Effects of occupational exposure to arsenic on the nervous system: Clinical and neurophysiological studies

Abstract

Objectives: A number of metals, especially heavy metals, exhibit neurotoxic properties. Neurological and neurophysiological studies indicate that the functions of the central (CNS) and peripheral nervous system (PNS) may be impaired under conditions of exposure to arsenic (As). The aim of the present study was to assess the effects of inorganic arsenic on the central and peripheral nervous system. Materials and Methods: The study covered a group of 21 male workers (mean age: 41.9 yr; SD: 7.6; range: 31-55 yr) employed in a copper smelting factory. Their employment duration ranged from 5 to 33 years (mean: 18.1 yr; SD: 7.8). Arsenic concentrations in workplace air amounted to 0.01003 mg/m 3 on average (SD: 0.00866). Urine arsenic concentrations ranged from 3.48 to 23.63 μg/l (mean: 11.91 μg/l; SD: 9.5). The control group consisted of 16 males non-occupationally exposed to As, matched for gender, age and work shift pattern. The evaluation of neurological effects was based on the findings of neurological examination, electroencephalography (EEG), visual evoked potentials (VEPs) and electroneurography (ENeG). Results: Clinical symptoms, such as sleeplessness or sleepiness, irritability, headache, painful spasms in extremity muscles, extremity paresthesia and pain, and muscular fatigue prevailed among functional disorders of the nervous system in workers chronically exposed to As. Neurological examination did not reveal any organic lesions in the CNS or PNS. In EEG records classified as abnormal, generalized changes were most common. VEP examinations revealed abnormalities in evoked response latency. Stimulation of the motor fibers of the peroneal and medial nerves resulted in a decreased amplitude of the motor potential. Stimulation of the sensory fibers of medial nerves brought about a decreased amplitude of the sensory potential and a lower conduction velocity of the sural nerves. Conclusion: The findings of the study indicate that exposure to As concentrations within the threshold limit values (TLV) can induce subclinical effects on the nervous system, especially subclinical neuropathy.

Risk agents related to work and amyotrophic lateral sclerosis: An occupational medicine focus

“…Some evidence in experimental models concerning neurotoxicity of other metals such as zinc and copper [88,89] is also present in scientific literature, but there is no strong evidence concerning relationship with ALS. Little evidence about occupational exposure to aluminum and the onset of neurological disorders compatible with degenerative motor neuron disease is present in scientific literature: Sińczuk-Walczak [90] has examined aluminium effects on the functions of the nervous system in people occupationally exposed to dust and fumes containing this metal. The author has mostly found neuro-behavioral and bioelectric cerebral disorders, and less frequently neurological symptoms correlated with a motor neuron disease.…”

Plasma and Urinary Aluminum Concentrations in Severely Anemic Geophagous Pregnant Women in the Bas Maroni Region of French Guiana: A Case-Control Study

“…Neurocognitive problems and subtle electroencephalographic changes have been observed in aluminum workers with urinary aluminum concentrations of the order of 41 μg/L, a level reached in one-third of our patients. 32,33 The prospect of fetal damage is even more worrying, because aluminum crosses the placenta and may become fixed in the fetal brain, disturbing its development. 12,34 Reports of psychomotor abnormalities in young rats born to dams fed clay during the gestation period seem to confirm this hypothesis.…”

Neurological and neurophysiological examinations of workers exposed to arsenic levels exceeding hygiene standards

“…The analysis of occupational exposure of workers in the copper smelter factory, the nature and localization of clinical and neurophysiological lesions, the characteristic feature of the optic neuron dysfunction and the correlations between biological monitoring parameters and inorganic arsenic levels in the workplace air strongly support the hypothesis of the predominating neurotoxic effect of inorganic arsenic. Compared to the studies reported earlier [22,23], results presented in this paper were obtained with the use of ICP-MS and apply to a different population of workers exposed to inorganic arsenic. Monitoring of the effects of occupational exposure to arsenic and its inorganic compounds on the nervous system, as well as the outcomes of determining urine concentrations of As species should contribute to the prevention of As exposure and provide the direction for further studies.…”