External and internal exposure of wine growers spraying methyl parathion.

Organophosphates, used in agriculture, are readily absorbed through the skin. We investigated the relationship between dermal and inhalative methyl parathion exposure and the plasma levels. Twenty-three healthy wine growers sprayed the insecticide for 50 min. Fluorescent brilliant sulfoflavin was added to the spraying fluids and filter papers were fixed on the subjects. The filter papers were used to evaluate the amount of brilliant sulfoflavine on the unprotected skin fluorometrically. Inhalative exposure was measured with personal air sampler. Plasma concentrations of methyl parathion and its metabolite methyl paraoxon were determined with gas chromatography. Cholinesterase activity in serum and erythrocytes was measured before and after exposure. Some wine growers wore protective clothes, none protective gloves. Dermal exposure ranged up to 12,044 microg, inhalative to 22 microg. Maximum plasma concentration of methyl parathion was 12.1 microg/l. Methyl paraoxon was not detectable. Cholinesterase activity did not decrease. Dermal exposure correlated with the methyl parathion plasma level (Spearman's rho=0.72, p<0.001). In conclusion, dermal exposure exceeded inhalative exposure considerably. Measuring dermal deposition with the brilliant sulfoflavin technique may provide a good estimate of the internal load with methyl parathion. Preventive measures should be improved as toxic effects of repeated exposure to low doses of methyl parathion cannot be excluded.

Compensation for unfavorable characteristics of irregular individual shift rotas.

Some employees of TV companies, such as those who produce remote TV programs, have to cope with very irregular rotas and many short-term schedule deviations. Many of these employees complain about the negative effects of such on their wellbeing and private life. Therefore, a working group of employers, council representatives, and researchers developed a so-called bonus system. Based on the criteria of the BESIAK system, the following list of criteria for the ergonomic assessment of irregular shift systems was developed: proportion of night hours worked between 22 : 00 and 01 : 00 h and between 06 : 00 and 07 : 00 h, proportion of night hours worked between 01 : 00 and 06 : 00 h, number of successive night shifts, number of successive working days, number of shifts longer than 9 h, proportion of phase advances, off hours on weekends, work hours between 17 : 00 and 23 : 00 h from Monday to Friday, number of working days with leisure time at remote places, and sudden deviations from the planned shift rota. Each individual rota was evaluated in retrospect. If pre-defined thresholds of criteria were surpassed, bonus points were added to the worker's account. In general, more bonus points add up to more free time. Only in particular cases was monetary compensation possible for some criteria. The bonus point system, which was implemented in the year 2002 for about 850 employees of the TV company, has the advantages of more transparency concerning the unfavorable characteristics of working-time arrangements, incentive for superiors to design "good" rosters that avoid the bonus point thresholds (to reduce costs), positive short-term effects on the employee social life, and expected positive long-term effects on the employee health. In general, the most promising approach to cope with the problems of shift workers in irregular and flexible shift systems seems to be to increase their influence on the arrangement of working times. If this is not possible, bonus point systems may help to achieve greater transparency and fairness in the distribution of unfavorable working-time arrangements within a team, and even reduce the unnecessary unfavorable aspects of shift systems.

Acute effects of low doses of methyl parathion on human EEG.

Biological monitoring of workers exposed to organophosphates consists mainly of measuring serum or erythrocyte cholinesterase activity. However, animal experiments and a field study suggest that quantitative analysis of EEG may be more sensitive. In a parallel group design, 25 farmers were investigated, spraying methyl parathion or water for 50min. EEG was recorded before and after spraying. Serum and erythrocyte cholinesterase activity was compared with intraindividual pre-exposure values. Plasma methyl parathion concentrations ranged up to 12.1µg/l, methyl paraoxon was not detectable. Based on plasma concentrations, two exposed subgroups were defined. In EEG recorded with closed eyes, α(1)-power increased insignificantly (Kruskal-Wallis test) in both subgroups. ß(1)-power was enhanced in both exposed subgroups, reaching significance (p≤0.05) at five of 17 electrodes. Spearman's rank correlation showed a significant association between methyl parathion plasma concentration and the median of ß(1)-band power of the 17 electrodes (rho=0.48, p=0.015). Cholinesterase activity did not decrease. On a group basis, EEG is possibly more sensitive than cholinesterase. EEG changes suggest brain cholinesterase inhibition following low exposure to methyl parathion.

Acute exposure to 50ppm toluene does not increase sleepiness.

