Sequelae of fume exposure in confined space welding: A neurological and neuropsychological case series
Introduction
Manganese intoxication was first described in 1837 by John Couper (UK) in pyrolusite ore grinding workers who were observed with signs and symptoms which presently would prompt diagnosis of manganism. Reports of health effects from manganese (Mn) in welding fume exposures have been relatively recent (Racette et al., 2005). Table 1 summarizes our review of the literature of health effects of Mn exposure in the domains of tremor, motor, neurocognitive, memory, vision, sleep, sexual function, and mood for the period of 1955–2006. Apart from the study by Mergler et al. (1999) on environmental Mn exposure, these occupational Mn exposure studies, other than the relatively few in welders (highlighted in bold), deal with exposures from mining and smelter activities, ferroalloy and dry battery production, and pesticide (Maneb) manipulation.
Manganese has been shown to cause a parkinsonian syndrome sometimes referred to as manganism which is often misdiagnosed as Parkinson's disease (PD). Similarities between symptoms of PD and manganism include tremor, masked facies, generalized bradykinesia (abnormal slowed movement associated with movement initiation difficulties) and cogwheel rigidity (Feldman, 1999). Differences may include more frequent dystonia (slow, involuntary, arrhythmic muscle contractions) in manganism and a tendency to fall backward in PD and falling forward in manganism. Magnetic resonance imaging (MRI) can be used to reveal Mn2+ deposition in the brain, exhibiting a T1-weighted signal hyperintensity, especially in the globus pallidus and striatum, in both animals (Shinotoh et al., 1995) and humans exposed to manganese (Nelson et al., 1993, Kim et al., 1994, Kim et al., 1998, Kim et al., 1999a, Kim et al., 1999b, Lucchini et al., 2000, Dietz et al., 2001, Gasparotti et al., 2002). PD is associated with lesions in the substantia nigra pars compacta and does not produce similar MRI abnormality as manganism (Kim, 2006). Other differentiating features between manganism and PD are younger age of onset and little or no response to l-dopa among the manganism cases (Lu et al., 1994, Feldman, 1999, Koller et al., 2004). Case reports of neurological findings in career welders exposed to Mn have revealed dystonia bilaterally in the shoulders and distal four limbs, as well as other parkinsonian features (Sato et al., 2000, Koller et al., 2004, Bowler et al., 2006b).
In patients who have had manganese intoxication, the MRI can have diagnostic value provided the scans are done within less than 6 months of cessation of exposure (Lucchini et al., 2000), whereas blood, serum or urine Mn concentrations are not very useful for neurotoxic risk assessment. Nevertheless, increased manganese levels in blood were often found in groups of workers exposed to Mn dust and fumes (Roels et al., 1987, Roels et al., 1992, Wang et al., 1989, Lucchini et al., 1995, Lucchini et al., 1997, Lucchini et al., 1999, Sjögren et al., 1996, Deschamps et al., 2001, Chia et al., 1993, Mergler et al., 1994, Yim et al., 1998, Moon et al., 1999). Herrero et al. (2006) described findings of markedly elevated urinary manganese levels after administration of a chelating agent (CaEDTA) to seven patients, one of whom was a welder affected by Mn-induced parkinsonism, but urinary Mn is not frequently used as an exclusive biomarker for Mn exposure because the kidney is not a major excretion route.
Neuropsychological testing procedures developed over the past two decades have been shown to be successful tools to differentiate Mn-exposed welders from controls (Sjögren et al., 1996, Bowler et al., 2003a, Bowler et al., 2006a, Bowler et al., 2006b). Recently, we conducted a study in a group of 49 welders working on the new San Francisco Bay Bridge using neurological and neuropsychological methods (Bowler et al., 2006c). A neurological risk assessment of this welder group estimated an excess lifetime risk for disabling or fatal health outcome (Park et al., 2006). The present investigation builds on this initial health study and its objectives are (1) to select clinical cases based on neurological and neuropsychological signs and symptoms; (2) to determine if in this group of cases dose–effect relationships exist between neurological, neuropsychological, and neurophysiological functions and Mn concentration in whole blood or the cumulative exposure index (CEI); and (3) to improve knowledge on a neurological/neuropsychological portrait of manganism.
