[Quality control of data produced in biological population surveillance studies on the risk of environmental lead poisoning]. / Il controllo di qualità dei dati prodotti nelle indagini per la sorveglianza biologica della popolazione contro il rischio dell'inquinamento ambientale da piombo.

The biological surveys of the general population against the risk of lead intoxication carried out in Italy--in accomplishment both of the EEC directive EEC 77/312 and the Presidential Decree 496/1982--have been always conceived as multicentric activities. Therefore, starting from the first campaign carried out in 1979, strict quality control procedures have been adopted. In brief, each participant laboratory used internal quality control samples and took part in external quality assessment exercises. In addition, ten percent of the blood samples collected during the campaign were analyzed as blind duplicate by both participating laboratories and a reference laboratory. In this paper the quality control procedures adopted will be presented and discussed in detail together with the quality of results obtained in each campaign.

[Lead exposure: risk evaluation for the general Italian population in 1990]. / Esposizione al piombo: valutazione del rischio per la popolazione generale italiana negli anni '90.

The second Italian campaign for the biological surveillance of the general population against the risk of lead intoxication has been carried out according to the regulations contained in the Presidential Decree DPR 496/82. The investigations of the second campaign--based on the measurement of blood lead levels (PbB)--have been carried out mainly between 1992 and 1996 by various operating centers in some Italian regions. A work group from the Istituto Superiore di Sanità (Italian National Institute of Health) coordinated the activity of the various centers and organised an appropriate quality control program to guarantee the quality of the analytical data collected. A total of 7749 non exposed subjects (4346 females and 3403 males) has been examined, 1170 of which (559 females and 611 males) were under 15 years of age. The median PbB was, for adults, 86 micrograms/l in males and 53.5 micrograms/l in females. As for subjects under the age of 15, PbB levels were 50 micrograms/l and 43 micrograms/l in males and females, respectively. Our investigation confirms the correlation between blood lead levels, wine, and cigarette smoking. The comparison with the results of previous investigations shows a reduction between 40% and 50% of PbB in the general Italian population during the 1985-96 period. It should be pointed out that in certain areas more than 5% of subjects under 15 years of age had PbB exceeding the level (100 micrograms/l) considered safe for avoiding irreversible injury to the central nervous system.

[Evaluation of environmental lead exposure in Latium: 2d DPR 496/82 campaign]. / Valutazione dell'esposizione ambientale al piombo nel Lazio: seconda campagna DPR 496/82.

In the Latium region, according to the regulations contained in the presidential decree DPR 496/82, the investigations of the second campaign--based on the measurement of blood lead levels (PbB)--have been carried out between 1992 and 1994. Three samples of subjects were examined: adult subjects (33 males and 628 females) living in Priverno, a small town in the South of the Latium region; adults subjects living in the Rome area (81 males and 168 females; subjects under the age of 15 (65 males and 54 females) living in the Rome area. Concerning Priverno, the median PbB was 70 micrograms/l in males and 40 micrograms/l in females; in Rome 66 micrograms/l and 42 micrograms/ l in males and females, respectively. In subjects under the age of 15, PbB levels were 40.5 micrograms/l and 35.5 micrograms/l in males and females, respectively. As for adults PbB levels were significantly higher in female than in male subjects and in subjects aged 41 years and over in comparison with subjects aged 15-40 years. PbB levels were significantly higher in wine drinkers in comparison with non-drinkers. The difference between smokers and non smokers was significant only in female subjects living in Rome. In multiple regression analysis the association of PbB with age, sex, alcohol consumption and smoking habit were confirmed, and a positive relation between PbB and the condition of being living in Rome. As for Rome, the comparison with the results of previous investigations shows a reduction between 50% and 60% of PbB during the 1985-1992 period.

The Italian external quality assessment scheme for trace element analysis in body fluids.

We describe the operative procedures of the Italian external quality assessment scheme (EQAS) for the determination of trace elements in body fluids. The aims of the scheme are both the education of participants and the continuous development and optimization of procedures for collaborative EQA trials. Participation is free of charge. Interlaboratory exercises for EQA are organised every three or four months for the determination of cadmium and lead in blood; aluminium, copper, selenium and zinc in serum; chromium and nickel in urine. Freeze-dried control materials are prepared in the laboratory from animal blood or human urine. In each trial, each participant receives from six to eight samples, chosen from among the pools selected for that occasion using a randomised strategy and including unknown duplicate specimens. Laboratory performances are evaluated on the basis of proximity to target values, differences in results for duplicate samples and comparison with established acceptability limits. The development of dedicated software for the bidirectional transmission of data between the organising centre and the peripheral laboratory gives the participants the chance to verify immediately the quality of their results and take action without delay, if needed.

