NIOSH Links Vision Problems with Two Chemicals Used in Printing
January 24, 2003

For the first time, two chemicals associated with supposedly safer water-based inks used for printing production have been linked to job-related vision problems. Researchers from the National Institute for Occupational Safety and Health (NIOSH), working in conjunction with management and employees at a label printing plant, discovered employees' exposure to two chemicals, dimethylisopropanolamine (DMIPA) and dimethylaminoethanol (DMAE), both from a widely used category of chemicals called tertiary amines, caused blurred vision. Tertiary amines are widely found in solvents, chemical intermediates, catalysts, preservatives, drugs and herbicides.

The printing company requested help from NIOSH when several employees in the printing production area reported intermittent blurred vision. Although their vision typically improved within several hours of leaving work, the blurred vision caused a safety hazard while the employees were operating machinery on the job and while they were driving home.

Employees could not predict when the condition would occur, but it was beginning to happen more frequently, they reported. One employee was examined by an ophthalmologist, who discovered
"a film over his eyes."

NIOSH's investigation determined the condition was related to exposure to DMIPA, a component of an additive used to thin ink, and DMAE, a component of water-based inks. The number of employees reporting blurred vision, the number with film or opacities on the cornea and the severity of the opacity increased with corresponding exposure to the compounds.

Neither compound previously had been linked to vision disturbances in humans.

NIOSH measured exposure levels, assessed the plant ventilation system, administered eye examinations and questionnaires and used vigorous statistical analysis to assess the likelihood that a given exposure was associated with symptoms of visual change. Although it was impossible in the statistical analysis to distinguish the role of one compound from that of the other, NIOSH reports that DMIPA was the more likely suspected cause, although both compounds would be expected to produce the same effects.

As a result of the study the company began diluting the DMIPA used in the printing process. Visual symptoms immediately ceased.

Further recommendations were made to reduce exposures cost effectively by first controlling the specific sources of tertiary amines associated with the printing machines, and then repositioning the plant's outdoor air intakes and exhaust discharge locations.

According to NIOSH, based on the last data collected in the 1980s, 35,000 employees were estimated to have beeen exposed to DMAE and 20,000 to DMIPA. The agency estimates those numbers have increased dramatically because solvent-based inks increasingly have been replaced with water-based inks containing amines.

Susan Geier Fahmy, CSP

If you have any questions on this or any other safety issue, please call your local area representative or the Lovell Safety Office at 212.709.8600.