Zlatko Fröbe

Urinary excretion of diethylphosphorus metabolites in persons poisoned by quinalphos or chlorpyrifos

The urinary excretion rates of diethyl phosphate and diethyl phosphorothioate and changes in blood cholinesterase activities were studied in fifteen persons self-poisoned either by the organophosphorus pesticide quinalphos (twelve persons) or by chlorpyrifos (three persons). The organophosphate poisoning was always indicated by a significant depression of serum and/or red blood cell cholinesterase activities. The return of serum cholinesterase activity in the range of referent values took more than 30 days and had a different course in different persons. The most rapid increase in red blood cell acetylcholinesterase activity was noted within 24 h after the first treatment with oximes Pralidoxime and/or HI-6. None of the spot urine samples, collected daily after admission of persons to hospital, contained measurable quantities of the parent pesticide. There was no correlation between the maximum concentration of total urinary diethylphosphorus metabolites normalized to creatinine and the initial inhibition of blood cholinesterase activities measured in samples collected on the day of admission to hospital. The excretion of metabolites followed the kinetics of a biphasic reaction. The half-time of urinary metabolites concentration decrease in the fast excretion phase in quinalphos poisoned persons was 5.5–14.2 h (eight persons) and 26.8–53.6 h (four persons) and in chlorpyrifos poisoned persons 3.5–5.5 h. The half-time for the slow excretion phase ranged from 66.5 to 127.9 h in all persons and for both compounds. For a given person, the rates of excretion of diethyl phosphate and diethyl phosphorothioate were about the same. However, in quinalphos poisoned persons the proportions of single metabolites in total diethylphosphorus metabolites varied with the initial maximum concentration of total metabolites. Simultaneous determination of both metabolites gave a more reliable and sensitive confirmation of absorption and retention of quinalphos and chlorpyrifos in the body.

Chlorpyrifos metabolites in serum and urine of poisoned persons

Concentrations of parent pesticide and corresponding diethylphosphorus metabolites in blood serum and urine were investigated in persons who had ingested a concentrated solution of organophosphorus pesticide chlorpyrifos. The organophosphate poisoning was indicated by a significant depression of blood cholinesterase (EC 3.1.1.7 and EC 3.1.1.8) activities. Blood and spot urine samples were collected daily after admission of the persons to hospital. Chlorpyrifos was detected only in serum samples in a period up to 15 days after poisoning. In the same samples chlorpyrifos oxygen analogue, chlorpyrifos oxon, was not detected. The presence of diethylphosphorothioate in all serum and urine samples confirmed that part of chlorpyrifos was hydrolysed before its oxidation. The maximum concentrations of chlorpyrifos in serum and of metabolites in serum and urine were measured on the day of admission. The decrease in concentrations followed the first-order kinetics with the initial rate constant faster and the later one slower. In the faster elimination phase chlorpyrifos was eliminated from serum twice as fast (t1/2 = 1.1-3.3 h) as the total diethylphosphorus metabolites (t1/2 = 2.2-5.5 h). The total urinary diethylphosphorus metabolites in six chlorpyrifos poisoned persons were excreted with an average elimination half-time of 6.10 +/- 2.25 h (mean +/- S.D.) in the faster and of 80.35 +/- 25.8 h in the slower elimination phase.

Analysis of polychlorinated biphenyls, organochlorine pesticides and chlorophenols in rain and snow

Polychlorinated biphenyls (PCBs), organochlorine pesticides and chlorophenols were measured in samples of rain and snow collected at urban and suburban/semi-rural locations in the Zagreb City area, Croatia. PCBs and organochlorine pesticides were extracted with hexane from filtered aqueous samples and from particulate matter isolated by filtration. Chlorophenols were accumulated from rain and snow water by C18 reversed-phase adsorption. All samples were analysed by capillary gas chromatography using an electron-capture detector. Polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) in rain and snow water were checked by gas chromatographic–mass spectrometric analysis of combined hexane extracts. PCBs were detected in all water (<1–203 ng l–1) and particle (40–4155 ng g–1) samples. The only organochlorine pesticide present in all rain and snow water (1–36 ng l–1) and in particle (7–512 ng g–1) samples was γ-hexachlorocyclohexane as a consequence of the regular local usage of lindane. A positive correlation was found between its concentration in the water phase and the average air temperature during the sampling period. Compounds of the DDT-type, trace amounts of which were detected in only two rain water samples, were determined in most particle samples. The DDE : DDT median concentration ratio in particles was lower than unity and indicated a recent input of DDT into the atmosphere. The incidence and concentrations of di-, tri-, tetra- and pentachlorophenols were higher in snow (single compound concentration 11–527 ng l–1) than in rain (single compound concentration 2–171 ng l–1). A quadratic decrease in chlorophenol concentrations in snow and rain with increasing air temperature was observed. Trace amounts of PCDDs and PCDFs were detected in both rain and snow water samples and the highest concentrations were measured for octa-CDD (2 pg l–1 in snow and 6 pg l–1 in rain).

