticides. Of all analyzed samples, 42.8% contained detectable residues, of which 1.76% exceeded their maximum residue limits (MRLs). The rates of contamination with the different pesticides were 0-86%. However, violation rates among contaminated products were very low, ranging from 0 to 4.6%. In general, organochlorine pesticide residues were not detected in most samples. Dithiocarbamate residues were found in 70.4% of 98 samples analyzed for dithiocarbamates, but only one grape sample had residues exceeding the MRL established by the Codex Committee on Pesticide Residues.

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Monitoring Pesticide Residues in Egyptian Fruits and Vegetables in 1995

A market basket survey was conducted to monitor organochlorine and organophosphorus pesticide residues in potatoes, citrus fruits, and fish collected from local Egyptian markets. Maximum Residue Limits (MRLs) of the Codex Committee on Pesticide Residues for gamma-hexachlorocyclohexane (HCH) in potatoes were exceeded in 8 samples and for DDT in 2 samples. The aging of HCH and DDT indicated a recent use of both pesticides during the potato storage period between cultivation seasons. However, such use is illegal because HCH mixture isomers (gammaxane) and DDT have been officially prohibited from agricultural use in Egypt since 1980. The highest residue levels of fenitrothion (3.8 ppm) in potatoes may be due to its repeated use before and after harvest. No organochlorine pesticide residues were found in citrus fruits. None of the detected organophosphorus pesticides exceeded their MRLs. HCH and DDT residue limits were exceeded in 5 and 7 fish samples, respectively, collected from 12 markets throughout the country. The heptachlor MRL was violated in only one fish sample (3.9 ppm).

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S M Dogheim

Papers

Monitoring of pesticide residues in human milk, soil, water, and food samples collected from Kafr El-Zayat Governorate.

Monitoring Pesticide Residues in Egyptian Fruits and Vegetables in 1995

Organochlorine and organophosphorus pesticide residues in food from Egyptian local markets.