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H Valentin

Publications and source records attributed to H Valentin.

At least 55 records · Page 3Linked to original sources
PubMed1984

[Neurotoxicity of chemical substances in the workplace. VI. Longitudinal study of persons occupationally exposed to mercury].

A longitudinal study was performed on eleven persons, who had been chronically exposed to mercury (Hg) (3 to 31 years, median 5 years) in 1977, 1980 resp., and 1982. During their work in a chemical plant they had had contact to elemental Hg and various inorganic as well as organic mercury compounds. The main purpose of the investigation was the evaluation of possible adverse effects to the nervous system caused by mercury. The internal Hg-exposure was measured by mercury analysis in blood (Hg-B) and in urine (Hg-U). Furthermore "time-weighted average" levels were calculated on the basis of former Hg-determinations from 1974 to 1982. For Hg-B these values ranged between 26 and 104 microgram/dl (median 42 microgram/l) and for Hg-U between 73 and 434 microgram/g creatinine (median 233 microgram/g creatinine) (upper normal levels: Hg-B: 5 microgram/l; Hg-U: 5 microgram/g creatinine). The determination of the peripheral nerve conduction velocities (NLG) of motor and sensory fibers as well as the registration of somatosensory-evoked potentials (SEP) revealed no pathological results, except one borderline case. The NLG- and SEP-values did not significantly differ from those of non exposed persons or from those of former NLG-determinations. No correlations were found between indicators of Hg-exposure and neurophysiological parameters regarding dose-effect-relationship. Statistical differences resulted in the time-dependent test of the psychological test battery performed in comparison to age-matched control persons of equal socio-economous status. In additional, significant relationships were calculated between Hg-exposure and these tests. Considering the inter- and intraindividual variations of the psychological test results, there were no substantial alterations in the total findings over the observed period except for one case. Workers with Hg-exposure below the current BAT-values (Hg-B 50 microgram/l, Hg-U 200 microgram/l) showed no pathological findings in the neurological, neurophysiological and neuropsychological examinations.

Adult↗
PubMed1984

Investigations on neurotoxicity of chemical substances at the workplace. V. Determination of the motor and sensory nerve conduction velocity in persons occupationally exposed to lead.

A cross-sectional study was performed in order to investigate the influence of chronic lead-exposure on the peripheral nervous system. We examined 148 male workers of a storage battery manufacturing plant, who had been exposed to lead metal and inorganic lead compounds for 1 to 28 years (mean 11 years). Fifteen workers with non-occupational risks of peripheral neuropathy (former diseases, alcohol abuse, medication) were excluded from the study. The investigation program comprised: case history, physical examination, analyses of blood- and urine-samples and determination of maximal motor, mixed and sensory conduction velocity (NCV) of the ulnar and median nerve of the right forearm. Objectively no worker showed any signs of health effects related to lead exposure. The "Biological Monitoring" included the determination of (1) Blood-lead level (Pb-B), (2) Free erythrocyte porphyrins (FEP), (3) delta-Aminolevulinic acid dehydratase (ALA-D) and (4) delta-Aminolevulinic acid in urine (ALA-U). Further "time-weighted-average (TWA)"-values of Pb-B were calculated on the basis of several determinations over the period 1975-1981. The following "actual" ("TWA") median values resulted: Pb-B 53 micrograms/dl (54 micrograms/dl), ALA-U 5.6 mg/l (8.4 mg/l), FEP 2.0 mg/l (2.0 mg/l). The "Biologischer Arbeitsstoff Toleranz Wert (BAT)" of 70 micrograms/dl for Pb-B was exceeded in 15 workers (11%), and of 15 mg/l for ALA-U in 30 cases (23%). In comparison with age-matched controls, the lead workers showed a mild slowing of NCV with mean values between 0.8 and 2.0 m/s. Multiple stepwise regression analyses revealed statistically significant correlations between the four NCV and age as well as Pb-B. There were better correlations by using "TWA" than "actual" data of Pb-B. Consideration of the results of the regression analyses, together with an evaluation of the individual neurophysiological status as a function of internal lead exposure, a "dose-effect-relationship" was found only in the case of Pb-B exceeding 70 micrograms/dl. From our study it is concluded that chronic lead exposure resulting in blood-lead levels of below 70 micrograms/dl is no occupational risk causing a functionally significant slowing of nerve conduction velocities.

Adult↗
PubMed1984

Medical and toxicological aspects of occupational nickel exposure in the Federal Republic of Germany--clinical results (carcinogenicity, sensitization) and preventive measures (biological monitoring).

