214 THE IMPACT OF ARRHYTHMIA ON PROGNOSIS IN HOSPITALIZED COVID-19 PATIENTS. A CARDIAC TELEMETRIC MONITORING STUDY

Background

Cardiovascular abnormalities have been largely reported in patients with COVID-19. Among these, myocardial injury and rhythm disorders represent one of the most important complications in patients affected by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection. Moreover, a poorer prognosis has been documented in COVID-19 patients when complicated by arrhythmias, independently by age and sex.

Objectives

The aims of the present study were to identify some of non-cardiac and cardiac comorbidities and some myocardial electrical features (including QT dispersion) associated with arrhythmia in hospitalized COVID-19 patients. Moreover, another objective was to contribute in analyzing the impact of arrhythmias on outcome in this setting of patients.

Methods

At admission, each patient underwent cardiac telemetry monitoring through entire hospitalization period. In all the subjects, laboratory analyses, standard 12-lead electrocardiogram (both at admission and on discharge), and lung imaging examination (by means of both ultrasound scans and computed tomography) were performed. Patients exhibiting arrhythmia during in-hospital period were divided into three groups: i, with brady-arrhythmias; ii, with tachy-arrhythmias; and, iii, with tachy- and brady-arrhythmias.

Results

Two-hundred patients completed the study (males, 123; mean age, 70.1 years); of these, 80 patients (40%) exhibited rhythm disorders on cardiac telemetry. Patients with arrhythmia resulted to be older (p<0.0001) than patients without arrhythmia. Moreover, patients with arrhythmia showed: i, greater number of comorbidities (p<0.0001); ii, higher values of creatinine (p=0.007), B-type natriuretic peptide (p<0.0001), troponin (p<0.0001), c-reactive protein (p=0.01), ferritin (p=0.001), d-dimer (p<0.0001), and procalcitonin (p=0.0008); iii, QT interval (p=0.002), QTc interval (p=0.04), and QTc dispersion (p=0.01); and, iiii, lower values of sodium (p=0.03), magnesium (p=0.04), glomerular filtration rate (p<0.0001), and hemoglobin (p=0.008) as compared to patients without arrhythmia. By comparing the three subgroups of patients, no significant differences were found. Multivariate analysis showed that age (OR=1.14 [95% CI: 1.07-1.22]; p=0.0004), coronary artery disease (OR=12.7 [95% CI: 2.38-68.01]; p=0.005), and circulating troponin (OR=1.05 [95% CI: 1.003-1.10]; p=0.04) represented risk factors independently associated with arrhythmia. By analyzing all-cause in-hospital mortality, it resulted a ∼forty-fold higher among patients with arrhythmia (OR=39.66 [95% CI: 5.20-302.51]; p=0.0004) when compared to patients without rhythm disorders.

Conclusion

In the present study, arrhythmias have been to be associated with ageing, coronary artery disease, subtle myocardial injury, hyperinflammatory status, coagulative unbalance, and abnormalities in myocardial electrical impulse propagation in patients affected by SARS-CoV-2 infection. In alignment with previous reports, the presence of arrhythmia seems to be associated with a worse in-hospital prognosis. Given its usefulness, routinary use of cardiac telemetric monitoring should be encouraged in COVID wards.

Platypnea-orthodeoxia syndrome in SARS-CoV-2 related ARDS: a case report

Platypnea-Orthodeoxia Syndrome (POS) is an often misdiagnosed clinical condition characterized by dyspnea and hypoxia in sitting or semi-sitting position, reversible in supine position. Although POS is typically associated with intracardiac shunts, it seems frequent also in SARS-CoV-2 related Acute Respiratory Distress Syndrome (ARDS). In fact, the prevalent involvement of the lung bases due to interstitial pneumonia can determine refractory positional hypoxemia, with marked desaturation in the sitting position and regression or improvement in the supine position, configuring the clinical picture of the POS. We present a clinical case of POS associated with acute respiratory distress from SARS-CoV-2 pneumonia in which refractory hypoxia would have required support by invasive mechanical ventilation if the syndrome had not been identified.

Predictors of in-hospital mortality of COVID-19 patients and the role of telemetry in an internal medicine ward during the third phase of the pandemic

OBJECTIVE

The first pandemic phase of COVID-19 in Italy was characterized by high in-hospital mortality ranging from 23% to 38%. During the third pandemic phase there has been an improvement in the management and treatment of COVID-19, so mortality and predictors may have changed. A prospective study was planned to identify predictors of mortality during the third pandemic phase.

PATIENTS AND METHODS

From 15 December 2020 to 15 May 2021, 208 patients were hospitalized (median age: 64 years; males: 58.6%); 83% had a median of 2 (IQR,1-4) comorbidities; pneumonia was present in 89.8%. Patients were monitored remotely for respiratory function and ECG trace for 24 hours/day. Management and treatment were done following the timing and dosage recommended by international guidelines.

RESULTS

79.2% of patients necessitated O2-therapy. ARDS was present in 46.1% of patients and 45.4% received non-invasive ventilation and 11.1% required ICU treatment. 38% developed arrhythmias which were identified early by telemetry and promptly treated. The in-hospital mortality rate was 10%. At multivariate analysis independent predictors of mortality were: older age (R-R for≥70 years: 5.44), number of comorbidities ≥3 (R-R 2.72), eGFR ≤60 ml/min (RR 2.91), high d-Dimer (R-R for≥1,000 ng/ml:7.53), and low PaO2/FiO2 (R-R for <200: 3.21).

CONCLUSIONS

Management and treatment adherence to recommendations, use of telemetry, and no overcrowding appear to reduce mortality. Advanced age, number of comorbidities, severe renal failure, high d-Dimer and low P/F remain predictors of poor outcome. The data help to identify current high-risk COVID-19 patients in whom management has yet to be optimized, who require the greatest therapeutic effort, and subjects in whom vaccination is mandatory.

Remdesivir plus dexamethasone versus dexamethasone alone for the treatment of COVID-19 patients requiring supplemental O2 therapy: a prospective controlled non-randomized study

Background

Remdesivir is an antiviral used to treat COVID-19 which improves some clinical outcomes. Dexamethasone has been shown to be effective in reducing mortality. It has been hypothesized that combination of these two drugs can improve mortality. We evaluated the effect of combination on mortality of COVID-19 patients requiring O₂ therapy.

Methods

A prospective quasi-experimental study, including two independent, sequential controlled cohorts, one received remdesivir-dexamethasone and the other dexamethasone alone, was designed. All COVID-19 patients requiring supplemental O₂ therapy were enrolled consecutively. The sample size to power mortality was a priori calculated. The primary endpoints were 30-day mortality and viral clearance differences. Secondary endpoints were differences in hospitalization times, improvement in respiratory failure (PO₂/FiO₂) and inflammatory indices (fibrinogen, CRP, neutrophil/lymphocyte ratio, D-Dimer). Kaplan-Meier curves and the log-rank test were used to evaluate significant differences in mortality between groups.