The Pupillographic Sleepiness Test (PST) is a new neurophysiological method to assess sleepiness. In an exposure study to a constant exposure level of 50ppm toluene on 20 healthy men, our aim was to find out, if increased sleepiness could be seen with PST. PST was performed before and after 4.5h of exposure. General complaints were assessed with the Swedish Performance Evaluation System (SPES) self-assessment questionnaire, once before and during exposure. Values obtained during exposure were related to pre-exposure values. Parametric cross-over analysis of logarithmic Pupillary Unrest Index (PUI) values did not show an effect of toluene exposure. In a nonparametric cross-over analysis of SPES-scores a significant increase of the scores of unpleasant smell and irritation to the throat, but not of tiredness was found. In conclusion, acute exposure to 50ppm toluene, corresponding to the German threshold limit value, did not increase sleepiness.

Occupational exposure to heavy metals: DNA damage induction and DNA repair inhibition prove co-exposures to cadmium, cobalt and lead as more dangerous than hitherto expected.

Co-exposure to cadmium, cobalt, lead and other heavy metals occurs in many occupational settings, such as pigment and batteries production, galvanization and recycling of electric tools. However, little is known about interactions between several heavy metals. In the present study we determined DNA single strand break (DNA-SSB) induction and repair capacity for 8-oxoguanine in mononuclear blood cells of 78 individuals co-exposed to cadmium (range of concentrations in air: 0.05-138.00 micro g/m(3)), cobalt (range: 0-10 micro g/m(3)) and lead (range: 0-125 micro g/m(3)). Exposure to heavy metals was determined in air, blood and urine. Non-parametric correlation analysis showed a correlation between cadmium concentrations in air with DNA-SSB (P = 0.001, R = 0.371). Surprisingly, cobalt air concentrations correlated even better (P < 0.001, R = 0.401), whereas lead did not correlate with DNA-SSB. Logistic regression analysis including 11 possible parameters of influence resulted in a model showing that cobalt in air, cadmium in air, cadmium in blood and lead in blood influence the level of DNA-SSB. The positive result with cobalt was surprising, since exposure levels were much lower compared with the TRK-value of 100 micro g/m(3). To examine, whether the positive result with cobalt is stable, we applied several logistic regression models with two blocks, where all factors except cobalt were considered preferentially. All strategies resulted in the model described above. Logistic regression analysis considering also all possible interactions between the relevant parameters of influence finally resulted in the following model: Odds ratio = 1.286(Co in air) x 1.040(Cd in air) x 3.111(Cd in blood) x 0.861(Pb in air) x 1.023(Co in air x Pb in air). This model correctly predicts an increased level of DNA-SSB in 91% of the subjects in our study. One conclusion from this model is the existence of more than multiplicative effects for co-exposures of cadmium, cobalt and lead. For instance increasing lead air concentrations from 1.6 to 50 micro g/m(3) in the presence of constant exposures to cobalt and cadmium (8 micro g/m(3) and 3.8 micro g/m(3)) leads to an almost 5-fold increase in the odds ratio, although lead alone does not increase DNA-SSB. The mechanism behind these interactions might be repair inhibition of oxidative DNA damage, since a decrease in repair capacity will increase susceptibility to reactive oxygen species generated by cadmium or cobalt. Indeed, repair of 8-oxoguanine decreased with increasing exposures and inversely correlated with the level of DNA-SSB (P = 0.001, R = -0.427). Protein expression patterns of individuals exposed to cobalt concentrations of approximately 10 micro g/m(3) were compared with those of unexposed individuals using two-dimensional gel electrophoresis. Qualitative and apparent quantitative alterations in protein expression were selective and certainly occurred in <0.1% of all proteins. In conclusion, the hazard due to cobalt exposure - that has been classified only as IIB by the IARC - seems to be underestimated, especially when individuals are co-exposed to cadmium or lead. Co-exposure may cause genotoxic effects, even if the concentrations of individual heavy metals do not exceed TRK-values.

No influence of magnetic fields on cell cycle progression using conditions relevant for patients during MRI.

The purpose of this study was to examine whether exposure to magnetic fields (MFs) relevant for magnetic resonance imaging (MRI) in clinical routine influences cell cycle progression in two tumor cell lines in vitro. HL60 and EA2 cells were exposed to four types of MFs: (i) static MF of 1.5 and 7.05 T, (ii) extremely low frequency magnetic gradient fields (ELFMGFs) with +/- 10 mT/m and 100 Hz, as well as +/- 100 mT/m and 100 Hz, (iii) pulsed high frequency MF in the radiofrequency (RF) range (63.6 MHz, 5.8 microT), and (iv) a combination of (i-iii). Exposure periods ranged from 1 to 24 h. Cell cycle distribution (G(0)/G(1), S, and G(2)/M phases) was analyzed by flow cytometry. Cell cycle analysis did not reveal differences between the exposed and the control cells. As expected, positive controls with irradiated (8 Gy) HL60 and EA2 cells showed a strong G(2)/M arrest. Using conditions that are relevant for patients during MRI, no influence of MFs on cell cycle progression was observed in these cell lines. Care was taken to control secondary parameters of influence, such as vibration by the MR scanner or temperature to avoid false positive results.