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NIOSH's "Workplace Medical Mystery: Blurry Vision Affects Print Press Operator" - Solved

Monday, November 23, 2015

Article from the NIOSH Science Blog

Written By: Stephanie Stevens, MA - March 20th, 2015 7:25 am ET

It turns out Jim wasn’t the only one at work with vision problems (see mystery).

To his surprise, Jim discovered almost all of his co-workers who worked the line with him at the label production plant had experienced some sort of vision problems over the last year—including changes in vision, blurred vision or irritation. Once workers and supervisors compared notes, the company requested a Health Hazard Evaluation by the National Institute for Occupational Safety and Health (NIOSH). After taking workers’ job and medical histories, performing eye examinations, taking air samples, reviewing the literature on visual effects associated with chemicals commonly found in printing and other industrial processes, and analyzing samples of the ink used at the plant, the investigators arrived at a plausible association between the workers’ jobs and their symptoms.

Certain amines, chemical compounds derived from ammonia, have been shown to cause visual symptoms, such as blurred or hazy vision in both an industrial and laboratory settings. Amines are chemical compounds typically used as solvents, preservatives, drugs, or herbicides—or in the case of the label production plant, as part of the ink and ink additive.

The water-based ink used at the label production plant contains 1% DMAE, a type of amine. Additionally, workers add pH adjuster to the pails of ink every day that also contains a similar amine called DMIPA. The adjuster helps the ink maintain a proper pH balance, avoiding problems that can occur when pH is too low (the ink can become thick) or too high (the ink may dry too slowly). The NIOSH evaluation concluded that DMIPA, an amine that more readily evaporates at room temperature, was likely the culprit in these vision problems.

In response to the workers’ complaints, management at the plant began to dilute the pH adjuster with water. Additionally, staff were instructed to cover all ink pails to reduce the amount of chemicals that evaporated into the air.

Once these changes were made, workers no longer reported any difficulties with their vision.


Stephanie Stevens, MA is a Health Communication Specialist in the NIOSH Office of the Director. 

This is the first installment in the NIOSH Workplace Medical Mystery Series. This “mystery” is loosely based on Health Hazard Evaluation (HHE) reports conducted by NIOSH and other sources, and any recommendations made herein were for the specific facility evaluated and may not be universally applicable.  Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.  HHEs are publicly available at, but the names of individuals and facilities mentioned in the HHE reports and in this series have been changed to protect their identities.

For more information on the NIOSH HHE program, visit

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