Gianfranco Sciarra

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 Students t-test and analysis of variance (ANOVA).

Urinary 1-hydroxypyrene as a marker of exposure to pyrene: an epidemiological survey on a general population group.

Urinary levels of 1-hydroxypyrene in a general adult population group are studied. Experimental data are not normally distributed; statistical analysis required a base 10 logarithmic transformation of data. The concentrations of urinary 1-hydroxypyrene measured were expressed as microgram g-1 urinary creatinine and are comparable with those reported by other authors, both for smoker and non-smoker subgroups. Multiple regression analysis shows that, for smokers, the number of cigarettes smoked per day and the body mass index (BMI) significantly influence the levels of urinary 1-hydroxypyrene expressed as microgram g-1 urinary creatinine, whereas no personal or behavioural variable (age, sex, alcohol consumption, dietary intake of pyrene, BMI) modified the 1-hydroxypyrene levels for non-smokers.

Biological monitoring of exposure to organophosphorus insecticides by assay of urinary alkyl phosphates: 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 (Students 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.

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.

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.

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).

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.

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).

Evaluation of respiratory and cutaneous doses of chlorothalonil during re-entry in greenhouses.

Five female workers were monitored for 5 consecutive days during re-entry into a greenhouse containing ornamental plants. 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 15 l/min. The doses absorbed were estimated assuming 10% skin absorption and 100% lung retention. Dislodgeable foliar residue was determined on days of re-entry to evaluate the decay of chlorothalonil. Chlorothalonil was analysed in the different matrices by GC-MS. Respiratory exposure was less than skin contamination, being 11.4+/-5.1% (mean+/-SD) of total exposure. The estimated total absorbed dose did not exceed the acceptable daily intake of 0.03 mg/kg body mass. The hands and unexposed skin of all workers were always found to be contaminated. Greater precautions are therefore needed to reduce skin exposure (clean gloves and suitable clean clothing every day).

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

Abstract. 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.