Prospects of harmonisation of European external quality assessment schemes in occupational and environmental laboratory medicine.

Since 1979, twelve external quality assessment schemes (EQAS) in occupational and environmental laboratory medicine (OELM) have been developed in nine European countries. These schemes cover a broad range of analytes and matrices and have developed differing procedures for the evaluation of laboratories' performances. Collaboration among EQAS in OELM and harmonisation of methods for evaluation of laboratory performance would be advantageous to cope with the demand for assessment of quality of analytical results for an increasing number of analytes and the need to guarantee comparability and consistency of conclusions on health and regulatory issues in different countries and at an international level. This paper compares the different features of the existing EQAS, to highlight critical points for further discussions, and to make some suggestions for possible further collaboration.

[Quality control for trace elements in occupational and environmental medicine]. / Controllo di qualità per gli elementi in traccia in medicina occupazionale ed ambientale.

The adoption of procedures warranting the quality of the results obtained in the laboratory is of the utmost importance, whatever the reason these analyses are required for. We discuss some of the fundamentals of quality assurance, as recommended by the International Federation of Clinical Chemistry, IFCC. Procedures for the preparation of control and calibration materials, the evaluation of analytical methods and the assessment of laboratory performance by means of internal quality control procedures, including control charts, are reviewed. Finally, we report the organisation and the strategies use in programmes for external quality assurance for the determination of trace elements in biological fluids.

Organization and results of a pilot scheme for external quality assessment in clinical chemistry carried out in the Latium region, Italy.

The results of an external quality assessment scheme (EQAS), carried out in the Latium region between October 1987 and December 1988, are reported. Ninety-four laboratories, both public and private, took part in the scheme. Aim of the scheme was to estimate the reliability of the clinical chemistry services in this region. The participating laboratories received eight control samples for EQA, every two months. The analytes to be determined in each sample were: glucose (GLU), urea (UR), total protein (TP), uric acid (UA), creatinine (CR), bilirubin (BIL), cholesterol (CHO), triglycerides (TRI), sodium (Na), potassium (K), calcium (Ca), aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CPK), gamma glutamyl transferase (GGT), and alkaline phosphatase (ALP). Global laboratory performances were evaluated in terms of interlaboratory precision, accuracy--as deviation per cent from the target values and coefficient of variation (CV)--and percentage of results within pre-set acceptability limits. The deviations were reasonably low, whereas the CVs were rather high. The percentage of acceptable results was lower than 50% for the analytes urea, calcium, uric acid, creatine kinase and alkaline phosphatase. The performance of the examined laboratories was worse than those obtained in other regional and national EQAS, both in terms of CVs and percentage of acceptable results.

Quality assurance in the determination of metals in clinical chemistry and toxicology: the METOS project. Metalli Tossici.

National external quality assessment schemes (EQAS) for the determination of trace elements in blood (Al, Cd, Cu, Pb, Zn) have been promoted in Italy since 1983. They were organized by a working group of the Istituto Superiore di Sanità and known as "METOS (Metalli Tossici, toxic metals) project". The organization of the schemes included the preparation of suitable control materials by the promoting centre and the elaboration of valuable strategies of sample distribution, treatment of data and evaluation of results, that could be applied even to a small number of participants. The procedures used and the results obtained in ten years of activity of the METOS project are reported. Within the framework of the programme some information has been obtained, confirming the validity of the procedures used for sample preparation, sample distribution and evaluation of laboratories performance.

National and regional regulations on minimal requirements, quality control and accreditation for clinical laboratories in Italy.

