Non-occupational lead exposure and hypertension in northern Italy.

BACKGROUND: Previous research has addressed the issue that low-level blood lead concentration could be associated with an increased risk of hypertension. METHODS: This paper examines the cross-sectional association between blood lead and hypertension in 630 adult males not employed in activities characterized by specific exposure to lead and living in two Northern Italian cities (Verona and Brescia). The participants, aged 26-69 years, constituted a random sample of the patients in the practice of a general practitioner (Verona) and of regular blood donors (Brescia). Logistic regression analysis was used to evaluate the effects of selected variables (blood lead, blood cadmium, zinc erythroprotoporphyrin, haemoglobin, whole blood viscosity, age, body mass index, smoking habits and alcohol consumption) on the probability of being hypertensive. RESULTS: The blood lead concentration (range: 4.3-46.9 micrograms/dl; median: 14.8 micrograms/dl) was very similar in the two samples, whereas the prevalence of hypertension was significantly higher in the Verona sample than in the Brescia sample (20.4% versus 8.3%). Hypertensive subjects showed significantly higher blood lead levels than normotensive ones. In a preliminary (univariate) analysis blood lead levels, body mass index (BMI) and age were each significantly related to the prevalence of hypertension. After adjusting for age and/or BMI, statistical significance of the relationship between blood lead and hypertension was lost.CONCLUSIONS. The present study showed that blood lead is weakly related to hypertension in non-occupationally exposed men. The statistical significance of this association disappeared when age and BMI were used to make adjustments.

Is hypertension a confounding factor in the assessment of blood lead reference values?

In order to evaluate whether hypertension can be considered as a confounding factor in the setting up of reference values for blood lead, we examined the results of a cross sectional study which evaluated the relationship between lead in blood and hypertension in a sample of 254 males and 271 females of a general population not occupationally exposed to lead. The statistical analysis and in particular the multiple logistic regression showed that, even if some well-known confounding factors such as age, sex, overweight, smoking and alcohol are taken into account, blood lead levels are well correlated with hypertension. The results suggest that even modest lead absorption is able to influence the probability of being hypertensive. The relationship between blood lead and hypertension and their relationship with the main confounding factors involved in the determination of reference values of metals in blood are discussed.

Urinary thallium: critical problems, reference values and preliminary results of an investigation in workers with suspected industrial exposure.

Using a sensitive ETA ASS method, urinary thallium (Tl-U) has been measured in a group of non-exposed individuals and in two groups of workers with suspected industrial exposure. In non-exposed subjects (72 healthy males aged 41 +/- 11 years) the Tl-U mean value was 0.22 mu/l (range 0.05-0.61). Significantly higher values were found in two groups of workers (30 and 21 subjects) employed in two cement factories and two cast iron foundries (mean Tl-U value: 0.38 and 0.33 mu/l, respectively; range 0.06-1.2). Thallium has been determined in coal, raw materials and, in one factory, also in environmental samples, but no detectable levels were found. The analytical problems connected to urinary thallium determination and the preliminary results of biological monitoring in non-exposed individuals and in workers are discussed.

Urinary chromium levels in subjects living in two north Italy regions.

The concentration of total urinary chromium (Cr-U) in two different groups of healthy occupationally non-exposed subjects living in the Italian regions of Lombardia and Veneto has been determined using an ETA-AAS direct method. The age, sex, residence and smoking habits were correlated with CrU excretion. The mean CrU value found in subjects living in Lombardia (n = 310, males 170 and females 140) was 0.59 + 0.26 microgram/l (range 0.08 - 2.10); in Veneto subjects (n = 238, males 187 and females 51) the mean value was 0.52 +/- 0.31 microgram/l (range 0.05 - 1.90). A significative difference between male and female values and a decrease of CrU levels with age increasing have been evidenced in both groups. Smoking habits seem to influence metal urinary levels while, on the other hand, no influence of living sites was observed. Some analytical problems of ETA-AAS Cr determination systems are discussed and "normal" CrU values measured in this study are compared with data reported in the literature.

Tentative reference values for some elements in broncho-alveolar lavage fluid.

The concentrations of Fe, Mn, Pb and Cr have been determined in broncho-alveolar lavage (BAL) fluid of 25 subjects without occupational or abnormal environmental exposure to metals, using the AAS method. The numerous factors which can interfere with the results in pre-analytical and in analytical phases are stressed. Metals concentrations in BAL are expressed in micrograms/l. They were not correlated with the volume of fluid recovered, the total cells, alveolar macrophages and erythrocytes. The results were not modified by stratification considering age and sex. Iron concentrations were higher than others, probably due to higher environmental exposure and partly to its essential role in humans. The diagnostic significance of element determination in BAL fluid and the relationship with exposure and lung load is discussed.

[Guidelines for assessment and management of risks caused by benzene for workers at gas stations]. / Linee guida per la valutazione e la gestione dei rischi da benzine per la salute dei lavoratori addetti alle stazioni di servizio carburanti.

