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Administrative data

Endpoint:
health surveillance data
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
not reported, published 2003
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well-documented study which meets basic scientific principles

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2003

Materials and methods

Study type:
medical monitoring
Remarks:
ocular changes
Endpoint addressed:
eye irritation
Test guideline
Qualifier:
no guideline required
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
2-dimethylaminoethanol
EC Number:
203-542-8
EC Name:
2-dimethylaminoethanol
Cas Number:
108-01-0
Molecular formula:
C4H11NO
IUPAC Name:
2-(dimethylamino)ethanol
Details on test material:
- Name of test material (as cited in study report): dimethylaminoethanol (DMAE)
- Substance type: organic solvent
- Physical state: liquid
- Analytical purity: Air born concentrations are summarized in the Table 1 in "Any other information on materials and methods"

Method

Type of population:
general
Ethical approval:
confirmed, but no further information available
Details on study design:
Questionnaires, eye examinations (visual acuity, contrast sensitivity at 2.5 % and 1.25 % contrast, slit lamp biomicroscopy, and pachymetry), and industrial hygiene monitoring for DMIPA (another amine) and DMAE were performed over a two week period.

Results and discussion

Results:
One hundred per cent of line and prime workers present at the time of the study filled out the baseline questionnaire, 24 from the prime division and 36 from the line division of the plant. Eighty nine per cent of line workers reported having experienced blurry vision while at work in the past 12 months, compared to 12.5% of prime workers (p < 0.01).

Any other information on results incl. tables

Findings were similar for halo and blue-grey vision, with 72% of line workers reporting halo vision compared to 8% of prime workers (p< 0.01), and 14% of line workers reporting blue-grey vision compared to 0% of prime workers (p = 0.08). None of the workers reported medical conditions that would affect their vision. Forty seven per cent of those reporting blurry, halo, or blue-grey vision experienced eye irritation along with the visual changes, 44% reported difficulty performing their job as a result of the visual changes, and 39% reported difficulty driving home.

There was a positive association between reported visual symptoms and PBZ concentrations of total amines. Exposures to higher levels of total amines were associated with increased risk of reporting blurry vision (OR (odds ratio from regression analyses) 1.78, 95% CI (confidence interval) 1.41 to 2.26), halo vision (OR 1.38, 95% CI 1.20 to 1.58), and blue-grey vision (OR 1.77, 95% CI 1.31 to 2.39) at the end of a shift. All OR reported in this paper reflect a per unit increase of 1mg/m3 in amine concentration. Symptom reporting increased with exposure to increasing concentrations of amines (Table 2). Results were similar when evaluating the relation between symptom reporting and exposure to the individual amines (DMIPA and DMAE).

Table 2  Prevalence of reported visual symptoms by total amine concentrations

Full shift total amine concentrations (mg/m3)*

n

Blurry vision

Halo vision

Blue-grey vision

0.84-7.30

26

3 (12%)

1 (4%)

0 (0%)

7.31-13.80

57

26 (46%)

11 (19%)

7 (12%)

13.81-20.33

13

12 (92%)

7 (54%)

8 (62%)

*Range was divided into three groups of equal width.

The risk of developing corneal opacity over a shift rose with increasing exposure to total amines. The prevalence of corneal opacity also increased with exposure to increasing concentrations of total amines (data not shown).

The prevalence of increased corneal thickness in either eye over a shift increased with higher levels of exposure to total amines, as did both the mean and median changes in thickness (data not shown). There was a positive association between increases in across-shift corneal thickness and concentrations of total amines; however, it was not statistically significant.

There was a statistically significant relation between total amine concentration and increased risk of reductions in bilateral visual acuity and contrast sensitivity at 2.5% contrast over a shift. Similar results were found for two amines separately, but were not statistically significant for DMAE. There was not a significant association between reduced contrast sensitivity at 1.25% contrast and concentrations of total amines, DMAE, or DMIPA.

Applicant's summary and conclusion

Conclusions:
1. Exposure to DMAE can cause corneal opacity, with resultant decrements in visual acuity and contrast sensitivity.
2. These effects, while reversible, pose an immediate safety hazard.
Executive summary:

The study was performed to determine if exposure to two tertiary amines (one of them is dimethylaminoethanol (DMAE)) in a label printing plant was associated with visual disturbances and/or ocular changes.

Eighty nine per cent of line workers reported having experienced blurry vision while at work in the past 12 months, compared to 12.5% of prime workers. A total of 108 full shift personal breathing zone (PBZ) air samples for the amines were collected. The mean TWA concentration of DMAE was higher in the prime division than the line division (Table 1 in "Materials and methods"). Higher levels of total amines were associated with increased risk of reporting blurry vision, halo vision, and blue-grey vision (Table 2 in "Remarks on results"). The risk of corneal opacity rose with increasing exposure to total amines. The prevalence of corneal opacity also increased with increasing concentration of total amines. Median corneal thickness increased with increasing grades of corneal opacity. There was a statistically significant relation between total amine concentration and increased risk of reduced bilateral visual acuity and 2.5% contrast sensitivity.

" The re-entry of exhausted air is a potential problem, and the ventilation in the line division is not adequate under current work practices. Although increasing the general ventilation may provide some reduction in exposure, a more cost effective solution would be to improve the local exhaust ventilation controlling the sources of tertiary amines associated with the printing machines, and then to also reposition the outdoor air intakes and exhaust discharge locations."

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