Results

151 COVID-19 patients were enrolled (remdesivir/dexamethasone group, 76 and dexamethasone alone,75). No differences in demographic, clinical and laboratory characteristics were observed between the two groups at baseline. Faster viral clearance occurred in the remdesivir/dexamethasone group compared to dexamethasone alone (median 6 vs 16 days; p<0.001). 30-days mortality in the remdesivir/dexamethasone group was 1.3%, while in dexamethasone alone was 16% (p<0.005). In the remdesivir/dexamethasone group compared to dexamethasone alone there was a reduction in hospitalization days (p<0.0001) and a faster improvement in both respiratory function and inflammatory markers.

Conclusions

Remdesivir/dexamethasone treatment is associated with significant reduction in mortality, length of hospitalization, and faster SARS-CoV-2 clearance, compared to dexamethasone alone

Non-invasive respiratory support in SARS-CoV-2 related acute respiratory distress syndrome: when is it most appropriate to start treatment?

BACKGROUND

Acute respiratory distress syndrome (ARDS) is one of the most severe complications of SARS-CoV-2 infection. Non-Invasive Respiratory Support (NRS) as Continuous Positive Airway Pressure (CPAP) and/or Non-Invasive Ventilation (NIV) has been proven as effective in the management of SARS-CoV-2-related ARDS. However, the most appropriate timing for start NRS is unknown.

METHODS

We conducted a prospective pilot study including all consecutive patients who developed moderate SARS-CoV-2-related ARDS during hospitalization. Patients were randomly divided into two intervention groups according to ARDS severity (assessed by PaO₂/FiO₂-P/F) at NRS beginning: group A started CPAP/NIV when P/F was ≤ 200 and group B started CPAP/NIV when P/F was ≤ 150. Eligible patients who did not give their consent to CPAP/NIV until the severe stage of ARDS and started non-invasive treatment when P/F ≤ 100 (group C) was added. The considered outcomes were in-hospital mortality, oro-tracheal intubation (OTI) and days of hospitalization.

RESULTS

Among 146 eligible patients, 29 underwent CPAP/NIV when P/F was ≤ 200 (Group A), 68 when P/F was ≤ 150 (Group B) and 31 patients agreed to non-invasive treatment only when P/F was ≤ 100 (Group C). Starting NRS at P/F level between 151 and 200 did not results in significant differences in the outcomes as compared to treatment starting with P/F ranging 101-150. Conversely, patients undergone CPAP/NIV in a moderate stage (P/F 101-200) had a significantly lower in-hospital mortality rate (13.4 vs. 29.0%, p = 0.044) and hospitalization length (14 vs. 15 days, p = 0.038) than those in the severe stage (P/F ≤ 100). Age and need for continuous ventilation were independent predictors of CPAP/NIV failure.

CONCLUSIONS

Starting CPAP/NIV in patients with SARS-CoV-2-related ARDS in moderate stage (100 > P/F ≤ 200) is associated to a reduction of both in-hospital mortality and hospitalization length compared to the severe stage (P/F ≤ 100). Starting CPAP/NIV with a P/F > 150 does not appear to be of clinical utility.

Clinical application of lung ultrasound score on COVID-19 setting: a regional experience in Southern Italy

OBJECTIVE

We aimed to assess the correlation between LUS Soldati proposed score and clinical presentation, course of disease and the possible need of ventilation support/intensive care.

PATIENTS AND METHODS

All consecutive patients with laboratory confirmed SARS-CoV-2 infection and hospitalized in two COVID Centers were enrolled. All patients performed blood gas analysis and lung ultrasound (LUS) at admission. The LUS acquisition was based on standard sequence of 14 peculiar anatomic landmarks with a score between 0-3 based on impairment of LUS picture. Total score was computed with their sum with a total score ranging 0 to 42, according to Soldati LUS score. We evaluated the course of hospitalization until either discharge or death, the ventilatory support and the transition in intensive care if needed.

RESULTS

One hundred and fifty-six patients were included in the final analysis. Most of patients presented moderate-to-severe respiratory failure (FiO2 <20%, PaO2 <60 mmHg) and consequent recommendation to invasive mechanic ventilation (CPAP/NIV/OTI). The median ultrasound thoracic score was 28 (IQR 18-36) and most of patients could be ascertained either in a score 2 (40%) or score 3 pictures (24.4%). The bivariate correlation analysis displayed statistically significant and high positive correlations between the LUS score and the following parameters: ventilation (rho=0.481, p<0.001), lactates (rho=0.464, p<0.001), dyspnea (rho=0.398, p=0.001) mortality (rho=0.410, p=0.001). Conversely, P/F (rho= -0.663, p<0.001), pH (rho = -0.363, p=0.003) and pO2 (rho = -0.400 p=0.001) displayed significant negative correlations.

CONCLUSIONS

LUS score improve the workflow and provide an optimal management both in early diagnosis and prognosis of COVID-19 related lung pathology.

Can Metformin Exert as an Active Drug on Endothelial Dysfunction in Diabetic Subjects?

Cardiovascular mortality is a major cause of death among in type 2 diabetes (T2DM). Endothelial dysfunction (ED) is a well-known important risk factor for the development of diabetes cardiovascular complications. Therefore, the prevention of diabetic macroangiopathies by preserving endothelial function represents a major therapeutic concern for all National Health Systems. Several complex mechanisms support ED in diabetic patients, frequently cross-talking each other: uncoupling of eNOS with impaired endothelium-dependent vascular response, increased ROS production, mitochondrial dysfunction, activation of polyol pathway, generation of advanced glycation end-products (AGEs), activation of protein kinase C (PKC), endothelial inflammation, endothelial apoptosis and senescence, and dysregulation of microRNAs (miRNAs). Metformin is a milestone in T2DM treatment. To date, according to most recent EASD/ADA guidelines, it still represents the first-choice drug in these patients. Intriguingly, several extraglycemic effects of metformin have been recently observed, among which large preclinical and clinical evidence support metformin’s efficacy against ED in T2DM. Metformin seems effective thanks to its favorable action on all the aforementioned pathophysiological ED mechanisms. AMPK pharmacological activation plays a key role, with metformin inhibiting inflammation and improving ED. Therefore, aim of this review is to assess metformin’s beneficial effects on endothelial dysfunction in T2DM, which could preempt development of atherosclerosis.

