Archives of environmental health最新文献

Samples of human blood sera (N = 118) for the determination of organochlorine pesticide levels were obtained at autopsy from auto accident victims in Veracruz, Mexico, during the years 2000 and 2001. The presence of hexachlorobenzene (HCH), beta-hexachlorocyclohexane (beta-HCH), 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDT), and o,p'-DDT was confirmed by gas-liquid-electron-capture detection chromatography. During the years 2000 and 2001, the respective mean levels of (a) HCB, (b) beta-HCH, (c) p,p'-DDE, (d) o,p'-DDT, (e) p,p'-DDT, and (f) total DDT were (a) 2.1 ng/ml and 1.4 ng/ml, (b) 3.0 ng/ml and 3.6 ng/ml, (c) 21.1 ng/ml and 23.8 ng/ml, (d) 1.2 ng/ml and 0.8 ng/ml, (e) 3.3 ng/ml and 2.5 ng/ml, and, finally, (f) 25.4 ng/ml and 27.1 ng/ml, respectively. High levels of persistent organochlorine pesticides were--and continue to be--present in the blood of individuals who live in Mexico. Levels of insecticide metabolites (e.g., beta-HCH, p,p'-DDE) in blood have increased during recent years (1997-2001), but levels of p,p'-DDT decreased in 2001 because the use of DDT for the control of malaria in Mexico was restricted.

Delayed offline measurement of exhaled nitric oxide (eNO), although useful in environmental and clinical research, is limited by the instability of stored breath samples. The authors characterized sources of instability with the goal of minimizing them. Breath and other air samples were stored under various conditions, and NO levels were measured repeatedly over 1-7 d. Concentration change rates varied positively with temperature and negatively with initial NO level, thus "stable" levels reflected a balance of NO-adding and NO-removing processes. Storage under refrigeration for a standardized period of time can optimize offline eNO measurement, although samples at room temperature are effectively stable for several hours.

The authors examined the relationship of noise sensitivity with health status and psychological factors in individuals <70 yr of age in Finland. Subjects (n = 1,355) were selected from a 1988 case-control study, based on the Finnish Twin Cohort, that assessed noise sensitivity, lifetime noise exposure, and hypertension. Other health status and psychological factors were obtained from a questionnaire that had been administered to the same individuals in 1981. Statistical analysis showed that noise sensitivity was associated significantly with hypertension, emphysema, use of psychotropic drugs (i.e., sleeping pills, tranquilizers, and pain relievers), stress, smoking, and hostility, even after adjustment for lifetime noise exposure. These results indicate that noise sensitivity has both psychological and somatogenic components.

Herbal preparations are gaining popularity worldwide because of their history of use and the belief that they are free of harmful side effects. Among the most popular products are herbal teas, which are marketed extensively with emphasis on their medicinal properties. At the same time, the World Health Organization has been emphasizing the need for quality assurance of herbal products, including testing for inadvertent contamination. The authors conducted a quality-assurance evaluation of residual organochlorine pesticides in some popular brands of Indian herbal teas. Organochlorine pesticide residue build-up from agricultural or storage practices was estimated with gas-liquid chromatography. The results revealed scant presence of dichlorodiphenyltrichloroethane (DDT) or its metabolites; endosulfan--a highly toxic pesticide--was absent in all 8 brands of herbal teas studied. Hexachlorocyclohexane isomers were detected in 2 samples, but levels were below the permissible limit for pesticide residue in foods, as promulgated by the Codex Alimentarius Commission. The authors believe that all herbal preparations should be checked for toxic chemical residues to allay consumer fears of exposure to known neurotoxicant pesticides and to aid in promoting global acceptance of these products.

Gold mining can release contaminants, including mercury, into the environment, and may increase exposure to naturally occurring elements such as arsenic. The authors investigated environmental and human tissue concentrations of arsenic and mercury in the gold mining town of Siuna, Nicaragua. The study involved 49 randomly selected households in Siuna, from whom a questionnaire along with environmental and fingernail samples were collected. Environmental samples indicated that mercury concentrations in drinking water, although generally low, were higher near the mine site. Arsenic concentrations were elevated in water and soil samples, but their distribution was unrelated to the mining site. Mercury concentrations in fingernail samples were correlated with residential proximity to the mine, drinking water concentrations, occupation, and, among children, with soil concentrations. Fingernail arsenic concentrations correlated with drinking water concentrations among adults who consumed higher levels, and with soil concentrations among children. Fingernail analysis helped to identify differential exposure pathways in children and adults. Mercury and arsenic uptake via soil exposure in children warrants further consideration.

