Subclinical health effects of environmental pesticide contamination in a developing country: cholinesterase depression in children.

The effect of exposure to pesticides among children in a Nicaraguan community in the path of rain water runoff from a large crop-dusting airport was evaluated by measuring plasma cholinesterase. Mean cholinesterase activity in 17 children in the path of runoff was 2.4 international units/ml blood/min, lower than the 2.9 IU/ml/min measured in a group of 43 children from an unexposed community (difference=0.49 IU/ml/min; 95% C.I. 0.24, 0.76). Six (35%) of the 17 exposed children had abnormally low cholinesterase levels. A possible explanation for this physiological effect of exposure to pesticides is the dermal absorption which may have occurred among children playing barefoot in puddles grossly contaminated by runoff from the airport. Drinking water from a well in the exposed community demonstrated low level residues of cholinesterase-inhibiting pesticides, although contamination with toxaphene (not a cholinesterase inhibitor) exceeded by over 8-fold the United States Environmental Protection Agency maximum permissible concentration in drinking water. The difficulty in measuring health effects resulting from environmental pesticide contamination, and in controlling exposure resulting from the rapidly increasing use of pesticides, is a growing problem for developing countries like Nicaragua.

Electrocardiogram pattern in hypercholesterolemic women: the influence of hormone replacement therapy.

OBJECTIVE: The aim of this study was to delineate electrocardiogram (ECG) patterns in postmenopausal women with hypercholesterolemia and to assess the possible influence of female sex hormones. STUDY DESIGN: A total of 72 postmenopausal women with moderately elevated total cholesterol levels constituted the case group, of which 48 came from a clinical trial and 24 from a cohort study. Some 236 women aged 50-59 years with normal levels of cholesterol were participants in the same cohort study in the local area. These 236 women had been subdivided into three groups: premenopausal, postmenopausal and postmenopausal with hormone replacement therapy (HRT). Of the 48 women in the clinical study group, 12 patients showed pathological ECG changes. Six of these patients were treated with HRT for 2 years (transdermal estradiol 50 micrograms/day and a daily dose of 5 mg medroxyprogesterone acetate, MPA) and the rest were non-users of HRT. RESULTS: In the women with hypercholesterolemia, 16 of 72 patients (22%) showed ischemic ECG changes, compared to nine of 88 (10%) with normal cholesterol levels (p = 0.04). We found no significant difference in the prevalence of ECG changes between postmenopausal women with and without HRT in the groups with normal levels of cholesterol. In the hormone treatment group, four of six patients showed an improvement in ECG pattern, in contrast to two of six non-users of HRT. CONCLUSIONS: This preliminary study revealed a higher prevalence of pathological ECG changes in postmenopausal women who had hypercholesterolemia than in normocholesterolemic women. These findings support the idea that hyperlipidemia contributes to the overall increase in cardiovascular disease, as this is also associated with ECG changes. Transdermal estradiol combined with MPA has a beneficial effect in reversing the process of atherosclerosis, as well as improving the ECG pattern. The prevalence of pathological ECG patterns was similar for HRT users and non-users. This outcome may be affected by several factors. Hence, further research is warranted.

Liquid chromatographic determination of bromide ion in cereals, fruit, vegetables, and blood with a silver electrode in an electrochemical detector system.

A method is presented for rapid determination of bromide ion in commodities and blood by paired-ion liquid chromatography with electrochemical detection. The method involves extraction of samples with water and filtration. Blood is passed through a Sep-Pak C18 minicolumn. Recoveries are usually close to 100%, with satisfactory precision. The detection limit is 1 mg/kg. The method needs little labor and uses no noxious solvents or reagents.

Pesticide management in food and water safety: international contributions and national approaches.