The relation between dietary habits and urinary levels of 3-phenoxybenzoic acid, a pyrethroid metabolite

Concerns about pesticide exposure through food consumption have increased during the past several years. Pyrethroids are applied as insecticides throughout the world. Human metabolism of pyrethroids results in urinary metabolites that are suitable for biological monitoring. The objective of our study was to investigate the relation between food consumption and urinary levels of 3-phenoxybenzoic acid (3-PBA), a general metabolite of pyrethroids, in a non-occupational exposed adult population from the IDI-IRCCS, Rome, Italy. Information on socio-demographic characteristics, smoking, diet and self-reported household pesticide exposure was collected. Urinary 3-PBA level of each subject was measured and adjusted by urinary creatinine. We found that people consuming both raw and cooked vegetables five times weekly or more had higher mean levels of 3-PBA in urine (1.03 μg/g creatinine versus 0.52 μg/g creatinine; p=0.009 and 0.99 μg/g creatinine versus 0.58 μg/g creatinine; p=0.01, respectively) than subjects consuming less than five times weekly. In a multivariate model, after adjusting for age, sex, BMI, smoking and household insecticide exposure, high intake of raw vegetables (OR: 5.31; 95%CI: 1.32-21.3) and high intake of cooked vegetables, in particular cruciferous (OR: 4.67; 95%CI: 1.07-20.5) and leafy vegetables (OR: 6.88; 95%CI: 1.50-31.7), were associated with high urine 3-PBA levels (≥0.70 μg/g creatinine). The results of this study suggest that part of the variation in pyrethrois intake is explained by vegetable intake.

Reference values of urinary trans,trans-muconic acid: Italian Multicentric Study

This article reports the results of a study, conducted in the framework of the scientific activities of the Italian Society for Reference Values, aimed at defining reference values of urinary trans,trans-muconic acid (t,t-MA) in the general population not occupationally exposed to benzene. t,t-MA concentrations detected in 376 subjects of the resident population in three areas of Italy, two in central (Florence and southern Tuscany) and one in northern Italy (Padua), by three laboratories, compared by repeated interlaboratory controls, showed an interval of 14.4-225.0 microg/L (5th-95th percentile) and a geometric mean of 52.5 microg/L. The concentrations measured were influenced by tobacco smoking in a statistically significant way: Geometric mean concentrations were 44.8 microg/L and 76.1 microg/Ll in nonsmokers (264 subjects) and smokers (112 subjects), respectively. In the nonsmoking population, a significant influence of gender was found when concentrations were corrected for urinary creatinine, geometric mean concentrations being 36.7 microg/g creatinine in males (128 subjects) and 44.7 microg/g creatinine in females (136 subjects). The place of residence of subjects did not seem to influence urinary excretion of the metabolite, although personal inhalation exposure to benzene over a 24-h period showed slightly higher concentrations in Padua and Florence (geometric means of 6.5 microg/m(3) and 6.6 microg/m(3), respectively) than in southern Tuscany (geometric mean of 3.9 microg/m(3)). Concentration of t,t-MA in urine samples collected at the end of personal air sampling showed little relationship to personal inhalation exposure to benzene, confirming the importance of other factors in determining excretion of t,t-MA when concentrations in personal air samples are very low.

Exposure to omethoate during stapling of ornamental plants in intensive cultivation tunnels: influence of environmental conditions on absorption of the pesticide

This report describes a study of exposure to omethoate during manual operations with ornamental plants in two intensive cultivation tunnels (tunnel 8 and tunnel 5). Airborne concentrations of omethoate were in the range 1.48-5.36 nmol/m(3). Total skin contamination in the range 329.94-12,934.46 nmol/day averaged 98.1 +/- 1.1% and 99.3 +/- 0.6% of the total potential dose in tunnel 8 and tunnel 5, respectively. Estimated absorbed doses during work in tunnel 5 were much higher than the acceptable daily intake of omethoate, which is 1.41 nmol/kg b.w. This finding shows that organization of the work or the protective clothing worn in tunnel 5 did not protect the workers from exposure. Urinary excretion of alkylphosphates was significantly higher than in the general population, increasing with exposure and usually showing a peak in the urine sample collected after the work shift. Urinary alkylphosphates showed a good correlation with estimated potential doses during work in tunnel 8 and are confirmed as sensitive biological indicators of exposure to phosphoric esters. The linear regression analysis between the urinary excretion of alkylphosphate, expressed as total nmol excreted in 24 h, and total cutaneous dose allows for estimating that the fraction of omethoate absorbed through the skin during work in tunnel 8 is about 16.5%.

Evaluation of skin and respiratory doses and urinary excretion of alkylphosphates in workers exposed to dimethoate during treatment of olive trees

This article describes a study of exposure to dimethoate during spraying of olive trees in Viterbo province in central Italy. Airborne concentrations of dimethoate were in the range 1.5 to 56.7 nmol/m(3). Total skin contamination was in the range 228.4 to 3200.7 nmol/d and averaged 96.0% +/- 3.6% of the total potential dose. Cotton garments afforded less skin protection than waterproof ones, which were in turn associated with higher skin contamination than disposable Tyvek overalls. Total potential doses and estimated absorbed doses, including their maxima, were below the acceptable daily intake of dimethoate, which is 43.6 nmol/kg body weight (b.w.). Urinary excretion of alkylphosphates was significantly higher than in the general population, increasing with exposure and usually showing a peak in the urine sample collected after treatment. Metabolite concentrations were influenced by the type of individual protection used: minimum levels were associated with the closed cabin and maximum levels with absence of any respiratory or hand protection. Urinary alkylphosphates showed a good correlation with estimated absorbed doses and are confirmed as sensitive biologic indicators of exposure to phosphoric esters.

Biological monitoring of exposure to chlorpyrifos-methyl by assay of urinary alkylphosphates and 3,5,6-trichloro-2-pyridinol

The results of biological monitoring by assay of urinary 3,5,6-trichloro-2-pyridinol and alkylphosphates (DMP, DMTP) in groups of 9 and 2 workers exposed to chlorpyrifos-methyl during vine spraying and manual leaf thinning 5-11 d after spraying, respectively, are reported. The results are compared with those of a control group of 46 subjects not occupationally exposed to organophosphate insecticides. Significantly higher urinary excretion of metabolites (Mann-Whitney U-test) was found in both groups than in controls. Levels of 3,5,6-trichloro-2-pyridinol (mean +/- SD) were 15.9 + 10.6 nmol/g creatinine (n = 33) for controls, 92.4 + 162.5 nmol/g creatinine (n = 20) for manual workers, and 675.5 + 1110.8 nmol/g creatinine (n = 48) for workers spraying and mixing the insecticide. Levels of DMP (mean +/- SD) were 63.8 + 100.1 nmol/g creatinine (n = 42), 123.0 + 79.0 nmol/g creatinine (n = 20), and 577.2 + 1003.2 nmol/g creatinine (n = 61), respectively, for the same 3 groups. Levels of DMTP (mean +/- SD) were 153.4 + 164.4 nmol/g creatinine (n = 43), 489.3 + 288.3 nmol/g creatinine (n = 20), and 297.6 + 215.4 nmol/g creatinine (n = 61), respectively, for the same 3 groups. Good correlations were found between urinary excretion of 3,5,6-trichloro-2-pyridinol and DMP (r = .776 for manual workers; r = .775 for workers mixing and spraying the insecticide) or DMTP (r = .558 and r = .746, respectively for the same 2 groups). The peak of excretion of the three metabolites was found in urine samples collected the night after the spraying or leaf thinning operations.

