[Evaluation of sources of mercury absorption through studying urinary mercury levels in the general population]

OBJECTIVES

The number of instances where mercury exposure is possible outside the workplace are numerous, with the main source being amalgam dental fillings and diet. It is also possible to envisage environmental exposure in subjects resident in areas where there is existing environmental contamination. This is probably what happened in Tuscany where past mining activity in the Monte Amiata area may have been the cause. This study estimated the concentration of urinary mercury (HgU) in non-occupationally exposed subjects from southern Tuscany, with the aim of evaluating the sources of mercury absorption in the general population.

METHODS

A questionnaire aimed at collecting specific information on factors which might influence the uptake of mercury was used. 164 subjects were studied: 82 subjects (41 males, 41 females) came from the Monte Amiata area and the other 82 (41 males, 41 females) from the Province of Siena. In this way it was possible to evaluate the elements associated with everyday life which may have influenced the presence of the metal in the urine. Since the distribution of the variables cannot be assumed multivariate normal as usual, a recently-proposed method based on a permutation procedure was adopted that allows the analysis of the variables as well as the single marginal analyses, without assuming any model for the distribution of variables.

RESULTS AND CONCLUSIONS

The results showed significantly lower levels of HgU in the subjects from the Monte Amiata area. Highly significant differences were demonstrated in the population which was sub-divided according to number and surfaces of amalgam fillings, use of contact lenses and type of water drunk (p < 0.001). Correlations between the levels of HgU and the investigated variables were not observed. It was confirmed that mercury uptake is simultaneously influenced by many factors. Probably the presence of higher levels of mercury in the environment in the Monte Amiata area is a factor of minor importance compared to others, especially the number of amalgam fillings, in determining mercury absorption in the general population.

[In vitro study of transcutaneous inorganic mercury absorption from solid soil]

OBJECTIVES

Skin is such an important route of absorption of mercury compounds that the ACGIH has assigned them a skin notation. Soil has been recognised as a potential source of exposure to chemical contaminants. It therefore seems advisable to establish maximum daily exposure levels for mercury in soil. In the past, areas adjacent to certain industries and smelters were heavily contaminated by mercury. For example, on Monte Amiata in Tuscany, which was an important mercury mining and production centre in the past, several areas have been polluted. To understand the dermal uptake of chemicals bound to soil and dust, information on the pure substance is helpful but does not seem sufficient. Other factors must be accounted for, that can easily be reproduced and controlled in in vitro experiments.

METHODS

Using an in vitro diffusion cell system and human skin, we studied percutaneous penetration of mercury chloride (HgCl2) at different concentrations, with particular emphasis on skin absorption from soil. The test apparatus consisted of a flow-through diffusion cell system. Dermotomed human cadaver skin was used as the membrane, while the receiving liquid was a saline solution with 6% PEG-20 oleyl-ether and gentamycin sulphate. Mercury chloride was applied at two different concentrations using a buffered solution and soil as vehicles.

RESULTS AND CONCLUSIONS

Increments of percentage of absorption at the different hours were found to be significantly lower in the cells where the higher concentration of mercury chloride was applied. In the receiving fluid of cells where soil was used as vehicle, the concentration of mercury was always below the detection limit. Skin contamination with soil containing inorganic mercury does not seem to be a dermal risk.

Dermal exposure assessment in occupational medicine

The importance of dermal exposure has increased during the last few years, mainly because of the reduction of respiratory exposure to toxicants. Pesticides, aromatic amines and polycyclic aromatic hydrocarbons are considered to be the chemicals at highest dermal risk. In the occupational exposure limit lists of the American Conference of Governmental Industrial Hygienists (ACGIH) and of many countries, compounds that can be absorbed through the skin are identified by a skin notation. However, a generally accepted criterion for assigning skin notation does not exist. The recent attempts to develop health-based dermal occupational exposure limits (DOELs) have not been accepted, thus in practice their use has remained limited. To predict the systemic risk associated with dermal exposure and to enable agencies to set safety standards, penetration data are needed. Moreover, there is a need for a practical risk assessment model, particularly for small and medium-sized enterprises.