The national law concerning minimal requirements and quality control for clinical laboratories, dating back to 1984, is a decree of the President of the Council of Ministries (DPCM). Minimal requirements are established regarding general organization of the laboratory, instrumental equipment's, the personnel, the list of analytical tests, the director of the laboratory and its responsibilities, and quality control systems. Concerning regional legislation, since 1978 eighteen regions and the two autonomous provinces of Trento and Bolzano have issued--in the matter of minimal requirements and quality control for clinical laboratories, and point of specimen collection--laws, decrees, resolutions, deliberations, regulations and circulars that have determined in Italy a disparity of situations and a non-homogeneous regulation. The prerogative of the regions has been recently confirmed (laws 502/1992 and 517/1993): the introduction of appropriate procedure for the accreditation of both public and private services who want to operate within the National Health Service is defined as impelling. The homologation to operate may be acquired if the structure or the service actually has the instrumental, technical, and professional endowment corresponding to criteria established on a national basis. The national legislator deemed it necessary to establish a coordination on a national basis to uniform and standardize protocols, operating procedures, and methods of evaluations. The Istituto Superiore di Sanità (ISS) can have a key role in this coordination activity, mainly concerning technical/scientific aspects.(ABSTRACT TRUNCATED AT 250 WORDS)

Association of blood lead to blood pressure in men aged 55 to 75 years: effect of selected social and biochemical confounders. NFR Study Group.

The association of blood lead (B-Pb) concentration to blood pressure was investigated in men aged 55 to 75 years living in the Rome area, who had no history of exposure to lead in the workplace and who participated between 1989 and 1990 in an epidemiologic survey for coronary heart disease (New Risk Factor Project). Of the 1856 individuals eligible for the study, 59 were excluded from analyses because not all relevant data were available; and 478 were excluded because they were treated for hypertension. In the remaining subjects (n = 1319) the median B-Pb concentration was 113 micrograms/l (range: 40-442 micrograms/l). Systolic blood pressure (SBP) averaged 140 +/- 18 (standard deviation) mm Hg (range 98-220) and diastolic blood pressure (DBP) 84 +/- 9 mm Hg (range 56-118). Median B-Pb values increased significantly from 111 micrograms/l in subjects with normal blood pressure (n = 668) to 113.5 micrograms/l in subjects with borderline high blood pressure (n = 373) and to 120 micrograms/l in subjects with increased blood pressure (n = 278). After log-normal conversion of B-Pb, the linear correlation coefficient between In[B-Pb(ug/l)] and both SBP and DBP was statistically significant (r = 0.1332, p < 0.001 and r = 0.0737, p = 0.007, respectively). The linear regression coefficient was 6.8 mm Hg/In(micrograms/l) for SBP and 1.8 mm Hg/In(microgram/l) for DBP. Multiple regression analyses revealed that, after correction for body mass index (BMI), age, heart rate, skinfold thickness, serum lipids, and glucose levels; blood lead was still a significant predictor of increased SBP and DBP.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum triglycerides in the prediction of coronary artery disease (an Italian experience).

An occupational group living in Rome and composed of 3,007 men aged 46 to 65 years who were free from previous major coronary events was screened for a number of coronary risk factors and then followed up for 10 years. In all, 107 coronary deaths occurred in 10 years. There was a positive relation between coronary death rate and increasing levels of triglycerides, but the difference between the extreme quintile classes was not any more significant after adjustment for cholesterol levels. A cross-classification involving low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol and triglyceride levels showed a higher coronary artery disease (CAD) mortality in subjects with a higher LDL cholesterol/HDL cholesterol ratio and higher triglycerides. However, the excess risk in this subgroup was largely explained by the mean levels of total cholesterol. The multivariate proportional-hazards Cox model with coronary deaths as the end point, and age and triglycerides as predictors, produced a significant coefficient for triglycerides that became nonsignificant when other lipids alone or in combination (total, HDL and LDL cholesterol and some of their ratio) were fed into the model as further covariates. It is concluded that there is no evidence of an independent role of triglycerides in the prediction of coronary deaths.

Association of serum copper and zinc with serum electrolytes and with selected risk factors for cardiovascular disease in men aged 55-75 years. NFR Study Group.