[Environmental and biological reference values of plant pesticides]

A wide range of studies concerned with the definition of environmental and biological reference values for plant pesticides is reviewed. All phases of data production are critically assessed, including sampling, sample preparation and analysis, choice of population, statistical analysis and expression of results. The importance of the studies for the definition of reference values useful in the sectors of environmental hygiene and occupational toxicology is also examined. Most of the studies were based on American populations, though work on reference values has also recently been done by Italian authors, particularly the SIVR, which has published data on 3,5,6-trichloro-2-pyridinol and ethylenethiourea in urine. Because the number of the studies is small and more detail about variables is needed, the lists of reference values, given separately for American and Italian populations, also include proposals and attempts at definition of reference values. When available, biological reference values (BRV) are given separately for adults and children, emphasising the greater intake of the infant population due to higher food intake per unit body weight and greater exposure to contaminants present in the domestic environment. BRVs for plant pesticides generally depend on factors such as smoking, wine consumption and diet, major sources of residue intake for the human population.

[Reference values of urinary mercury in the Italian population]

This paper shows the results of a polycentric study performed to assess the reference values of urinary mercury (U-Hg) in Italian population. 374 subjects from four Italian cities (Bari, Brescia, Genova e Siena) have been examined. A questionnaire on life style, dietary habits, occupational or environmental exposure to Hg and clinical history has been administered to every participant and number and surface of dental amalgams have been verified for all subjects. The determination of U-Hg has been performed on urinary extemporary samples by hydride generation atomic absorption method (HG-AAS); urinary creatinine has been determinated to reduce the intraindividual variability. U-Hg reference values were: 0.21-3.20 micrograms/g creat (5 degrees and 95 degrees percentile) and 0.12-6.04 micrograms/g creat (range). Moreover study results have shown that number and surface of dental amalgams, dietary fish intake and body mass index (BMI) influenced significatively U-Hg excretion. U-Hg reference values from this polycentric study resulted comparable to those assessed in other European countries, whereas the mean U-Hg observed in the referent Italian population was lower.

[Biologic monitoring of occupational and non-occupational exposure to pesticides]

Occupationally or otherwise, much of the population is exposed to pesticides. To obtain information on exposure levels, biological monitoring is often the best choice because it provides data that reflects total exposure by all routes. Biological monitoring has been used to evaluate exposure in agricultural and industrial environments, in subjects poisoned by accidental or voluntary contact, in volunteers for pharmacokinetic studies and in the general population. This paper is based on 100 studies published on this topic and reviews exposure indices for the main classes of pesticides. Methods of sampling and conservation of samples are outlined, together with the analytical procedures used. For compounds such as organophosphate and pyrethroid insecticides, ethylenebisdithiocarbamate fungicides, and phenoxyacetic herbicides, the results of studies on the general population and groups of occupationally exposed workers are reported.

Assessment of reference values for mercury in urine: the results of an Italian polycentric study

The results of a polycentric study to assess the reference values of urinary mercury (U-Hg) in four Italian cities are presented. A total of 383 subjects were selected on the basis of standardised criteria by a questionnaire on personal habits, lifestyle, occupational or non-occupational exposure to Hg, medical history, number and area of dental amalgams. U-Hg was determined by hydride generation atomic absorption method (HG-AAS), with a detection limit of 0.5 microg/l and by flow injection (FI) inductively coupled plasma mass spectrometry (ICP-MS), with a detection limit of 0.03 microg/l. The median value of U-Hg, determined by HG-AAS, was 0.78 microg/g creatinine (0.75 for males and 0.83 for females), with 5 degrees and 95 degrees percentiles, respectively, of 0.17 and 3.66 microg/g creatinine. When determined by FI ICP-MS, the median value was 0.79 microg/g creatinine (0.77 for males and 0.79 for females) with 5 degrees and 95 degrees percentiles of, respectively, 0.12 and 5.02 microg/g creatinine. Among the independent variables, city of origin, area of dental amalgams, fish intake and tobacco smoking significantly influenced the U-Hg levels. The U-Hg reference values from this survey are lower than those from other recent investigations, probably due to characteristics and selection of the examined individuals and to the strict control of pre-analytical and analytical factors of variability.

Evaluation of respiratory and cutaneous doses and urinary excretion of alkylphosphates by workers in greenhouses treated with omethoate, fenitrothion, and tolclofos-methyl

This research evaluated exposure pathways across work tasks for three organophosphate pesticides in a group of greenhouse workers. During reentry in ornamental plant greenhouses, five male workers were monitored for five consecutive days. Skin contamination (excluding hands) was evaluated with nine pads of filter paper placed on the skin. Hand contamination was assessed by washing with 95% ethanol. Respiratory exposure was evaluated by personal air sampling. The respiratory dose was based on a lung ventilation of 20 L/min. The doses absorbed were estimated assuming 10% skin penetration and 100% lung retention. Urinary alkylphosphates were assayed in the 24-hour urine samples of the days on which exposure was evaluated. Respiratory exposure was usually less than skin contamination, being 4.5 +/- 8.4%, 9.9 +/- 10.0%, and 49.5 +/- 26.6% (mean +/- standard deviation) of total exposure for omethoate, tolclofos-methyl, and fenitrothion, respectively. Multiple regression analysis showed that urinary alkylphosphate (nmol/24 hours) (y) was significantly correlated (r = 0.716, p < 0.001) with the respiratory doses of the three active ingredients absorbed the same day (x1) and with the cutaneous dose absorbed the previous day (x2). The relationship was expressed by the equation y = 0.592x2 + 0.117x, + 156.364. The doses of omethoate absorbed by one worker were more than 45 times the acceptable daily intake (ADI) of 1.41 nmol/kg body weight (b.w.) The ADI for fenitrothion and tolclofos-methyl (10.8 and 212.6 nmol/kg body weight, respectively) were never exceeded. High absorption by one worker underlines the importance of correct use of protective clothing. In this study the hands were always a source of contact with the pesticides. Greater precautions should be taken to reduce contamination (clean gloves, constant use of gloves).