The European regulations classify gasoline as "carcinogenic agent" because of its content of benzene (> 0.1%). Consequently the preventive and protective actions towards the petrol station attendants prescribe, before all, the elimination of the agent or the reduction of the exposure and the risk to the minimum. Well known are currently a series of preventive measures able to produce appreciable reduction of the risk: reduction of the benzene content of gasoline, vapor recovery systems, self-areas or do-it-yourself, specific procedures for working. Exposure assessment is an essential step in order to establish the need for further preventive measure and to verify their efficacy. The exposure levels to gasoline of the petrol station attendants can be influenced by a variety of factors other than benzene air concentrations and therefore biological monitoring can give some sensible advantage in respect to air monitoring. Dosage of benzene in expired air, in urine, or in blood give a very good estimation of the exposure to benzene but they are not test largely practicable today, because analytical, economical, organizational reasons. Recent studies suggest that the dosage in urine of trans,trans muconic acid (ttMA) or phenil mercapturic acid can be useful biomarkers of recent exposure, even at low levels of exposure such as in filling stations. Exposure conditions to gasoline vapors in filling stations are rapidly changing thanks to some technological innovations and legal restrictions and the exposure levels are much below the occupational air standards, Toxicological and epidemiological data (although not yet conclusive at low doses) suggest to carry out however health and epidemiological surveillance programs for the working population. A program for the health surveillance and biological monitoring is here proposed: a clinical examination, integrated with haematological tests and biological monitoring tests, must be carried out in pre-employment and subsequently repeated yearly in the highest exposure conditions. When the exposure levels should decrease the examinations could be carried out every two years.

[The prospects for the appearance of pleural mesothelioma in Italy]. / Prospettive di comparsa del mesotelioma pleurico in Italia.

The mortality data of Italian males and females due to malignant tumour of the pleura, collected over a period of 7 years, from 1976 to 1985, showed a continuous, rectilinear type, increase. The increase in the quantity of asbestos that was processed from 1945 to 1979 was also rectilinear. On the basis of the well known relationship between asbestos and mortality due to mesothelioma, an extremely high correlation coefficient was obtained between quantity of asbestos processed per year and number of deaths due to malignant tumour of the pleura 25 years later. Extrapolating to the year 2000 on the basis of this relationship, it can be foreseen that at that time the deaths due to malignant tumour of the pleura in Italy will be about 1200 per year. It is recommended to apply a correction factor to this figure in order to obtain the number of true cases of mesothelioma, which are probably about 70% of the deaths attributed to tumour of the pleura.

[Exposure to silicon carbide fibers in the production of carborundum]. / Esposizione a fibre di carburo di silicio nella produzione del carborundum.

Recent reports have shown that not only silicon carbide dusts but also fibres are liberated into the working environment during the various phases of silicon carbide production (using Acheson furnaces), thus creating a further potential health hazard. An environmental hygiene survey was conducted in a silicon carbide production plant with the aim of quantifying airborne dusts and fibres. Although dust levels were below 50% of the TLV, high concentrations of fibres were observed (analyzed via optical microscopy using the criteria for asbestos fibres), which in some locations reached levels of 2000 fibres/litre with means (GM) between 100 and 780 fibres/litre according to department. These results are assessed in the light of the growing interest of researchers in the experimental effects of silicon carbide fibres.

[The exposure to tobacco smoke of the employees of a telephone company]. / Esposizione al fumo di tabacco degli impiegati di un'azienda telefonica.

Smoking habits were studied in a group of employees of a telephone company. The smokers were 34% of the subjects interviewed. The non-smokers said that they were bothered by other people smoking everywhere and also to a considerable extent at the workplace. Differences between smokers and non-smokers and between exposed and non-exposed non-smokers were studied by measuring expired CO and urinary cotinine. An expired CO concentration of 10 ppm discriminated between smokers and non-smokers. A mean urinary cotinine concentration of about 16 ng/mg was found in the exposed non-smokers, corresponding to the direct smoking of 1/10 of a cigarette per day. The search for the metabolic phenotype of destromethorphane, which was taken as an indicator of susceptibility to contract lung cancer due to IPA, showed that there were no differences between smokers and non-smokers since the rapid metabolizers, and therefore subjects potentially exposed to risk of lung cancer due to tobacco smoke, prevailed in both groups.

[Pesticide immunotoxicity]. / Immunotossicità da pesticidi.

Pesticides have been reported as altering immune functions in animals and man. The authors review published data from which it emerges that pesticide exposure is often associated with depressed humoral and cellular responses in mammals. The immunomodulating effects are affected by the route of administration and can also occur without general toxic effects, with a clear dose-effect correlation and for different dose levels. Immunotoxicity has also been investigated in workers occupationally exposed to pesticides: many kinds of effects are described, since many immunotoxicants have multiple effects on immune functions but the authors emphasize the importance of further studies carried out in workplace situations where exposure levels can be more accurately measured.

Carbon disulfide in blood: a method for storing and analysing samples.