[RISKOFDERM: European research project for assessment of occupational skin exposure to chemicals]

OBJECTIVES

RISKOFDERM is a research project whose aim is to develop instruments to assess and manage occupational dermal exposure to chemical substances.

METHODS

The research, funded by the European Commission, involves 15 Institutes from 10 member countries; it is a continuation of the Dermal Exposure Network experience and consists of four interrelated parts. The first phase (Qualitative survey) assumed that dermal exposure can be extrapolated from one compound to another when it is task-based: therefore six Dermal Exposure Operation units (DEOu) were defined that lead back to the variety of occupational dermal exposure conditions and an extensive Questionnaire was developed for on-site surveys to perform standard observations in selected working situations (scenarios).

RESULTS

The Italian group, participating in the research, obtained a set of observations relating to two "scenarios" in different working sectors: asphalt, ceramic and pottery workers, spectacle decorators and paint production: the aim was to verify the validity of the methodology in assessing the risk of percutaneous absorption, time, frequency and extension of skin exposure.

CONCLUSIONS

From the observations made it was shown that the perception of risk was poor; it is necessary to rationalise work organization, and train and inform the employees on the correct use of personal protection devices.

Some aspects of erythrocyte metabolism in insulin-treated diabetic dogs

Insulin-dependent diabetes mellitus (IDDM) is a common metabolic disease often complicated by a number of pathological conditions among which are haematological changes and alterations in blood cell function. Human and feline diabetes mellitus patients have been reported to be associated with oxidative stress that can lead to membrane alterations and to reduced erythrocyte life-span. Erythrocyte function in dogs affected by IDDM has been investigated during insulin therapy, paying attention to antioxidant status, membrane resistance, enzyme activities and 2,3-diphosphoglycerate (2,3DPG) concentration. Thirteen diabetic and 36 healthy dogs were bled and haematology and blood chemistry assays were performed to evaluate the degree of compensation. Osmotic fragility, the activities of the enzymes glucose-6-phosphate dehydrogenase (G6PD) and pyruvate-kinase (PK) and the concentrations of reduced glutathione (GSH) and 2,3DPG were evaluated in the erythrocytes. Diabetic dogs did not differ from controls in terms of haematological parameters, except for higher numbers of platelets. Higher values of fructosamine, glucose, protein, plasma potassium and calculated osmolality were detected in the plasma from diabetic dogs. No differences were detected in osmotic fragility, GSH concentration and PK activity between the two groups but 2,3DPG concentration and G6PD activity were statistically significantly higher in the diabetic group. The results indicate minimal alterations in erythrocyte functions occur in insulin-treated diabetic dogs. This contrasts with what has been reported for IDDM humans and cats.

Evaluation in vitro of canine neutrophil function

Polymorphonuclear granulocyte (PMN) phagocytosis may be affected by many pathological changes. A panel of tests requiring relatively small volumes of blood was applied to 16 healthy dogs in order to obtain normal values and to standardize techniques. PMNs were isolated by discontinuous Percoll gradients; chemotaxis was tested in a modified Boyden chamber using the leading front method; fluorescinated yeast uptake was evaluated on a slide and superoxide (SO) production and adherence was carried out on a microtitre plate. The different aspects of phagocytosis showed no correlation with one another. Better results were obtained using a 60 min incubation period using interleukin-8 (25 ng/mL) as an activator for chemotaxis, and incubating plates for 30 min with phorbol myristate acetate (10(-6)mol/L) to assess SO production.

