NEUROPSYCHOLOGICAL SEQUELAE OF WELDING

Rosemarie M. Bowler, San Francisco State University, 8371 Kent Drive, El Cerrito, CA, 94530, rbowl@sfsu.edu; Andrew Booty, Pomona College; Christopher Hartney, San Francisco State University; and Donna Mergler, Université du Québec à Montréal

ABSTRACT

The objective of this study was to compare the neuropsychological function, emotional status, visual function, and illness prevalence of 86 former and current chemical industry welders exposed to welding fumes for an average of 23.2 years with that of a group of 77 unexposed, non-welder controls. Health and occupational history questionnaires were administered, as were neuropsychological tests from the WHO NCTB, Luria Motor, WAIS-III, and WMS-III. Emotional status tests included the BSI, POMS, BAI, and BDI, and vision tests included the Lanthony d-15 color vision, the Vistech Contrast Sensitivity, and Schirmer strips. The welder group performed worse than the controls in the domains of motor efficiency, cognitive flexibility, visuomotor tracking speed, verbal learning, and working memory; no differences were found in the domains of verbal skills, verbal retention, auditory span, or on the Rey 15-item malingering test. Additionally, welders demonstrated dysfunction in emotional status, illness prevalence, color vision, and psychiatric symptoms.

INTRODUCTION

Welding has been shown to be a hazardous vocation due to frequently unprotected exposure to heavy metal fumes, including high levels of Manganese, Chromium, and Iron Oxide, all of which can be contained both in welding rod coatings and in the material being welded (Chandra, Shukla, Srivastava, Singh, and Gupta, 1981). Manganese exposure has been associated with cognitive dysfunction and emotional disturbance (Bowler, Mergler, Sassine, Larribe, and Hudnell, 1999). Welders are also often exposed to high concentrations of Carbon Monoxide and Nitrogen Dioxide, and exposure to welding fumes and airborne particles has been associated with both central and peripheral nervous system damage, as well as respiratory problems, metal fume fever, kidney problems, skin irritation and angioedema, and cancer (Sjogren, 1993).

METHODS

The sample consisted of 86 welders from different welding shops and industries in a rural area of Eastern Texas who were compared with 77 unexposed, non-welder controls from the same geographic region (Table 1).

Table 1: Demographics of Sample
	Welders (n=86)	Controls (n=77)	Sig.
Ethnicity:			.002
African American	14 (16.3%)	31 (40.2%)
White	72 (83.7%)	48 (62.3%)
Age (years):
African American	46.3	46.3	.997
White	54.3	54.1	.926
Years of Education:
African American	12.4	13.3	.140
White	10.9	12.9	.001

All potential control participants were screened and excluded a priori if they had any history of prior chemical exposure, sensory (hearing, visual acuity) problems, or serious diagnosed illness that would affect performance on the tests, e.g., head trauma, Parkinson’s Disease, alcoholism, or psychosis. There were no significant differences for smoking, with 19% of the welders vs. 23% of the controls currently smoking. Neuropsychological tests were selected from the WHO NCTB, Luria Motor, WAIS-III, and WMS-III, and also included the BSI, POMS, BAI, and BDI. Vision tests included the Lanthony d-15 color vision, the Vistech Contrast Sensitivity, and Schirmer strips.

The tests were administered by psychologists and advanced clinical psychology graduate students. Informed consent was obtained from all participants, and testers were blinded as to the exposure status of the participant being tested. The order of neuropsychological test administration was the same for all participants. All test data were scored according to their respective manuals and all data were rechecked for accuracy and reliability.

Significant demographic differences were found between welders and controls for years of education (for Whites only) and ethnicity; these differences were accounted for with appropriate adjustments in all statistical analyses. Because of neuropsychological score differences between African Americans and Whites, each group’s scores were analyzed separately. Univariate analyses of variance were performed on all neuropsychological, vision, and emotional status scores. Age, ethnicity, and education level were entered as covariates for the neuropsychological and emotional test analyses, unless the test score was already corrected for these demographic variables. Logistic regressions, adjusting for the effects of age, and when appropriate, smoking, were used to compare illness prevalence between groups.