Concentrations of free and acid-labile carbon disulfide in human blood were determined by gas chromatography mass-spectrometry. Carbon disulfide was measured in the blood of 62 subjects not occupationally exposed to the solvent, and in 27 subjects treated with disulfiram (which is partially biotransformed into carbon disulfide). In blood, a small part of carbon disulfide is free (it can be analysed without any blood treatment); most carbon disulfide is bound ("acid labile" carbon disulfide), and requires acid hydrolysis to become free and detectable. During the first phase of our study, stored samples of blood (storage at 4 degrees C for 15-40 days) were used. Later, we analysed fresh blood samples. A significant decrease in carbon disulfide was found in stored samples in comparison to fresh samples. During storage, free and acid-labile carbon disulfide in blood decreased respectively to 26% and 27% of the initial concentration within a month. In fresh samples, free carbon disulfide concentrations in blood showed a median of 139 ng/l in normal subjects. Acid-labile carbon disulfide concentrations were much higher (median 2743 ng/l). Free and acid-labile carbon disulfide in blood were closely correlated (r = 0.9358). Blood samples stored at -80 degrees C maintained a constant concentration of carbon disulfide over almost three weeks.

[The biological levels of chloroform in the general population]. / Livelli biologici di cloroformio nella popolazione generale.

The paper reports the results of determination, via gas chromatography and mass spectrometry, of chloroform in expired air, blood and urine of a group of non-occupationally exposed blood donors. Chloroform concentrations were also measured for each subject in the air of the environment where samples were taken.

[Effects of cigarette smoking on blood and alveolar air levels of benzene]. / Effetto del fumo di sigaretta sui livelli ematici ed alveolari di benzene.

Benzene was measured in blood and alveolar air of a group of 168 subjects, consisting of 34 chemical industry workers exposed to benzene and 134 definitely not occupationally exposed to benzene. A gas chromatographic method was used with mass spectrometry and cryogenic trap. The results of the biological measurements were compared with the environmental levels of benzene in the room where samples were taken and at the worksite during the previous day's shift. All environmental air samples showed measurable levels of benzene, which agrees with the observations of many authors, according to which benzene is a common pollutant also of the living and external environments. Benzene in blood measured on morning samples was correlated with the previous day's exposure. In the group of non-exposed, both blood and alveolar concentrations of benzene were significantly higher in the 68 smokers than in the 66 non-smokers and the biological levels of benzene were inversely correlated with the time that had elapsed since the last cigarette smoked. In the chemical workers, the high biological levels of benzene due to occupational exposure largely exceeded the variations in concentration due to cigarette smoking and cancelled out the differences between smokers and non-smokers. It can therefore be assumed that smoking was not influential and did not interfere with the interpretation of the results in the occupationally exposed workers. Lastly, cigarette smoking, as a cyclical and additional factors of exposure, seems to be responsible for the disturbance in the relationships between biological benzene levels and ubiquitous environmental pollution, a relationship that was only observable in non-smoking subjects not occupationally exposed, but not in the group of smokers.

Biological monitoring of fluctuating occupational exposures to styrene.

Nine workers occupationally exposed to styrene producing refrigerator lorries were analyzed. The styrene exposure was monitored 8 hours a day, for 5 days a week, for 1 week. We collected from workers a urine sample before and after each work shift. Moreover, alveolar air samples were obtained at the end of all work shifts. On Thursday afternoon and on Friday morning blood samples were taken from workers. The relationship between styrene exposure and biological data is reported and discussed. Alveolar, urinary and blood concentrations of styrene were comparable, suggesting similar kinetics. Biological styrene concentrations were significantly correlated with the mean daily environmental concentrations, but higher correlation coefficients were found with afternoon exposures. A narrow linear relationship between alveolar (Y) and urinary (X) styrene concentrations was found (Y = 0.359; r = 0.8579; n = 45; p less than 0.001). Urinary concentrations of mandelic acid (Y) confirmed a good relationship with the mean styrene exposure (X) (Y = 2.7 x +169; r = 0.4677 n = 45; p less than 0.01).

[Statistical aspects of the definition of reference values]. / Aspetti statistici della definizione dei valori di riferimento.

The criteria adopted in the study of reference values have a great influence on the statistical analysis of the data. To avoid a poor statistical treatment of the data, the scope of the study must be well defined: a study to establish reference values for a chemical in the body fluids of a population is not a survey to prove relations among variables and the chemical. In this latter case, criteria to select subjects and methods are different. Confusion between the two types of surveys can lead to poor results. Reference subjects must be selected with precision, using reproducible criteria. It can be suggested to pick-up subjects from a variety of sub-groups of the population. It must be used selection criteria strictly defined to exclude from the study groups of subjects having specified characteristics (patients, resident in contaminated-zone...). The use of partition criteria is useful to know the distribution of some characteristics in the population, or to describe reference values in particular subgroups. On the contrary, partition can not be used to study relationships. Particular attention must be payed in choosing number of strata and variable of partition. When a population is analysed for reference values, the choice of subjects and relevant variables must be made after consulting a statistician.