The authors assessed the acute effects of exposure to noise on systolic and diastolic blood pressure, and heart rate, among 46 workers in a midwestern auto assembly plant. Workers wore ambulatory blood pressure monitors and personal noise dosimeters during one work shift. After adjustment for covariates of cardiovascular function, systolic and diastolic blood pressure, along with heart rate, were shown to be significantly positively associated with noise exposure. Although the long-term effect of these associations is not known, results from other studies suggest that they may be harmful. Replication of this study with a larger number of subjects, monitored for several days and in a variety of work settings, is recommended to verify these findings. The results of this and other studies imply that reducing acute noise exposure reduces cardiovascular stress.

The authors surveyed agricultural production methods and pesticide use among subsistence farmers (campesinos) in 4 rural communities of Campeche, Mexico. Self-reports of symptoms of poisoning resulting from occupational pesticide exposure were elicited by questionnaire (N = 121), and acetylcholinesterase (AChE) activity during insecticide use was evaluated from blood samples (N = 127). In individuals from 2 of the 4 communities, AChE activity was significantly lower (p < 0.05) than the mean of activity determined for individuals in a reference group. Results of this study show that erythrocyte AChE inhibition provides a good biomarker of exposure to organophosphate pesticides in field studies with human populations. Carbamates, particularly carbofuran, seem to be more associated with exuberant and diversified symptomatology of pesticide exposure than organophosphates. Studies in field communities where both carbamates and organophosphates are suspected to exist should include blood AChE determinations, symptomatology surveys, and socioeconomic questionnaires. The authors recommend that the Mexican National Health Ministry authorities specify additional provisions regarding the use of protective equipment and the adoption of other safety practices during field work, increase information campaigns about the risks of pesticide use and the value of safety practices, and increase programs of medical monitoring and assistance for rural communities dealing with pesticides.

The vanilloid receptor (TRPV1 or VR1), widely distributed in the central and peripheral nervous system, is activated by a broad range of chemicals similar to those implicated in Multiple Chemical Sensitivity (MCS) Syndrome. The vanilloid receptor is reportedly hyperresponsive in MCS and can increase nitric oxide levels and stimulate N-methyl-D-aspartate (NMDA) receptor activity, both of which are important features in the previously proposed central role of nitric oxide and NMDA receptors in MCS. Vanilloid receptor activity is markedly altered by multiple mechanisms, possibly providing an explanation for the increased activity in MCS and symptom masking by previous chemical exposure. Activation of this receptor by certain mycotoxins may account for some cases of sick building syndrome, a frequent precursor of MCS. Twelve types of evidence implicate the vanilloid receptor as the major target of chemicals, including volatile organic solvents (but not pesticides) in MCS.

In the absence of a "soil model" on arsenic bioavailability, many investigators conducting baseline risk assessments of arsenic-enriched sites have assumed that all arsenic present in the soil is bioavailable. This assumption overestimates actual human health risk because various geochemical forms of arsenic are stable, or insoluble, in human digestive juices. The authors conducted a laboratory incubation study to analyze the in vitro bioavailability of arsenic in soils as a function of soil properties. Four different soil types were selected on the basis of their potential differences with respect to arsenic reactivity. Each soil was amended with sodium arsenite at a rate representative of a routine 1-yr application of arsenical pesticide in an agricultural system. The soils were incubated for 1 yr, after which the authors measured soil-specific total and bioavailable arsenic concentrations. Results demonstrated that soil physicochemical properties significantly affect arsenic bioavailability, and hence estimates of cancer risk, which in turn affect site cleanup cost projections.

In this study, the authors investigated the short-term (i.e., 1-yr) health effects of low-level occupational and personal exposure to ionizing radiation in a hospital setting. Thyroid function, lung function, platelet count, and leukocyte classification were obtained for 142 ionizing radiation operators. In addition, individual exposure doses were measured. The mean annual cumulative dose in 25 exposed subjects was 6.0 +/- 10.1 millisieverts. The highest exposure ratio among 20 of 41 (49%) radioisotope operators was significantly higher than for other ionizing radiation workers. Abnormal leukocyte counts occurred in 26% of radio-diagnosis operators and 30% of radioisotope operators, compared with 15% for other potentially exposed operators. No significant relative risk was found in subjects with above-background exposures. However, the highly exposed population experienced elevations in thyroid stimulating hormone (adjusted odds ratio [ORa = 2.0; T3 [OR = 1.7]); mononuclear leukocytes (ORa = 2.4); and basophilic leukocytes (ORa = 2.0). Although the authors failed to find short-term health effects in hospital operators exposed annually to less than 6.0 millisieverts of ionizing radiation, additional protection would certainly be prudent for these operators.