Serum Cu (S-Cu) and Zn (S-Zn) levels were determined in 1468 out of 1856 male subjects aged 55-75 years living in the Rome area who participated, between 1989 and 1990, in the second examination in an epidemiological (New Risk Factors) survey. Mean S-Cu and S-Zn concentrations were 15.98 mumol/l (mean +/- 2SD: 10.38-21.58 +/- mumol/l) and 13.69 mumol/l (mean +/- 2SD: 8.94-18.44 mumol/l), respectively. S-Cu levels were directly related to serum calcium levels (S-Ca), serum magnesium levels (S-Mg), daily cigarette consumption, total cholesterol and age (years). S-Zn levels were directly related to S-Ca, S-Mg and cholesterol and inversely related to age. A weak inverse linear relationship existed between S-Zn and S-Cu. After adjustment for body mass index (BMI), smoking habit, alcohol consumption and blood biochemistry in a multiple linear regression model, the relationship of S-Cu (direct) and S-Zn (inverse) to age remained statistically significant.

The quality of analytical determinations of copper and zinc in serum. A collaborative study in a sample of Italian laboratories.

An external quality assurance scheme for Cu and Zn analysis in serum was carried out in Italy between 1989 and 1990. It included: preparation of control materials by the organizing centre; distribution of control samples to the participants according to a random selection; elaboration of results and evaluation of laboratory performance. Inter-laboratory variability was 16.9% and 16.4%, at concentrations of 0.94 and 1.08 mg/l, for Cu and Zn, respectively. Laboratory performance in terms of percentage of results within the limits of acceptability, improved for Cu, but not for Zn analysis.

Association of selected social, environmental and constitutional factors to blood lead levels in men aged 55-75 years.

Blood lead (B-Pb) levels were determined in 1802 out of 1856 non-occupationally exposed men aged 55-75 years living in the Rome area who participated, between 1989 and 1990, in an epidemiological survey for coronary heart disease (New Risk Factors Project). The median B-Pb level was 113 micrograms/l (10th-90th centiles: 74-180 micrograms/l) and only 0.7 per cent (n = 14) of the subjects had B-Pb values higher than 300 micrograms/l. B-Pb levels were significantly and positively associated to alcohol consumption. Moderate and heavy drinkers had median B-Pb level of 143 micrograms/l (10th-90th centiles: 92-233) and 165 micrograms/l (10th-90th centiles: 102-285) respectively, whereas non-drinkers had a median B-Pb level of 96 micrograms/l (10th-90th centiles: 66-143). The influence of smoking habits was less relevant. Subjects who never smoked and subjects smoking more than 20 cigarettes daily had median B-Pb levels of 103 and 133 micrograms/l, respectively. Individuals classified as habitual car-drivers had slightly higher Pb levels than non-drivers. Subjects classified as manual workers had higher B-Pb levels in comparison with non-manual workers and retired subjects. B-Pb levels were directly related to HDL-cholesterol (HDL-C, r = 0.2252) and gamma-glutamyltransferase (gamma-GT, r = 0.2207) serum levels. The alleged alcohol consumption was more related to B-Pb level (r = 0.3848) than to serum level of HDL-C (r = 0.2474) or gamma-GT (r = 0.2469). A significant correlation (r = 0.2409) also existed between B-Pb and blood cadmium levels (B-Cd). Subjects with a low Gaensler ratio, an index of respiratory function, had higher B-Pb levels. In multiple regression analyses alcohol intake was the most important predictor of B-Pb level, explaining more (14.27%) of the total variance than did B-Cd (4.98%), HDL-C (1.89%), driving habits (1.46%), gamma-GT (1.09%), skinfold thickness (0.96%), and Gaensler index (0.38%). The risk ratio of having B-Pb level higher than 180 micrograms/l (90th centile of B-Pb distribution in our subjects) was 5.3 (95% CI: 2.7-10.4) for drinkers versus non-drinkers and 1.9 (95% CI: 1.2-3.1) for current smokers versus subjects who had never smoked. B-Pb was, at least in our subjects, a more specific and sensitive objective index of alcohol consumption than gamma-GT and HDL-C.(ABSTRACT TRUNCATED AT 400 WORDS)

Serum ascorbic acid levels in men aged 55-75 years: association to selected social factors and biochemical parameters.