Section snippets
Participants and exclusion criteria
The San Francisco/Oakland Bay Bridge was damaged during the 1989 earthquake and reconstruction of a vulnerable portion of the bridge began in 2003. During the first 1.5 years of welding on the support piers of the new bridge, a group of welders reported concerns over welding fume exposures. Most bridge welders reported that they wore no personal protective equipment and that ventilation was minimal. This is supported by an audit by a California State auditor who reported that CAL-OSHA was found
Results
Table 2 shows characteristics of demographics, work history, reported use of respirators, and exposure. Two welders reported smoking in the past and only one (9.1%) is currently smoking. Air manganese and CEI averaged 0.22 mg/m3 and 2.73 mg/m3 × month, respectively. Eight (73%) of the selected welder cases had elevations in their MnB levels (>10 μg/L), while all cases showed blood lead levels <5 μg/dL and none was iron deficient. Comparison between the group of 11 selected clinical cases and the
Discussion
This report deals with 11 clinical welder cases selected out of a group of 43 welders with documented exposure to manganese from confined space welding on the San Francisco/Oakland Bay Bridge. The main neurological feature for their selection was the presence of signs and symptoms as revealed by the neurologist with the UDPRS-examination, a validated tool for detection/evaluation of parkinsonism. The specific symptoms picked up by the UPDRS-exam were: tremor (n = 11), bradykinesia (n = 9), postural
Disclaimer of Conflict of Interest
The first author (RMB) was paid by the participants’ employer to conduct neuropsychological evaluations of the employees as part of State and Federal Workers’ Compensation administrative law proceedings. The welders workers compensation attorneys made a contribution for the medical assistants and their incidental supplies during the 2 days of the study in January 2005. These welder's participants, in turn, agreed to participate for free in the study. None of the authors has been retained by any
Acknowledgements
Dr. William Koller, deceased October 3, 2005, who first suggested our selecting a smaller ‘clear’ clinical group, did all of the neurological examination and gave input on the design of the study. Dr. Edward Baker also is given appreciation for his encouragement and support during the initial scientific planning phase of this research. Dr. Donald Smith and Dr. Roberto Gwiazda generously performed the blood analyses—they are thanked and acknowledged.
Dr. Sabine Gysens, Dr. Stephen Rauch, and Dr.
References (94)
- et al.
Human neurobehavioral research methods: impact of subject variables
Environ Res
(1997) - et al.
Quantifying postural tremor in workers exposed to low levels of manganese
J Neurosci Methods
(2004) - et al.
Manganese exposure: neuropsychological and neurological symptoms and effects in welders
Neurotoxicology
(2006) - et al.
Parkinsonism due to manganism in a welder: neurological and neuropsychological sequelae
Neurotoxicology
(2006) - et al.
Neuropsychological sequelae of exposure to welding fumes in a group of occupationally exposed men
Int J Hyg Environ Health
(2003) - et al.
Neuropsychological effects of ethylene dichloride exposure
Neurotoxicology
(2003) - et al.
Manganese poisoning: clinical and biochemical observations
Environ Res
(1974) - et al.
Results of magnetic resonance imaging in long term manganese dioxide-exposed workers
Environ Res
(2001) Psychological test performance in foundry workers exposed to low levels of manganese
Neurotoxicol Teratol
(1990)Neuroimaging in manganism
Neurotoxicology
(2006)
Motor function. Olfactory threshold, and hematological indices in manganese-exposed ferroalloy workers
Environ Res
Nervous system dysfunction among workers with long-term exposure to manganese
Environ Res
The nervous system effects of occupational exposure on workers in a South African manganese smelter
Neurotoxicology
Issues in neurological risk assessment for occupational exposures: the Bay Bridge welders
Neurotoxicology
Pesticide exposure and neuropsychological impairment in migrant farm workers
Arch Clin Neuropsychol
A comprehensive study on neurobehavior, neurotransmitters and lymphocyte subsets alteration of Chinese manganese welding workers
Life Sci
Neuropsychiatric manifestation of chronic manganese poisoning
J Neurol Neurosurg Psychiatry
Evaluation of impairment/disability secondary to respiratory disorders
Am Rev Respir Dis
Adult environmental neurobehavioral test battery
Role of manganese in dystonia
Adv Neurol
Neuropsychological function in manganese alloy plant workers
Int Arch Occup Environ Health
Neuropsychological dysfunction, mood disturbance, and emotional status of munitions workers
Appl Neuropsychol
Neuropsychiatric effects of manganese on mood
Neurotoxicology
An exploratory study of manganese exposure to welders
Clin Toxicol
Neurobehavioral functions among workers exposed to manganese ore
Scand J Work Environ Health
Chronic manganese intoxication
Arch Neurol
On the effects of black oxide of manganese when inhaled into the lungs
Br Ann Med Pharmacol
Results from eleven years of neurological health surveillance at a manganese oxide and salt producing plant
Neurotoxicology
CATSYS 7. 0 user's manual
D-KEFS: Delis Kaplan executive function system
Standardization of a neuromotor test battery: the CATSYS system
Neurotoxicology
SCL-90-R administration, scoring and procedures manual–II for the revised version and other instruments of the psychopathology rating scale series
Neurological effects in workers exposed to manganese
J Occup Environ Med
Occupational Mn parkinsonism: magnetic resonance imaging and clinical patterns following CaNa2EDTA chelation
Neurotoxicology
The smell identification test: administration manual
Prevalence and association of welding related systemic and respiratory symptoms in welders
Occup Environ Med
The unified Parkinson's disease rating scale
Manganese
Occupational and Environmental NeuroToxicology
Chronic exposure to the fungicide maneb may produce symptoms and signs of CNS manganese intoxication
Neurology
Use of brain MRI in manganese exposure
Clinical findings from a new contrast sensitivity test chart
Standardized training tools for the UPDRS activities of daily living scale: newly available teaching program
Mov Disord
Stroop Color Word Test: a manual for clinical and experimental uses
Welding health and safety: a field guide for OEHS professionals
Follow-up of patients affected by manganese-induced parkinsonism treated with CaNa2EDTA
Neurotoxicology
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Deceased October 3, 2005.