Essential oils from Piper cernuum and Piper regnellii: antimicrobial activities and analysis by GC/MS and 13C-NMR

The essential oils of Piper cernuum and Piper regnellii leaves were analyzed by gas chromatography-mass spectrometry (GC-MS) and the results were compared to that obtained by means of a program designed to analyse (13)C-NMR data of complex mixtures. Bicyclogermacrene (21.88 %)/beta-caryophyllene (20.69 %) and myrcene (52.60 %)/linalool (15.89 %) were the major constituents in essential oil from leaves of P. cernuum and P. regnellii, respectively. Both essential oils presented growth inhibitory activities against Staphylococcus aureus and Candida albicans.

Asbestos exposure assessment by mineralogical analysis of bronchoalveolar lavage fluid

Mineralogical analysis of bronchoalveolar lavage fluid (BALF) by electron microscopy can represent the most suitable method for assessing asbestos exposure. However, it has been claimed that no standardized or systematic approach to the subject of mineralogical analysis exists. This study aimed to evaluate BALF mineralogical analysis by transmission electron microscopy as biomarker of asbestos fiber load. BALF was examined in 108 exposed workers and 57 patients who underwent diagnostic fiberoptic bronchoscopy for various clinical purposes. Asbestos bodies in BALF were counted with a phase-contrast microscope. Fibers were counted and analyzed by transmission electron microscopy, which showed a significant difference between the two populations and positive results for all exposed subjects. Only 82.2% of the exposed population tested positive for asbestos bodies. Subjects with long-term exposure had higher concentrations of fibers than did those with more recent exposure, probably because of the higher workplace exposure levels in the past. The results of the study confirm that fiber concentration in BALF can be considered as a reliable biomarker of past asbestos exposure, even many years after the end of exposure.

Dermal exposure assessment of polycyclic aromatic hydrocarbons: in vitro percutaneous penetration from coal dust

To understand the dermal uptake of chemicals bound to soil and dust, information on the neat substance is helpful but does not seem sufficient. Because of its content of polycyclic aromatic hydrocarbons (PAHs) coal is suspected to be carcinogenic. However, experimental carcinogenity studies on coal dust never succeeded in demonstrating a higher incidence of cancer in treated animals. The aim of the study was to assess dermal penetration through human skin of PAHs from coal dust. A sample of coal dust was grinded and sieved, using the particle size of < 30 microm. An in vitro static diffusion cell system validated by in vitrolin vivo comparison has been used to study dermal penetration through human skin of PAHs from coal dust compared with their percutaneous absorption as pure compounds. No percutaneous penetration of PAHs was observed in the cells where coal dust was applied, while dermal penetration was demonstrated for PAHs applied in an acetone solution. Results agree with the literature that PAHs are poorly absorbed through the skin from solids. Dermal risk assessment of PAHs should take into account not only the degree and the extent of skin contamination, but also their bioavailability, which is heavily influenced by the physico-chemical characteristics of the matrix.

Phenylpropanoids and tetrahydrofuran lignans from Piper solmsianum

A tetrahydrofuran lignan as well as the known tetrahydrofuran lignan, (-)-grandisin, and five phenylpropanoid derivatives were isolated from Piper solmsianum. Their structures were determined by means of spectral analyses, including 2D NMR techniques such as NOE-DIFF and HMBC 3J(C-H).

Phenylpropanoid derivatives and biflavones at different stages of differentiation and development of Araucaria angustifolia

Chemical investigations carried out with tissues at different developmental stages of Araucaria angustifolia established the presence of E and Z isomers of octadecyl p-coumarate and octadecyl ferulate in undifferentiated callus; in the seedling stems, the source of explants, three biflavones of the amentoflavone-type were isolated, whereas the diterpene, trans-communic acid, was obtained from the seedling roots. Adult stems accumulated the benzaldehydes, vanillin, p-hydroxybenzaldehyde and coniferaldehyde; the lignans, pinoresinol, eudesmin and lariciresinol; and the isoflavones, cabreuvine and irisolidone.