Biologic monitoring of exposure to organophosphorus pesticides in 195 Italian children

One hundred ninety-five 6- to 7-year-old children who lived in the municipality of Siena (Tuscany, Italy), underwent biologic monitoring to evaluate urinary excretion of several alkylphosphates that are metabolites of organophosphorus pesticides. We evaluated dimethylphosphate (DMP), dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), diethylphosphate (DEP), diethylthiophosphate (DETP), and diethyldithiophosphate (DEDTP). We obtained urine samples taken in the children's schools, and each sample was accompanied by a questionnaire about lifestyle and dietary habits. We found DMP and DMTP in detectable concentrations in the greatest number of samples (96 and 94%, respectively). The DMP values were geometric mean (GM) 116.7, [geometric standard deviation (GSD) 2.5], and a range of 7.4-1,471.5 nmol/g creatinine. The corresponding DMTP values were GM 104.3 (GSD 2.8) and a range of 4.0-1,526.0 nmol/g creatinine. DMDTP, DEP, DETP, and DEDTP concentrations were GM 14.1, (GSD 3.0), and a range of 3.3-754.6 nmol/g creatinine in 34% of the children; GM 33.2, (GSD 2.4), and a range of 5.1-360.1 nmol/g creatinine in 75% of the children; GM 16.0, (GSD 2.9), and a range of 3.1-284.7 in 48% of the children; and GM 7.7, (GSD 2.1), and a range of 2.3-140.1 in 12% of the children, respectively. The significant variable for urinary excretion of these metabolites in children was pest control operations performed inside or outside the house in the preceding month; however, the presence of a vegetable garden near the house rarely emerged. The urinary excretion of alkylphosphates in children was significantly higher than in a group of the adult population resident in the same province.

Biologic monitoring of exposure to organophosphorus pesticides in 195 Italian children

One hundred ninety-five 6- to 7-year-old children who lived in the municipality of Siena (Tuscany, Italy), underwent biologic monitoring to evaluate urinary excretion of several alkylphosphates that are metabolites of organophosphorus pesticides. We evaluated dimethylphosphate (DMP), dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), diethylphosphate (DEP), diethylthiophosphate (DETP), and diethyldithiophosphate (DEDTP). We obtained urine samples taken in the children's schools, and each sample was accompanied by a questionnaire about lifestyle and dietary habits. We found DMP and DMTP in detectable concentrations in the greatest number of samples (96 and 94%, respectively). The DMP values were geometric mean (GM) 116.7, [geometric standard deviation (GSD) 2.5], and a range of 7.4-1,471.5 nmol/g creatinine. The corresponding DMTP values were GM 104.3 (GSD 2.8) and a range of 4.0-1,526.0 nmol/g creatinine. DMDTP, DEP, DETP, and DEDTP concentrations were GM 14.1, (GSD 3.0), and a range of 3.3-754.6 nmol/g creatinine in 34% of the children; GM 33.2, (GSD 2.4), and a range of 5.1-360.1 nmol/g creatinine in 75% of the children; GM 16.0, (GSD 2.9), and a range of 3.1-284.7 in 48% of the children; and GM 7.7, (GSD 2.1), and a range of 2.3-140.1 in 12% of the children, respectively. The significant variable for urinary excretion of these metabolites in children was pest control operations performed inside or outside the house in the preceding month; however, the presence of a vegetable garden near the house rarely emerged. The urinary excretion of alkylphosphates in children was significantly higher than in a group of the adult population resident in the same province.

Multiroute exposure assessment and excretion of urinary metabolites of fenitrothion during manual operations on treated ornamental plants in greenhouses

The results of environmental and biological (five subjects) monitoring of exposure to fenitrothion during manual operations on treated ornamental plants in greenhouses are reported. Urinary excretion [GM (GSD)] of alkylphosphates [dimethylphosphate (DMP) + dimethylthiophosphate (DMTP)] (nmol/g creat) was 244.8 (1.8), 174.0 (2.0), and 354.4 (1.6) respectively, on the first (Monday), third (Wednesday), and fifth (Friday) days of work. These levels were not significantly higher than those recorded in a control group (21 subjects) in which urinary excretion [GM (GSD)] of DMP + DMTP was 102.8 (4.2) nmol/g creat. Air concentrations of fenitrothion (nmol/m3) ranged from 45.5 to 81.2 on Monday, 17.3 to 27.1 on Wednesday, and 9.7 to 19.1 on Friday. Dose estimates showed that the respiratory-absorbed doses of fenitrothion accounted, on the average (GM), for 94.7%, 93.1%, and 91.5% of the total absorbed dose on Monday, Wednesday, and Friday, respectively. Multiple regression analysis showed a significant correlation (r2 = 0.595) between urinary excretion of DMP + DMTP, respiratory-absorbed dose, and skin-absorbed dose, estimated on Monday and Wednesday. Total estimated absorbed doses did not exceed the acceptable daily intake for fenitrothion. Serum and erythrocyte cholinesterase activities were not significantly different before and after exposure.

Reference values of urinary 3,5,6-trichloro-2-pyridinol in the Italian population--validation of analytical method and preliminary results (multicentric study)

The interlaboratory validation of analytical procedures for the assay of urinary 3,5,6-trichloro-2-pyridinol (TCP) in the general Italian population is reported. The determinations were performed by high-resolution gas chromatography (HRGS) with electron capture detection and HRGS with mass spectrometry (MS) in 2 laboratories. The urine samples were from 42 participants from 3 regions of Italy. The results were evaluated by interlaboratory quality control. Urinary TCP concentrations were above the detection limit (1.2 micrograms/L) in 88% of the population, with a mean detectable concentration [GM (GSD)] of 2.8 (1.9) micrograms/g creatinine (creat). (GM, geometric mean; GSD, geometric standard deviation.) The Mann-Whitney U test showed that wine consumption was a statistically significant variable (p < 0.05) for urinary concentrations of TCP. Analysis of variance of the logarithm of urinary TCP versus wine consumption and diet showed a statistically significant fit. The model used explained 30% of the total variance: wine consumption and diet accounted for 37 and 17% respectively of the explained variance.

[The risk of lead and health conditions of exposed workers in the Siena region]

A number of studies on the health of occupational exposure to lead of workers from various industrial sectors are summarized. These studies document the disappearance of severe cases of saturnism, as seen in the past, and the occurrence nowadays, mainly of sub-clinical manifestations, such as alterations of blood levels of lead and protoporphyrin IX, in the large majority of cases. For the period 1984-95, a statistical analysis of the results obtained for these parameters is reported, together with other clinical data, for seven industrial sectors: crystal, ceramics, chemistry, metallurgy and mechanics, iron and steel, printing and painting. These results show a drop of the mean concentrations of blood lead levels in all sectors but the ceramic industry, especially since 1991, when the law, Decreto Legislativo 277/91--in accomplishment of European directives on protection of workers, including the directive 82/605/EEC--has been put into force.