In recent years reports on nickel-related diseases in the Federal Republic of Germany have been increasingly frequent. As a result, medical scientific institutions were called upon to clarify both the occupational medical and clinical, as well as the toxicological aspects of the situation. The main clinical finding was the increased incidence of malignant neoplasias in the respiratory tracts, in particular after many years of nickel exposure in refineries. Between 1967 and 1981, seven malignant neoplasms were legally recognized as occupation-related. Additionally, in the last two years, the existence of nickel-induced malignant neoplasms has been suspected in 16 cases, and the statutory procedure for the recognition of occupational diseases instituted. Our overview presents occupational-medical and clinical aspects. Among allergic nickel-induced conditions, eczematous skin diseases predominate. In addition, case reports of asthma have been published. Statistical evaluations showed that up to 17% of all occupational allergies may be related to occupational exposure to nickel. In this situation, preventive measure are of particular importance. To estimate exposure levels, both the measurement of the agent at the workplace and the quantitative determination of nickel in biological material can be used. The measurement of nickel excretion by the kidney has proved particularly useful in occupational medicine. In addition to clinical surveillance, it is recommended that this measurement should be performed on exposed persons at regular intervals.

Adult↗
PubMed1984

[Cadmium content of whole blood of inhabitants from various regions of Bavaria].

The blood Cd-concentration of 670 inhabitants of cities and rural districts (386 children, 175 men and 109 women) was measured by electrothermal atomic absorption spectrometry. The cadmium levels ranged from 0.3 micrograms Cd/1 to 7.3 micrograms Cd/1 blood with a median value of 0.9 micrograms Cd/1. Splitting up the whole collective according to the different living areas, the inhabitants of München, Neustadt and Nürnberg suburbs showed medians between 0.8 and 0.9 micrograms Cd/l blood. Higher medians (1.4 and 1.2 micrograms/l blood) have been calculated for the people living in Weiden and Nürnberg central area. The measured levels and medians correspond with the results of the newer national and international literature. There is no correlation of cadmium levels in blood and age or sex. The median for non smoking women and for children comes to 0.9 and for non smoking men to 0.8 micrograms Cd/l blood. The cadmium concentrations in blood are significantly higher in smokers than in nonsmokers. The group of nonsmokers shows a median of 0.9 micrograms Cd/l, for smokers consuming 20 cigarettes or less a day there is a median of 1.7 micrograms Cd/l while the group smoking more than 20 cigarettes a day has a median value of 2.50 micrograms Cd/l. Except one value all levels higher than 2.50 micrograms Cd/l belong to the group of smokers. The feasibility of blood cadmium analysis for biological screening of population with regard to environmental exposure is discussed.

Adult↗
PubMed1984

[Nickel and chromium content of selected human organs and body fluids].

Nickel and chromium analyses were performed in lung and kidney as well as in blood and urine samples of 45 autopsies from northern Bavaria area. The analyses were carried out with electrothermal atomic absorption after wet oxidative digestion. Median metal concentrations in blood were 4.5 micrograms Ni/kg resp. 2.8 micrograms Cr/kg, in urine 2.7 micrograms Ni/kg resp. 4.9 micrograms Cr/kg. The calculated values agree with the metal levels given in the new literature. Median metal concentrations in lung tissue were 7.4 micrograms Ni/kg resp. 36.5 micrograms Cr/kg; in the kidneys medians of 13.9 micrograms Ni/kg resp. 9.6 micrograms Cr/kg are found. In the literature only a few values for comparison are given. The metal concentrations in the different samples were not influenced by age or sex.

Adult↗
PubMed1983

[Neurotoxicity of workplace substances. IV. Determination of motor and sensory nerve conduction velocity in persons exposed to solvent mixtures].

A cross-sectional study was performed on 112 workers with long-term exposure (mean 5 years) to a mixture of organic solvents (aliphatic and aromatic hydrocarbons, halogenated hydrocarbons). The purpose of the study was to examine whether this exposure had caused impairment of the peripheral nervous function. Forty-six workers with non-occupational risk of peripheral neuropathy (previous diseases, alcohol abuse, medication) were excluded. As a basis for the evaluation of solvent exposure, we carried out "environmental and biological monitoring" for some solvents. In no case did a hint of a manifest disorder of the nervous system exist. By comparison with age-matched controls, the mean sensory conduction velocity (NCV) of the N. ulnaris of the exposed persons was significantly reduced by 1.5 m/s. The maximal motor NCV of the N. ulnaris and the sensory NCV of the N. medianus did not differ significantly. The differentiation of the workers relating to short-(7-24 months), middle-(25-60 months)- and long-(more than 60 months) term exposure showed that the sensory NCV of the N. ulnaris was slowed only for persons with middle- and long-term histories of solvent exposure. Assessing the individual neurophysiological status the frequency of pathological NCV improved from 12 to 36% in relation to increasing time of exposure. Overall 15 of 66 workers (23%) had abnormal NCVs. The findings are discussed according to data given in literature.

Humans↗
PubMed1983

[Pulmonary fibrosis caused by hard-metal dusts].