Characteristics of the response of ovine granulocytes (PMNs) to zymosan-activated serum (ZAS) and to recombinant human interleukin-8 (IL-8)

The chemotactic activity of zymosan-activated serum (ZAS) and of two concentrations of recombinant human IL-8 (IL-8(25), 25 ng/ml; IL-8(50), 50 ng/ml) for ovine polymorphonuclear granulocytes (PMNs) was tested in a modified Boyden chamber. Thick cellulose acetate filters and the leading front method were used to quantify the movements of the cells. Both ZAS and IL-8(25) exerted a chemotactic effect on ovine PMNs (P < 0.01): IL-8(50) induced a more homogeneous response (P < 0.001). To verify the characteristics of the responsiveness to the chemokines after short-term (st) or long-term (lt) repeated samplings, chemotaxis was investigated 1 (T1st), 2 (T2st), 24 (T3st) and 48 h (T4st) after the basal sampling (T0st) and 15 days (T1lt) after the basal sampling (T0lt). No differences in chemotaxis were found in long-term repeated samplings. In contrast an increase in the responsiveness to IL-8(25) and to IL-8(50) (P < 0.05) was detected at T2st in comparison with T0st. Furthermore, the significance of the distance run by activated PMNs compared with the controls, increased from T0st to T2st, as a sign of a more homogeneous response to the chemokines. In the absence of evident changes in circulating leucocyte numbers and in serum cortisol concentrations, these findings could be interpreted as a consequence of a different expression of chemoattractant receptors on the membrane of PMNs collected at different times.

[Dermal risk assessment in occupational medicine]

The importance of dermal exposure has increased during the last few years mainly because of the reduction of respiratory exposure to toxicants. Pesticides, aromatic amines and polycyclic aromatic hydrocarbons are considered to be the chemicals with highest dermal risk. In the occupational exposure limit lists of the ACGIH and of many countries compounds that can be absorbed through the skin are identified by a skin notation. Usually the skin notation indicates that the percutaneous absorption of the chemical can contribute to the body burden. However, a generally accepted criterion for assigning skin notation does not exist. When it is possible to make standardized measurements of dermal exposure, it will be possible to develop Dermal Occupational Exposure Limits (DOEL) with which such measurements can be compared to enable a regulatory approach in the risk assessment field. However, the recent attempts to develop health-based DOELs have not been accepted, thus in practice their use has been limited.

Non-specific immunity and ketone bodies. II: In vitro studies on adherence and superoxide anion production in ovine neutrophils

The effects of the ketone bodies beta-OH-butyrate and acetoacetate (2.4 or 4.8 mmol/l), administered singly or simultaneously in vitro, on adherence and superoxide anion (SO) production in ovine neutrophils were investigated by simultaneous assay in 96-well microplates. Because the acetoacetate used was a lithium salt, the effect of 2.4 and 4.8 mmol/l lithium chloride was also tested. Neutrophils from eight non-lactating, non-pregnant ewes were used. SO release from neutrophils was found to be very low in basal conditions and was apparently not stimulated by contact with plastic. Administration of 10(-7) mol/l phorbol myristate acetate (PMA) caused a rapid increase and release of SO production, but smaller than that induced by co-stimulation with plastic and 10(-7) mol/l PMA. LiCl (2.4 and 4.8 mmol/l) significantly increased PMA-stimulated release, but inhibited plastic and PMA co-stimulated SO release. Administration of 2.4 mmol/l ketone bodies inhibited plastic and PMA-costimulated SO release, but the effect of acetoacetate could be due to the lithium component. Administration of 4.8 mmol/l ketone bodies had no effect. Adherence was significantly increased by contact with plastic, and moreover by 10(-7) mol/l PMA. The effect was similar when PMA was acting alone or with plastic. Neither basal nor stimulated adherence were affected by 2.4 or 4.8 mmol/l ketone bodies. LiCl at a concentration of 4.8 mmol/l increased PMA and plastic co-stimulated adherence. The results suggest that, in sheep, only the ketone body beta-OH butyrate at concentrations seen in mild ketosis, could decrease bactericidal activity, while adherence is not affected. In addition to other factors that could impair the efficiency of the immune system in ketotic ruminants, the reduced bactericidal activity may contribute to the higher occurrence of infectious disease in these animals.