Serum ascorbic acid (SAA) levels were determined in 500 subjects aged 55-75 years participating in the New Risk Factors (NRF) Survey between March and December 1990. In the total sample mean concentration of SAA was 8.75 mg/1 (95% confidence interval: 8.41-9.20). SAA levels of 2 mg/l or less (severe hypovitaminosis C) were found in 19 subjects (3.8%). A further 9.6% of subjects (n=48) has SAA levels between 2 and 4 mg/l (marginal hypovitaminosis C). Subjects with hypovitaminosis C reported a significantly higher daily cigarette consumption and had higher blood lead (B-Pb) and blood cadmium (B-Cd) levels. An Inverse relationship was found between SAA levels and smoking status, body mass index (BMI) and B-Pb. Among current smokers aged 55-65 years the prevalence of hypovitaminosis C was not significantly higher than in non smokers (chi(2) was 2.4 for severe and 4.7 for marginal hypovitaminosis C, respectively). On the contrary, in subjects aged 66-75 years the occurrence of hypovitaminosis C was significantly higher in smokers than in non-smokers (chi(2) was 6.6 for severe and 10.3 for marginal hypovitaminosis C. respectively).

Serum selenium and precursors of cardiovascular risk factors in adolescents.

The aim of this study was to determine, in a population of Italian adolescents, the association of serum selenium levels with precursors of biochemical and anthropometric variables known as being among the major risk factors for cardiovascular diseases in the adult population. The following measurements were taken in a school sample of 627 adolescents (aged 12-13 years); serum selenium, total cholesterol, high density lipoprotein cholesterol, non-HDL cholesterol, height, weight, body mass index, systolic blood pressure and diastolic blood pressure. The serum selenium levels were slightly higher in males (83.1 +/- 10.1 micrograms/l) than in females (81.7 +/- 11.0 micrograms/l), but the difference was not statistically significant. Serum selenium was positively correlated with total cholesterol, diastolic blood pressure and HDL cholesterol in both sexes; moreover it was positively correlated with non-HDL cholesterol and negatively correlated with height in males only.

Changes of serum selenium and serum cholesterol in children during sexual maturation.

We investigated the relationship of the degree of sexual maturation to serum selenium and serum cholesterol fractions in a population of Italian children. The following measurements were taken in 109 immature and 108 mature children of both sexes (aged 12 and 13a): serum selenium, total cholesterol, high density lipoprotein cholesterol, height, weight and degree of sexual maturation. Considerable differences were found in the two sexes at the end of maturation, with boys showing a significant decrease in serum selenium, HDL and non-HDL serum cholesterol levels. All variables, except height and weight, remained relatively constant in girls. These data indicate significant changes of serum selenium and serum cholesterol patterns during puberty, at least in boys, suggesting an involvement of sexual hormones in regulating serum selenium levels.

Increased serum selenium levels in patients under corticosteroid treatment.

The normal serum and tissue levels of many micronutrients are remarkably affected by the therapeutical administration of several substances. In the present study, we have evaluated the modifications of serum selenium levels in different groups of patients under corticosteroid treatment. Such therapy was significantly associated with increased serum selenium levels, with a dose-dependent relationship in subjects treated with methylprednisolone. The reasons for this association are unknown. However, a reduced renal excretion of selenium, due to the mineralcorticoid activity of the corticosteroids, can be inferred.

High density lipoprotein cholesterol distribution and predictive power in some Italian populations studies.

Nine Italian population samples, for a total of 12,365 males and 8,043 females aged 11 to 84, were examined. The age and sex distribution of HDL-cholesterol levels were calculated for studying its relationship with major cardiovascular risk factors, and for estimating its predictive power on coronary events and on all causes of mortality. Mean values of HDL-cholesterol in the pool of the samples ranged, according to different age groups, from 46.4 to 56.8 mg/dl in males and from 53.7 to 55.8 mg/dl in females. The linear correlation coefficients between HDL-cholesterol and 10 risk factors did not show high levels except those with triglycerides in men aged 20-34 (-0.33) and 35-64 (-0.34). Using the multiple linear regression model the levels of HDL-cholesterol were estimated as a function of the 10 risk factors solving 4 equations (for males, females and for two age groups, 20-34 and 35-64). The factors showing significant coefficients were body mass index (negative), triglycerides (negative), cigarette smoking (negative), alcohol consumption (positive), physical activity (positive), and non-HDL-cholesterol (negative). The Cox model was used for the prediction of coronary death and all causes of death and the logistic function for the prediction of coronary incidence in two of the studies on men aged 46-65 (6 year follow-up) and aged 60-79 (5 year follow-up), and including 5 other factors as possible confounders. Only the univariate prediction of coronary deaths in one study (men aged 46-65) provided a significant coefficient for HDL-cholesterol (t = -2.7624).