Prediction of percutaneous absorption from physicochemical data: a model based on data of in vitro experiments

Correlations between in vitro percutaneous absorption data and physicochemical properties of industrial chemicals are evaluated in order to develop predictive mathematical models based on said properties. Percutaneous diffusion of 16 pounds of occupational interest, eight of which were polycyclic aromatic hydrocarbons (acenaphthene, anthracene, benzo(a)anthracene, chrysene, phenanthrene, fluorene, naphthalene, pyrene), six organophosphorus insecticides (acephate, chlorpyrifos, dimethoate, fenitrothion, methamidophos, omethoate) and two phenoxycarboxylic herbicides (2,4-D, MCPA), were tested in vitro using monkey (Cercopithecus aetiops) skin. The test apparatus consisted of nine static diffusion cells with normal saline, gentamycin sulphate and 4% bovine serum albumin as receiving solution. Test compounds were applied at various concentrations in 30 microliters of acetone solution and determined, in the receiving phase, by chemical analysis. Values for ln Kow (octanol/water partition coefficient) were correlated with experimentally determined values of the permeability constant Kp (r = 0.90, P < 0.001) and lag time (r = 0.81, P < 0.01). Analysis of variance in a model of multiple linear regression between Kp, ln Kow and water solubility [water] of the compounds, showed that the data had a highly significant fit (P < 0.0001). A more general model which also included molecular weight (MW) and vapour pressure was evaluated as well, but the two variables made no substantial difference. Multiple regression analysis between lag time, ln Kow and [water] was significant (P < 0.0001), whereas introduction of vapour pressure and MW as independent variables did not significantly improve the predictive effect on lag time. Our experimental system, therefore, enables the values of Kp and lag time to be predicted with reasonable precision on the basis of ln Kow and [water] values, using the algorithm derived from the multiple linear regression equation.

Environmental and biological monitoring of exposure to mancozeb, ethylenethiourea, and dimethoate during industrial formulation

The results of environmental (11 subjects) and biological (57 subjects) monitoring of exposure to mancozeb, ethylenethiourea (ETU), and dimethoate are reported for employees of a firm producing commercial formulations containing these active ingredients. Urinary excretion [GM(GSD)] of ETU (microg/g creatinine) and alkylphosphates [dimethylphosphate (DMP) + dimethylthiophosphate (DMTP) + dimethyldithiophosphate (DMDTP)] (nmol/g creatinine) was 65.3(4.8) and 419.2(2.1), respectively, for employees engaged in the formulation of a product containing 80% mancozeb (n = 9), 36.6(1.9) and 296.4(2.4) for those formulating a product containing 35% mancozeb (n = 9), 9.5(6.1) and 1022.4(3.0) for those engaged in plant maintenance and internal transport of materials (n = 6), 10.3(4.2) and 322.8(3.3) for those engaged in packaging the mancozeb formulations (n = 16), 4.4(3.3) and 2545.4(3.9) for those formulating a product containing 40% dimethoate (n = 11), and 3.0(2.7) and 871.7(3.3) for those bottling the same dimethoate formulation (n = 10). Air concentrations (microg/m3) ranged from 25.3 to 194.4 for dimethoate, from 0.2 to 1.3 for ETU, and from 139.9 to 949.0 for mancozeb. Urinary excretion of ETU and alkylphosphates showed a significant correlation with mancozeb (r2 = .971), and ETU (r2 = .858), and dimethoate (r2 = .955) contamination of the hands. Potential dose estimates showed that the potential respiratory doses of mancozeb and dimethoate accounted, on the average, for 38% of the total potential dose. The potential respiratory dose of ETU was 7% of the total potential dose. Total estimated absorption did not exceed the accepted daily dose (ADI) for ETU and mancozeb, but the ADI for dimethoate was exceeded. Serum and erythrocyte cholinesterase activities in workers formulating dimethoate products were not significantly different before and after exposure.

Urinary excretion of ethylenethiourea in five volunteers on a controlled diet (multicentric study)

Urinary excretion of ethylenethiourea (ETU) was monitored for 8 days in a group of five male non-smoker volunteers on a diet, the items of which were assayed for ETU and carbon sulphide. Urinary excretion of ETU reflected the consumption of wine, fruit and vegetables. Urinary ETU concentrations ranged from 0.6 to 6.7 micrograms/g creatinine. ETU concentrations in the food eaten by the volunteers were generally below the detection limit whereas in wine 8.8 micrograms/l ETU was detected. Evolution of carbon sulphide by food samples ranged from 0.03 to 0.17 mg/kg. Mean (+/- S.D.) daily intake of ETU in wine was 3.5 +/- 0.2% of the acceptable daily intake (ADI): 0.070 +/- 0.004 micrograms/kg body wt. During the 8 days of the study, an average of 48.3% of the ETU ingested in wine was excreted unmodified by the kidneys. Twenty-four hour urinary excretion of ETU was significantly correlated with daily intake of ETU (r = 0.768) and CS2 evolved by the daily food items (r = 0.414).

Analytical method for the determination of urinary 3-phenoxybenzoic acid in subjects occupationally exposed to pyrethroid insecticides

The determination of urinary 3-phenoxybenzoic acid enables exposure to pyrethroid insecticides to be evaluated. A method for the quantitative determination of this metabolite in urine is described. The compound and the internal standard (2-phenoxybenzoic acid) are derivatized with pentafluorobenzylbromide and transformed into pentafluorobenzyl esters, which are determined by gas chromatography with an intermediate polarity capillary column and an electron-capture detector. Before GC analysis, the urinary extracts are purified on LC-Si SPE columns. The proposed method has a detection limit of 0.5 microg/l and a mean recovery of 91.3%. The coefficient of variation of the analytical procedure, evaluated at a concentration of 24.96 microg/l, was 9.58%. Storage of the urine samples for 3 months at -18 degrees C did not lead to significant changes in the concentration of analyte. The method was tested analysing the urine of a farm worker with symptoms of pyrethroid poisoning, occupationally exposed to esfenvalerate.

In vitro percutaneous penetration of methyl-parathion from a commercial formulation through the human skin

OBJECTIVE

To compare in vitro percutaneous absorption of methyl-parathion dissolved in an acetone vehicle and in the form of a commercial formulation.

METHODS

Penetration through the human skin was measured in Franz diffusion cells with full thickness skin from a human cadaver as the membrane. The two tailed non-parametric Mann-Whitney U test was used to compare the cumulative diffusion of methyl-parathion in the receptor fluid of the cells at various time intervals.

RESULTS

In vitro skin penetration of methyl-parathion was significantly higher with the commercial formulation. The percentage of the applied dose absorbed after 24 hours was 5.20% v 1.35%. The mean lag time was < 8 hours.

CONCLUSION

Assessments of uptake and internal dose after exposure to pesticides should be based on the commercial products rather than active ingredients, because of the crucial role of the vehicle, as shown in this study.