Percutaneous penetration studies for risk assessment

During the last few years the general interest in the percutaneous absorption of chemicals has increased. It is generally accepted that there is very few reliable quantitative and qualitative data on dermal exposure to chemicals in the general population and in occupationally exposed workers. In order to predict the systemic risk of dermally absorbed chemicals and to enable agencies to set safety standards, data is needed on the rates of percutaneous penetration of important chemicals. Standardization of in vitro tests and comparison of their results with the in vivo data could produce internationally accepted penetration rates and/or absorption percentages very useful for regulatory toxicology. The work of the Percutaneous Penetration Subgroup of EC Dermal Exposure Network has been focussed on the standardization and validation of in vitro experiments, necessary to obtain internationally accepted penetration rates for regulatory purposes. The members of the Subgroup analyzed the guidelines on percutaneous penetration in vitro studies presented by various organizations and suggested a standardization of in vitro models for percutaneous penetration taking into account their individual experiences, literature data and guidelines already in existence. During the meetings of Percutaneous Penetration Subgroup they presented a number of short papers of up to date information on the key issues. The objective was to focus the existing knowledge and the gaps in the knowledge in the field of percutaneous penetration. This paper is an outcome of the meetings of the Percutaneous Penetration Subgroup and reports the presentations on the key issues identified throughout the 3-year duration of the Dermal Exposure Network (1997-1999).

Dermal route in systemic exposure

To evaluate risk from dermal exposure, the amount of material on the skin must first be measured. The potential for dermal uptake must then be assessed for the potential health effects from systemic exposure. No standard methods exist for studying these processes, and published data are not comparable because of the different techniques used. Future validated methodology should provide a sound scientific basis for risk assessment. Methods for measuring skin and surface contamination will require development of reference contaminated surfaces and skin as part of quality control procedures. Biological monitoring is a valuable tool in the assessment of dermal absorption, in contributing to the validation of in vitro techniques, and in risk assessment and management. It will be necessary to conduct detailed investigations to support risk assessment for dermal exposure. Ultimately, predictive models will be established for exposure and for dermal absorption to support a generic approach and allow risk assessment strategies appropriate to actual workplace situations.

Non-specific immunity and ketone bodies. I: In vitro studies on chemotaxis and phagocytosis in ovine neutrophils

The in vitro effects of the ketone bodies beta-OH-butyrate (2.4 or 4.8 mmol/l) and acetoacetate (2.4 or 4.8 mmol/l) on the uptake of latex particles (1.09 microns) and chemotaxis were investigated in ovine neutrophils. Because the acetoacetate used was a lithium salt, the effect of 2.4 or 4.8 mmol/l lithium chloride was also tested. Neutrophils from eight non-lactating, non-pregnant ewes were studied. The uptake of latex particles, as measured by a spectrophotometric method, showed wide individual variation. The phagocytotic activity was unaffected by 2.4 mmol/l ketone bodies and LiCl, but it was significantly inhibited by 4.8 mmol/l beta-OH-butyrate and activated by 4.8 mmol/l LiCl. The latter result could be masking an inhibitory effect of acetoacetate. Chemotactic movements of neutrophils, as evaluated in a modified Boyden chamber using homologous zymosan-activated serum (ZAS) as a chemoattractant, were slightly but significantly reduced by a 2.4 mmolar concentration of the ketone bodies, administered singly or simultaneously, and by LiCl. We conclude therefore that the inhibitory effect of lithium-acetoacetate could be due to its lithium component. The 4.8 mmol/l dose of acetoacetate and beta-OH butyrate significantly decreased chemotaxis only when both compounds were added simultaneously. No effect of 4.8 mmol/l LiCl was observed. These results suggest that ketone bodies, in particular beta-OH butyrate, could directly influence particle uptake and chemotaxis in neutrophils. Although other factors could decrease the efficiency of the immune system in ketotic ruminants, the effects of the ketone bodies on neutrophils functions may explain the high frequency of infectious disease during 'ketotic syndrome'. The immunomodulatory effect of lithium needs to be evaluated further and it should be considered when testing lithium compounds.