Hardmetals are broadly used in many different branches. In the FRG lung fibrosis caused by hardmetal-dust are recognized as occupational diseases (no. 4107). New findings concerning pathogenesis of this disease should be considered. Not only the dust of the presintered material is hazardous but also the inhalation of the sintered material. There is a special risk for tool-grinders. Cobalt is suspected to be the causal agent. In tool-grinders an elevated external and internal Cobalt-burden has been objectified. We report about 14 persons who suffered from lung fibrosis and worked in the hard metal industry. X-ray and pathohistological examinations may give some hints but there is no specific histological correlate. So the notifying procedure may be difficult. For this reason any case of aetiologically unknown lung fibrosis the lung biopsy and quantitative chemical analysis using AAS should be performed. In one patient the Cobalt-level in lung-tissue was significantly elevated. Toleration of invasive diagnostic measurements can not be demanded. Tool-grinders need more medical surveillance in future. As a preventive strategy the cobalt-exposure is to be reduced to a minimum. The external cobalt-burden at work-place can be estimated by the determination of the renal Cobalt-excretion.

Adult↗
PubMed1982

[Investigations on neurotoxicity of chemical substances at the workplace. III. Determination of the motor and sensory nerve conduction velocity in persons occupationally exposed to trichloroethylene].

We studied 31 employees (26 men, five women) from three firms, between the ages of 16 and 56 years, who had been exposed to trichloroethylene (TRI) from 1 month to 35 years, mean 7 years. To objectify the actual solvent-exposure we performed "biological monitoring" and determined TRI- and the metabolites trichloroethanol (TCE) and trichloroacetic acid (TCA) in blood- and/or urine-samples. The following concentrations were found in the urine-samples: TCE 19.0-357.0 mg/g creatinine, median 90.0; TCA 2.0-201.0 mg/g creatinine, median 48.0; TTC (TCE + TCA) 31.0-416.0 mg/g creatinine, median 112.5. Additionally three results of former urine-analyses in the period 1978-1980 from 10 workers were obtained to calculate "time-weighted-average (TWA)"-levels (TWA-TTC in urine: 53-640 mg/g creatinine). Nerve conduction velocity (NLG)-measurements of motor and/or sensory fibers of the ulnar and median nerve were performed to test peripheral nerve function. Seven employees were excluded. They had possible competitive risks of peripheral neuropathy, or were of less than 10 months exposed. For controls we examined 24 healthy persons of identical sex and age (matched pairs), but without known risks of a peripheral neuropathy. In comparing the nerve conduction velocities there were no significant differences between TRI-exposed and non-exposed persons. Correlation analyses and the individual assessment of the data concerning exposure/dose and effect revealed no signs of a "dose-effect-relationship".

Adolescent↗
PubMed1981

[Current cadmium load in the population. Comparison of cadmium concentrations in the kidney tissue of autopsies from 1969-1980].

Cadmium accumulates in the human kidney. Especially the cadmium-level in the cortex can be used as an indicator of the cadmium-burden. We analyzed tissue samples from 183 inhabitants of Bavaria to determine the amount and the changes in time of cadmium-burden in the general population. Autopsies and analyses were performed in 1969 (collective A: 25 men, 12 women, mean age of death 37.0 and 53.5 years, resp.), 1971/72 (collective B: 52 men, 54 women, mean age of death 65.0 and 66.8 years, resp.) and 1980 (collective C: 26 men, 13 women, mean age of death 37,5 and 52 years, resp.). Only the samples of the collective B were analyzed after separation into renal cortex and medulla. Anamnestic data were obtained from case history, smoking habits were not known in collective A and C. The comparisons of renal cadmium-concentrations during the last decade (1969-1980) did not substantiate an increase of cadmium-burden: Mean cadmium-concentrations are in 1969 (collective A) 8.4 and 7.9 micrograms cadmium/g wet weight (collective C) in 1980. The central 66%-ranges of both collectives matched in respect of age, sex, and cause of death. In all samples the values were below the discussed critical cadmium-concentration of 200 micrograms/g renal cortex wet weight. The highest concentration determined was 115 micrograms cadmium/g renal cortex (collective B). Our results further confirm the following: increase of renal cadmium-concentrations in older persons--higher cadmium-levels in renal cortex compared with medulla--and lower renal cadmium-concentrations in women in relation to men.

Adult↗
PubMed1981

[Investigations on neurotoxicity of chemical substances at the workplace. II. Determination of the motor and sensory nerve conduction velocity in persons occupationally exposed to pentachlorophenol (author's transl)].

We examined eighteen workers (three women, 15 men) in a pentachlorophenol (PCP) processing factory, with a mean activity of 12 years. PCP in blood and urine samples was analyzed by gas chromatography. To evaluate the peripheral nervous system the maximal motor as well as sensory nerve conduction velocities of the ulnar and/or median nerve were measured. The PCP-levels in plasma ranged between 0.02 and 1.5 ng/l, median 0.25 ng/l, and in urine between 13 and 1,224 micrograms/l, median 112 micrograms/l, or between 11 and 2,111 micrograms/g creatinine, median 111 micrograms/g creatinine. The median values of the neurophysiological parameters showed a mild degree of slowing in the PCP-collective. In the case of the sensory nerve conduction velocities, this decrease was significant. A dose-effect relationship between internal PCP-load and the different nerve conduction velocities could not be demonstrated. The individual evaluation of the toxicological and neurophysiological results gave hints that in some cases decreased nerve conduction velocity is caused by chronic exposure to PCP.

Adult↗