RESULTS AND DISCUSSION

The welders worked an average of 23.2 years in welding and reported being exposed to welding fumes an average of 81% of that time. In the summertime, welding shop doors were open for ventilation an average of 70% of the time and windows an average of 58% of the time, but in winter these averages dropped to 24% and 14%, respectively. Over 60% of the welders reported a visible haze and/or smoke present over 75% of the time on average in their work place. Only 9.2% of the welders reported having access to air-supplied respirators and 10.2% cartridge respirators. After adjusting scores for education and age, when appropriate, scores on tests of verbal skills, verbal retention, auditory span, as well as scores on the Rey 15-item malingering test were not significantly different between welders and controls for African Americans or for Whites. However, in comparison to controls, the welders had significantly (p < .05) lower scores than the controls on all of the tests of motor efficiency, cognitive flexibility, visuomotor tracking speed, verbal learning, and working memory listed in Table 2. Means of these test scores are listed by domain, exposure group (Welder and Control), and Ethnicity (African American [AA] and White).

Table 2: Means of Neuropsychological Test Scores (Adjusted for Age and Education, as Appropriate) Between Welders and Controls
Domain:	Welders (n=86)		Controls (n=77)		Sig.
	AA	White	AA	White
Motor Efficiency
Luria Motor right hand scaled score	0.5	0.2	0.3	0.1	.032†
Dynamometer dominant hand T-score	34.7	30.4	39.4	35.1	.014†
Fingertapping nondominant hand T-score	36.8	39.8	46.8	49.9	.000
Grooved Pegboard dominant hand T-score	38.6	40.9	43.6	45.9	.001
Grooved Pegboard nondominant hand T-score	37.8	41.3	44.0	47.4	.000
Cognitive Flexibility
COWAT percentile	33.9	38.2	46.3	50.6	.012
Stroop color-word T-score	31.2	40.1	34.9	43.8	.025†
Trail Making Test B T-score	34.6	42.4	37.9	45.8	.027†
Visuomotor Tracking Speed
WAIS-III Digit Symbol-Coding age scaled score	5.8	6.7	7.7	8.6	.000†
WAIS-III Symbol Search age scaled score	6.9	8.4	8.4	9.9	.000†
WAIS-III Processing Speed Index	80.5	86.6	89.6	95.7	.000†
Trail Making Test A T-score	33.7	46.1	41.4	47.6	.050†
Verbal Learning
WMS-III Auditory Immediate Index score	83.1	91.8	91.0	99.7	.001†
Working Memory
WAIS-III Working Memory Index score	82.2	91.5	87.0	96.3	.035†

† significant at p<.05 based on ethnicity

The welders also demonstrated deficits in color vision. Lanthony d-15 Color Confusion Index scores were significantly higher (p<.05) for welders compared to controls for both the right eye (welders=74.49, controls=57.19) and the left eye (welders=68.20, controls=55.02). Welders also had significantly more left and right crossings (p < .05).

The welders scored significantly worse than the controls on all BSI and POMS scales. They reported more psychiatric symptoms and psychotic-like feelings, as well as greater levels of anger and anxiety. 72% of the welders were clinically ‘abnormal’ on the BSI, with no significant differences between African Americans and Whites within either exposure group.

Results of logistic regressions of “doctor diagnosed” illnesses showed that, compared to controls, the welders reported a significantly greater prevalence (p<.05) of insomnia, acute bronchitis, cardiac problems, skin rashes, kidney infections, blood in urine, back or spine problems, Parkinson’s Disease, nervous disorder, depression, and anxiety.

Welders also reported an excess of neurological symptoms, including tremors, weakness and cramping in legs, sexual disturbance, and sleep disturbance.

DISCUSSION

The group of welders under study were exposed to welding fumes during the majority of their employment, particularly during the wintertime and often without respiratory protection. Consistent with the literature, the welders had poorer scores compared to controls on neuropsychological and emotional status tests, as well as reduced color vision, greater levels of dyschromatopsia, and increased prevalence of neurological symptoms and illnesses. These results suggest that welding fumes act on specific areas of the central and peripheral nervous system and other organ systems. A limitation in this study is that these welders were also exposed to a variety of organic solvents, as is often the case for individuals welding in a chemical industry setting. However, this group’s primary chemical exposure was to welding fumes.

REFERENCES

Bowler RM, Mergler D, Sassine M-P, Larribe F, & Hudnell K. (1999). Neuropsychiatric effects of manganese on mood. NeuroToxicology, in press.

Chandra SV, Shukla GS, Srivastava RS, Singh H, & Gupta VP. (1981). An exploratory study of manganese exposure to welders. Clinical Toxicology. 18 (4): 407-416.

Iregren, A. (1999). Manganese neurotoxicity in industrial exposures: proof of effects, critical exposure level, and sensitive tests. NeuroToxicology. 20(2-3): 315-324.

Mergler D, Huel G, Bowler R, Iregren A, Belanger S, Baldwin M, Tardif R, Smarigassi A, Martin L. (1994). Nervous system dysfunction among workers with long-term exposure to manganese. Environmental Research. 64: 151-180.

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