Dermal exposure assessment of polycyclic aromatic hydrocarbons: in vitro percutaneous penetration from lubricating oil

OBJECTIVES

Percutaneous penetration of polycyclic aromatic hydrocarbons (PAHs) is affected by various factors connected to exposure conditions. The nature of the matrix, such as that of oil, can strongly affect their percutaneous penetration. Risk assessment should consider these effects. We examined the effect of matrix on percutaneous penetration of PAHs, particularly that of lubricating oil.

METHODS

The test apparatus consisted of an in vitro static diffusion cell system using full-thickness monkey (Cercopithecus aetiops) skin as the membrane and saline solution with gentamycin sulfate and 4% bovine serum albumin as receptor fluid. Chemical analysis of PAHs in the samples obtained from cells was carried out by inverse-phase HPCL, and the results were read by spectrofluorimetry.

RESULTS

Comparing the penetration of 13 PAHs from a lubricating oil and from acetone solution with artificial sweat resulted in a significantly slower passage from the oil matrix for acenaphthene, anthracene, phenanthrene, fluoranthene, naphthalene, pyrene, fluorene (Mann-Whitney U test, P < 0.05). No significant differences in the passage were found for chrysene because, in the test with oil, its concentration was very often below the detection limit. For benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[a]pyrene it was possible to demonstrate a passage through the skin only when compounds were applied in acetone solution with artificial sweat.

CONCLUSIONS

The results of the study suggest the necessity of dermal penetration data relevant for risk assessment, obtained under experimental conditions similar to the real exposure conditions.

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.

[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.

Metabolic findings in the erythrocytes of cardiopathic and anaemic dogs

Few data are available on the activities of canine erythrocyte enzymes and on 2,3 diphosphoglycerate (2,3DPG) concentrations in pathological conditions other than heritable erythrocyte defects. Because some diseases might affect erythrocyte metabolism and oxygen transport, we evaluated these parameters in 10 healthy dogs and in dogs with symptomless dirofilariosis (n = 9), mild (n = 13) and severe (n = 8) cardiac failure, and haemolytic anaemia (n = 8). To evaluate possible membrane damage, the osmotic fragility of the red cells was measured. No haematological abnormalities were found in the dogs with mild cardiopathy or in those with symptomless dirofilariosis. Severe anaemia and neutrophilic leucocytosis were found in the dogs with haemolytic anaemia and, to a lesser degree, in those with severe heart failure. In dogs with these two diseases, elevated values obtained were, respectively: pyruvate kinase (PK) 17.5 +/- 10.3 U/g haemoglobin (Hb) (P < 0.001) and 11.6 +/- 7.5 U/g Hb (P < 0.01); glucose-6-phosphate dehydrogenase (G6PDH) 8.9 +/- 5.4 U/g Hb (P < 0.001) and 5.6 +/- 4.2 U/g Hb; 2,3DPG 21.8 +/- 4.9 U/g Hb (P < 0.001) and 22.5 +/- 4.1 U/g Hb (P < 0.001). The increased 2,3DPG concentrations may have been due to diminished oxygen availability but the observed enzymatic changes were attributed mainly to the presence of young red blood cells: there was a positive correlation between nucleated red blood cells and PK activity, G6PDH activity and 2,3DPG concentration and a negative correlation between mature erythrocytes and PK activity, G6PDH activity and 2,3DPG concentration. This was supported by the derivative curve of the fragiligram, which showed two or three peaks corresponding to different erythrocyte populations and by the negative correlation between the maximum haemolytic NaCl concentration and the reticulocyte number. The measurement of PK and G6PDH activity and of the 2,3PG concentration, together with information provided by the fragiligram, would seem to be of value in defining the clinico-haematological picture in clinical heart diseases and haemolytic anaemia.