Analytical methods for the determination of urinary 2,4-dichlorophenoxyacetic acid and 2-methyl-4-chlorophenoxyacetic acid in occupationally exposed subjects and in the general population

Two methods for the quantitative analysis of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) in urine were compared. The first was an high-performance liquid chromatography method using a C8 column with ion suppression and diode array detection. The urine extracts were first purified by solid-phase extraction (SPE) on silica capillary columns. The detection limit of the method was 15 micrograms/L for both compounds. The percentage coefficient of variation of the whole analysis evaluated at a concentration of 125.0 micrograms/L was 6.2% for 2,4-D and 6.8% for MCPA. The mean recovery of analysis was 81% for 2,4-D and 85% for MCPA. The second was a gas chromatographic (GC) method in which the compounds were first derivatized with pentafluorobenzylbromide to pentafluorobenzyl esters, which were determined with a slightly polar capillary column and electron capture detection. Before GC analysis, the urine extracts were purified by SPE on silica capillary columns. This method had a detection limit of 1 microgram/L for both compounds and a percentage coefficient of variation of the whole analysis, evaluated at a concentration of 30.0 micrograms/L, of 8% for 2,4-D, and of 5.5% for MCPA. the mean recovery was 87% for 2,4-D and 94% for MCPA. The low detection limit made the second method suitable for assaying the two herbicides in the general population. Duplicate analysis of ten urine samples from occupationally exposed subjects by the two methods gave identical results for a wide range of concentrations.

Solubilization of lead from crystal dust in protein solution (pseudointerstitial fluid) and gastric juice

Since several workers engaged in polishing and engraving crystal articles were found to have higher than average blood levels of lead (560 micrograms/liter, range 80-560 micrograms/liter), we investigated the hypothesis that crystal dust releases lead in the human body. To test the hypothesis, two types of crystal polishing dusts, having different lead contents, were mixed with human serum diluted 1:3 (pseudointerstitial fluid), gastric juice, and phosphate buffer at pH 9. After 14 days of contact, the diluted serum had extracted 0.620% of the lead in the crystal dust (particle size < 20 microns) containing 25.2% lead and 0.425% of that containing 19.9% lead. After 48 hr in gastric juice, 0.235 and 0.556% of the lead was extracted from crystal dusts (unsieved crystal dusts) containing 25.2 and 19.9% lead, respectively. After 28 days in alkaline solution, 0.358 and 0.304% of the lead was extracted respectively from the same two crystal dusts (unsieved crystal dusts).

Environmental and urinary reference values as markers of exposure to hydrocarbons in urban areas

A study using individual dosimetry to evaluate the daily inhaled dose of sixteen aromatic and aliphatic hydrocarbons in three groups of primary school children, living in three Italian towns with 50,000 inhabitants or less, (Treviglio-Lombardy; Poggibonsi-Tuscany; Valenza-Piedmont) is presented. The simultaneous use of two passive samplers (radial diffusion) for each child, for a 24 h period, determined both the indoor and indoor + outdoor environmental reference concentrations. We measured the urinary levels of benzene, toluene, ethylbenzene and xylenes for each child and hence determined the urinary reference values for BTEX. We also considered the possibility of using benzene in urine as a biomarker of environmental exposure of the general population to this xenobiotic. We evaluated how both the environmental and biological measures were influenced by the presence of smokers in the surveyed children's houses. For the group of children living in Poggibonsi, we considered the influence of the living area and the traffic density on environmental concentrations of benzene (indoor and indoor + outdoor).

Reference values of urinary ethylenethiourea in four regions of Italy (multicentric study)

The results of a study in which urinary ethylenethiourea (ETU) was assayed in the general population (167 subjects) of four Regions of Italy (Veneto, Lombardy, Piedmont and Trentino Alto Adige) are reported. The results are compared with those in a population of 97 subjects from Rovescala, a hillside wine-producing town a few kilometers from Pavia, where ethylenebisdithiocarbamates are sprayed by helicopter. It was found that an average of 24% of the populations of the four regions, taken together, had urinary ETU levels above detection limits (1.0 microgram 1(-1)) as compared to 37% of the population of Rovescala. The ranges of concentration were 0.8-8.3 micrograms 1(-1) for the four regions and 0.9-61.4 micrograms 1(-1) for Rovescala. Statistically significant variables for urinary ETU levels were smoking and wine drinking.

Analytical method for the determination of urinary alkylphosphates in subjects occupationally exposed to organophosphorus pesticides and in the general population

The determination of urinary alkylphosphates monitors occupational exposure to organophosphorus pesticides and insecticides. This paper describes a method for the quantitative determination of the following metabolites: O,O-dimethylphosphate (DMP), O,O-diethylphosphate (DEP), O,O-diethyldithiophosphate (DETP), O,O-dimethyldithiophosphate (DMDTP), O,O-diethyldithiophosphate (DEDTP), and O,O-dimethylthiophosphate (DMTP). The compounds are derivatized with pentafluorobenzylbromide into pentafluorobenzyl esters which are determined by gas chromatography with a capillary column of intermediate polarity and a flame photometric detector specific for phosphorus. Before the analytical gas chromatographic stage, the urinary extracts are purified on isolute SPE CN columns. The proposed method has a limit of detection of 2-3 micrograms/L at 62.5 micrograms/L and a mean recovery of the purification stage of 85.8-101.0% for all six compounds. The coefficient of variation of the analytical procedure was 7.9-11.9% for the six compounds. The low detection limits make this method suitable also for determining the six metabolites in the general population.

Urinary excretion of alkylphosphates in the general population (Italy)

Xenobiotic residues and their metabolites in biological fluids of the general population are an important indicator of exposure to toxic substances dispersed in the environment. Urine samples collected from 124 subjects living in SW Tuscany, Italy were analyzed for alkylphosphates (dimethylphosphate, dimethylthiophosphate, dimethyldithiophosphate, diethylphosphate, diethylthiophosphate, diethyldithiophosphate), aspecific metabolites of organophosphorus insecticides. The compound most frequently found was dimethylthiophosphate which was detectable in 99% of the subjects analyzed, with a geometric mean of 70.7 nmol/g creatinine. The other substances were found in the following percentages of our population, at the following mean concentrations: dimethylphosphate, 87%, 62.8 nmol/g creat.; dimethyldithiophosphate, 48%, 21.1 nmol/g creat.; diethylphosphate, 81%, 27.4 nmol/g creat.; diethylthiophosphate, 73%, 22.8 nmol/g creat.; diethyldithiophosphate, 7%, 13.7 nmol/g creatinine. Subjects eating food (fruit, meat, vegetables) that was not their own produce showed higher urinary concentrations of nearly all the compounds. The other variables considered (sex, age, residence, alcohol, smoking, sampling period) seem to affect the percentages of positive values of the various substances but to different degrees. Age and source of foods were the most important variables for dimethylthiophosphate excretion when mean values were analyzed by Student's t-test and analysis of variance (ANOVA).

