OSHA Hazard Information Bulletins
Health Hazard Information Alert Regarding Thixon 511-T
July 22, 1986
- JOHN MILES
- Directorate of Field Operations
- EDWARD BAIER
- Directorate of Technical Support
- RALPH YODAIKEN
- Office of Occupational Medicine
- Health Hazard Information Alert Regarding Thixon 511-T
On April 23, 1986, five rubber molding workers employed at Barr Rubber Corporation, Sandusky, Ohio were hospitalized for methemoglobinemia. Investigation by NIOSH found the cause to be from the contamination of an adhesive called Thixon 511-T with dinitrobenzene. The contaminant was traced to a curing agent which is supplied by Sandoz Chemical Corporation, Charlotte, North Carolina for the production Thixon 511-T. On May 28, Dayton Chenucak Division of the Whittaker Corporation, the manufacturers of Thixon 511-T, recalled Lots #6171 and #5231 because of dinitrobenzene contamination. Lot samples of the curing agent are not routinely retained by Sandoz for future chemical analysis. It is, therefore, possible that other lot numbers are also contaminated with dinitrobenzene.
Thixon 511-T is a solvent-borne adhesive which was being used by Barr Rubber to bond metal studs onto automotive rubber bumper strips.
Dinitrobenzene is (normally) used in the preparation of dyes and dye intermediates, as a polymerization inhibitor in the plastics industry, and as an explosive. The current OSHA standard for dinitrobenzene is 1 milligram per cubic meter of air (1 mg/m3) for an eight hour TWA with a "skin" notation. The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended a Threshold Limit Value exactly the same as the OSHA PEL.
Dinitrobenzene causes methemoglobinemia which prevents oxygen uptake in the blood and may, in rare cases, be fatal. The symptoms of acute exposure include cyanosis, a blue coloration of the lips and fingernails, and headache when the methemoglobin level exceeds 15 percent of the total hemoglobin. Breathlessness upon exertion, weakness, nausea and vomiting occur with levels above 40 percent. Levels greater than 70 percent can cause stupor, coma, and possibly death. Symptoms may be aggravated by alcohol and certain susceptible individuals are more likely to develop methemoglobinemia. Chronic exposure is associated with anemia, reduced vision and possibly liver damage.
Because methemoglobinemia can be asymptomatic, any worker exposed to Thixon 511-T should have a complete medical examination. Special attention should be given to:
- A present or past account of symptoms suggesting methemoglobinemia.
- A yellow discoloration to the skin from contact with dinitrobenzene and cyanosis (blue coloration of lips and fingernails).
- Blood studies including a complete blood count, liver enzymes, and a post-shift methemoglobin concentration.
Treatment is necessary for severe mehtemoglobinemia which requires hospitalization for supportive care and intravenous administration of methylene blue.