The obvious advantages of the use of pesticides is hampered by the risks they can pose to humans and the environment. Sound evaluations of pesticides and easy access to these evaluations will help nations to choose those pesticides that will create the fewest risks. There are now about 50 international organizations, approximately 15 of them within the United Nations system, with some engaging in pesticide evaluations and regulations. The present survey of 72 pesticides of major global economic importance reveals that there is a lack of data for many of these pesticides, whereas others might be subjected to duplicate work and even confusing regulations. More joint programs and intensified information on ongoing activities, both internationally and nationally, should be encouraged. WHO has classified 71 of the 72 pesticides according to hazard for people handling them. International cancer risk classifications exist for three of them (IARC 1987), and U.S. EPA cancer classifications for 18. The availability of pesticides impacts humans and the environment. FAO/WHO has recommended different degrees of restrictions on the availability of 16 of the pesticides. According to United Nations Headquarters (1987), 20 of the 72 pesticides have been banned, withdrawn, or severely restricted in one or more countries. ADIs have been suggested for 31 of the 72 pesticides by FAO/WHO. Nationally, U.S. EPA has established reference doses for 44 of the pesticides. MRLs have been set by FAO and WHO for 31 of the pesticides in food and by WHO for 12 in drinking water. Nationally, there are great variations in tolerance levels as well as in rules for setting these tolerances, including group tolerances for related pesticides. For the monitoring of pesticide residues in food, U.S. FDA has classified pesticides in a surveillance index to establish monitoring needs. Thirty-five of the 72 pesticides of major economic importance are included. In a typical monitoring program (Sweden), 29 of the 72 pesticides are included. It is concluded that there is a lack of accessible information on evaluations and regulations of many of the most economically important pesticides. The need for intensified assessments is stressed. The relevant United Nations agencies as well as certain independent research institutes, such as the British Monitoring and Assessment Research Center (MARC), need increased encouragement and financial support from United Nations member states to fulfill this task.

Ion-pair extraction cleanup for liquid chromatographic determination of bentazon in crops and soil.

Bentazon was selectively extracted as an ion pair with tetrabutylammonium ion into dichloromethane. This technique was used to clean up crop and soil samples before determination of bentazon by reverse phase liquid chromatography and UV detection. Recoveries from potatoes, cucumbers, wheat grain, and clay soil were 77-103%, with a detection limit of 0.02 mg/kg.

Studies on phenoxy acid herbicides. I. Field study. Occupational exposure to phenoxy acid herbicides (MCPA, dichlorprop, mecoprop and 2,4-D) in agriculture.

In the presented study we wanted to establish a biological monitoring of exposure in farmers occupationally exposed to phenoxy acid herbicides (MCPA, dichlorprop mecoprop, and 2,4-D). The individual airborn concentrations were measured as well as the urinary concentration before, during and after exposure. Twentyfour male farmers and nine professional spray-men were studied and compared. The air concentrations were low, less than 0.001-0.1 micrograms/m3. Urinary concentrations were variable less than 0.05-12 micrograms/ml (MCPA). Uptake by dermal absorption seems to be dominant, swallowing of sprayed droplets and inhalation are possible routes of entrance. Urinary concentrations of phenoxy acid herbicides (MCPA, dichlorprop, and mecoprop) measured at the end of an exposure period or preferably the following morning could be used to give a reflection of recent exposure.

Studies on phenoxy acid herbicides. II. Oral and dermal uptake and elimination in urine of MCPA in humans.

Five healthy volunteers were given 15 micrograms MCPA per kg body weight. The highest concentration in plasma, 0.15 micrograms/ml, was found after 1 h. In urine the excretion during the first 6 h was 0.46 microgram/min and 40% of given dose was excreted during the first 24 h. About 1 g of MCPA emulsion was applied on the skin of the thigh and was washed away after 2 h. Plasma level slowly increased with maximum, 0.12 micrograms/ml, after 24 h. In urine a slow excretion continued for up to 5 days later with maximum 24-48 h after application. In agricultural field exposure urinary MCPA should be estimated immediately after stop of exposure as well as 24 h after exposure. Levels under 0.5 micrograms/ml of MCPA in urine might be used as a practical biological level for good work practice. In spot samples the concentration of urine must be considered.

Occupational exposure to some synthetic pyrethroids (permethrin and fenvalerate).

In a two-step study on exposure control method for occupational handling of permethrin was developed. Air sampling on a filter can be used in case of exposure to permethrin in powder form. The detection limit is 0.001 mg/m3. If biological sampling is used, the acid metabolite moiety in the urine must be monitored. However, the uptake after exposure to permethrin in forestry was too low, and no urine concentration could be found. The detection limit is 0.1 microgram/ml. Six persons in a plant nursery and six planters were studied in this way. Interviews were conducted with 139 planters. Irritative symptoms form the skin and upper respiratory tract were reported in 73% for fenvalerate, 63% for permethrin (trans/cis 75/25) and 33% for permethrin (trans/cis 60/40).