Serum erythropoietin and blood lead concentrations

The aim of the study was to test the hypothesis that high blood lead levels are associated with depressed serum erythropoietin concentrations in workers occupationally exposed to lead. The results in exposed workers and in a control group of unexposed subjects were compared. Blood lead values were < or = 20 micrograms/dl in unexposed subjects and > or = 30 micrograms/dl in exposed subjects. The two groups of exposed workers and the control population were matched for sex and age. Hemoglobin levels were not affected by blood lead values and did not differ significantly between the three groups. The two-tailed, nonparametric Mann-Whitney U-test was used to compare unpaired groups. The Spearman rank correlation test was used to evaluate the dose-effect relationship between Pb and EPO. The analysis of the data indicate that erythropoietin values are significantly lower in exposed subjects than a controls. However no correlation was demonstrated between blood lead concentrations and erythropoietin in any group.

[Percutaneous absorption of phenanthrene: an in vitro study of the monkey skin]

It is well known that polycyclic aromatic hydrocarbons (PAHs) are absorbed through the skin of experimental animals and humans. However dermal uptake of PAHs is difficult to assess due to the lack of specific studies. The aim of this study was to obtain in vitro percutaneous absorption data for phenanthrene. In vitro penetration was measured with excised monkey (Cercopithecus Aethiops) skin in Franz diffusion cells, using a saline solution with 4% bovine serum albumin and gentamicin sulfate as receptor fluid. In two different groups of 7 and 2 cells, 38.1 and 95.3 nmol/cm2 respectively of phenanthrene were applied in an acetone vehicle. The absorption rate in the first group of 7 cells was 0.025 nmol/cm2/h (S.D. = 0.012), the lag time 11.7 (S.D. = 7.0) h and the breakthrough time 70 m (S.D. = 55 m). In the second group of 2 cells, the average absorption rate was 0.066 nmol/cm2/h and the average lag time 11.8 h. The percutaneous absorption at 24, 48 and 72 hours in the 7 cell group was 0.72% (S.D. = 0.52), 2.51% (S.D. = 1.76) and 3.9% (S.D. = 2.0) of the applied dose respectively. In the 2-cell group 1.1%, 2.78% and 4.5% of the applied dose was absorbed at 24, 48 and 72 hours. The results of the present study confirm the extent of percutaneous absorption of phenanthrene. The data can be compared with dermal absorption values of other PAHs obtained under the same experimental conditions.

Biological monitoring of exposure to organophosphorus insecticides by assay of urinary alkylphosphates: influence of protective measures during manual operations with treated plants

Biological monitoring was carried out by assaying urinary dimethylated alkylphosphates [dimethyldithiophosphate (DMDTP), dimethylthio-phosphate (DMTP), and dimethylphosphate (DMP)] in 11 workers exposed to chlorpyrifos-methyl and azinphosmethyl during operations in a previously sprayed peach orchard. The subjects were divided into groups on the basis of the protective clothing worn. The results were compared with those of a reference group of 99 subjects not occupationally exposed to organophosphorus insecticides. The hand-wash liquid of the workers was also analyzed to evaluate skin contamination. Significantly higher levels of urinary excretion of alkylphosphates were found in all groups than in unexposed controls (Student's t test). A good correlation was found between quantities of the active ingredients on the hands and urinary excretion of total dimethylated alkylphosphates (r = 0.788) and of DMTP (r = 0.749) and DMP (r = 0.790) alone. The correlation between azinphos-methyl on the hands and urinary excretion of DMDTP was poor (r = 0.069). Under the working conditions investigated, the main route of absorption seems to be via the skin. Respiratory absorption, however, also appears significant in view of the difference in urinary excretion of dimethylated alkylphosphates found between subjects with and without face masks.

[Evaluation of omethoate and fenitrothion absorption in greenhouse workers using protective equipment in confined areas]

Sprayers and workers engaged in manual operations in a greenhouse were monitored for exposure to omethoate and fenitrothion. Urinary dialkyl phosphates (dimethyl thiophosphate and dimethyl phosphate) were used as biological index of exposure to the two chemicals. Residues of fenitrothion on foliage were measured as well as levels of fenitrothion and omethoate in air samples collected in the breathing zone (personal sampling) and in the work-place near the entrance and the end of the greenhouse (static sampling). Skin exposure was estimated from pads placed on the thorax under overalls and from hand washing liquid at the end of the workshift. Sprayers wore respiratory and skin protection during the workshift. Workers engaged in manual operations did not wear respiratory protection. Re-entry to the greenhouse was permitted 48 h after spraying. Levels of omethoate and fenitrothion in air samples, on pads and on the hands, during manual operations on ornamental plants, were very low. Urine analysis shoved no significant difference between the pre- and post-exposure samples. No significant difference was found between levels of urinary dialkyl phosphates in the control group and exposed workers. Cholinesterase activity (acetyl and butyryl) showed no significant reduction at the end of the workshift compared with baseline values.

[Evaluation of urinary excretion of ethylenethiourea in subjects occupationally and non-occupationally exposed to ethylenebis(dithiocarbamates)]

Ethylenebisdithiorcabamate (EBDC) fungicides are broken down metabolically and in the environment to ethylenethiourea (ETU), a suspected carcinogen. Urinary ETU was assayed in control groups and subjects occupationaly exposed to EBDC and was found to be an excellent indicator of exposure both to ETU and EBDC. Correct use of protective clothing greatly reduced exposure and urinary excretion of ETU. ETU was excreted, albeit in low concentrations, in a high percentage (91% and 30%) of subjects in both control groups, demonstrating its utility as an indicator of widespread EBDC contamination.

Comparison of HPTLC and HPLC procedures for the determination of certain xenobiotic residues in apples and pears

HPTLC was used to check for residues of benomyl, carbendazim, ethoxyquin and thiabendazole in apples and pears. The method used showed good precision with a percentage coefficient of variation of less than 5%; recoveries were always greater than 90%. The limits of determination using HPTLC were always at least four times lower than Italian statutory limits. Selectivity with respect to other matrix components was excellent for all fruit varieties tested. Comparison with HPLC confirmed the validity of the results.

Comparison of an HPTLC and an HPLC procedure for the determination of chlorpropham, propham and thiabendazole residues in potatoes

HPTLC was used to check for residues of chlorpropham, propham (sprout inhibitors) and thiabendazole (fungicide) applied to potatoes. The method used gave good precision and analytical sensitivity. The sample preparation method developed by the authors was simple and gave good recovery and selectivity as far as other components of the matrix were concerned. Comparison with liquid chromatography confirmed the validity of the results.