Diethylphosphorus metabolites in serum and urine of persons poisoned by phosalone

The presence and elimination rate of phosalone and its diethylphosphorus metabolites in blood serum and urine were studied in persons who had ingested a concentrated phosalone solution. Phosalone was detected only in serum samples. As it was rapidly hydrolysed and eliminated from the body, its diethylphosphorus metabolites were a more sensitive indicator of exposure. The concentration decrease of phosalone in serum and of total diethylphosphorus metabolites in serum and urine followed the kinetics of a biphasic reaction. The faster elimination half-times in serum, calculated for two persons, were 2.3 and 3.4 h for phosalone and 3.4 and 38.6 h for total diethylphosphorus metabolites. In the faster phase the average elimination half-time of total urinary metabolites in five persons was 25 +/- 17 h. The kinetic data for total urinary metabolites in a person occupationally exposed to phosalone indicated an early and very fast elimination phase (elimination half-time 1.3 h), which was overlooked in poisoned persons. The proportions of single metabolites in total urinary metabolites in poisoned persons depended on whether the total amount of diethylphosphorus metabolites was above 1000 or below 1000 nmol/mg creatinine. Diethylphosphorodithioate predominated at high and diethylphosphate at low concentrations of total metabolites. The correlation between the maximum concentrations of total metabolites, measured in urine of poisoned persons on the day of admission to hospital or a day later, and the initial depression of serum cholinesterase (EC 3.1.1.8) and erythrocyte acetylcholinesterase (EC 3.1.1.7) activities was poor (r = 0.6).

The metabolites of organophosphorus pesticides in urine as an indicator of occupational exposure

The differences in the degree in workers’ exposure to organophosphorus pesticides during the spraying of an apple‐orchard were assessed from the urinary content of metabolites: dimethyl phosphorothiolate potassium salt (DMPThK) for Demeton‐S‐methyl and dimethyl phosphorothionate and phosphorodithioate potassium salts (DMTPK and DMDTPK) for Azinphos‐methyl and Methidathion. The highest median concentrations of the metabolites in the urine samples collected after two to three days of work with the pesticides were determined in the mixers preparing pesticide solutions: DMPThK 83ng cm‐3 (N = 7) after exposure to Demeton‐S‐methyl; DMTPK 2040 and DMDTPK <20n gcm‐3 (N =7) after exposure to Azinphos‐methyl; DMTPK 501 and DMDTPK 88 ng cm‐3 (N = 6) after exposure to Methidathion. The applicators (sprayers) were the second most exposed group: DMPThK 30 ng cm‐3 (N = 6) after exposure to Demeton‐S‐methyl; DMTPK 433 and DMDTPK <20 ng cm‐3 (N = 7) after exposure to Azinphos‐methyl; DMTPK 45 and DMDTPK <20 ng cm‐3 (N = 1...

Sorption behaviour of some chlorophenols in natural sorbents. 1. Validity of the partition model for sorption of phenolates

Abstract In order to verify the validity of the partition model for describing the sorption behaviour of hydrophobic but ionizable polar compounds in natural sorbents, a series of experiments was carried out in which three chlorophenols: 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol, were sorbed in 14 different soil and sediment samples. Freundlich isotherm coefficients K f and 1 n were calculated for all three compounds in all sorbents and compared with those favouring phenolate forms. The sorption coefficients K f were closely related to the total sorbent organic matter content with a high correlation coefficient. However, isotherm non-linearities were observed in almost all experiments. The removal of the sorbent organic matter from the three tested sorbents drastically decreased the sorption intensity in two of them, but considerably increased it in the third, indicating that interaction with the mineral surface could be much stronger than sorption in the organic phase. These results indicate that the simplified partition concept used for the sorption of non-polar compounds might not offer an adequate description of the sorption behaviour of chlorophenolates in natural sorbents.

The rate of urinary excretion of phosalone residues in occupationally exposed persons

The absorption of malathion and phosalone was followed in occupationally exposed workers by determination of residues excreted in the urine. Because of the high concentrations found in the morning urine samples, the rates of excretion of phosalone metabolites in the urine of a volunteer experimentally exposed to phosalone during one and then again during three subsequent working days were investigated. The urinary excretion of phosalone metabolites was most intense 4--5 hours after exposure. At the beginning of the next day, the metabolites were still well measureable in the urine. Blood and plasma cholinesterase activities were only slightly reduced during exposure. The analyses of 24-hour urine samples, or of urine samples taken 4--5 hours after exposure, are not suitable for the routine control of occupationally exposed persons because of sampling difficulties. Instead, analyses of samples taken immediately before and after work hours have to be performed. A systematic increase in the concentrations of pesticide residues in the morning urine should initiate more efficient and well-timed protection measures.

Persistent organochlorine compounds in water and soil environments

Reviews compound physico‐chemical properties and water and soil properties influencing the transport and distribution of organochlorine pesticides, polychlorinated biphenyls (PCBs) and chlorophenols in a water and soil environment. As highly hydrophobic compounds of low water solubility, organochlorine pesticides and PCBs are rapidly and strongly sorbed by most soils and sediments. The sorption of weakly acidic chlorophenols comprises both molecular and ionic forms and depends not only on the soil/sediment organic matter content but also on the pH and ionic strength of the aqueous phase. Briefly describes the analytical methods for trace analysis of organocholorine pesticides, PCBs and chlorophenols in water and soil/sediment samples. Presents some results of those micropollutants’ analysis in surface, ground and drinking waters, soils, river sediments and wet depositions in Croatia.

Sorption behaviour of some organophosphorus pesticides in natural sediments

Sorption behaviour of four organophosphorus pesticides: demeton‐S‐methyl, methidathion, azinphosmethyl and phosalone, in two different pond sediments is reported. The sorption coefficients Kd in both sediments are found to follow the same sequence as the lipophilicity of the compounds expressed as their n‐octanol/water partition coefficients, Kow . The isotherms for demeton‐S‐methyl and methidathion are approximately linear in the concentration range studied, whereas nonlinear Freundlich isotherm with parameter 1/n significantly less than 1 better fits the experimental data for azinphos‐methyl and phosalone. The sorption efficiency for all the four pesticides is higher in the sediment with a lower content of organic matter. Isotherm nonlinearities and discrepancy between Kd values and the organic matter content of the sediments both indicate that a simple partition model does not offer indiscriminately an adequate visualization of the sorption behaviour. However, the sorption and partition results reporte...