Safety Tidbit 3.18 - Initial Lead Exposure Assessment

Safety Tidbit 3.18 – Initial Lead Exposure Assessment

Reference: OSHA Lead Standard – 1910.1025

I was on a job site this week and doing some training for a new health consultant out of the Delaware OSHA On-site Consultation Program. OSHA cited the company for failure to assess if any worker may be exposed to lead at or above the action level and requested assistance to conduct lead monitoring. The company is an injection molding company that manufactures battery casings including the tops with the lead terminals. The compliance officer was concerned that during blow-off operations within the molding machine lead particles were made airborne in sufficient quantity to exceed the Action Level of 0.03 mg/m3.  The company had already requested Consultation services, so OSHA just wanted to see air monitoring performed. 

As I assessed the operation, I learned that the operator placed pre-formed lead terminals into the mold. The worker wears nitrile gloves to minimize skin contact. The operator loads molds into the injection machine where plastic is injected creating the battery top and encasing all but the tip of the terminal in plastic. As the tops are cut by the machine some small fragments are left over which are blown off using compressed air nozzles to prevent them from affecting the next mold.

Unfortunately, the machine had a failure the day I was there so I was unable to conduct air monitoring. However, my first thought wasn’t “Did you perform lead air monitoring during the incidental blow-off operations?” Which is an easy target for compliance officers unfamiliar with the injection process and the physical properties of lead. First, during blow-off operations, there is no abrasion of lead terminals, so there is no way for lead to become airborne. Second, the injection process operates at 390 degrees Fahrenheit. Too hot and the plastic burns and too cool the plastic doesn’t flow properly. So, the tolerances are tight and well controlled. Lastly, from the Safety Data Sheet, their pre-formed lead terminals melt between 486-600 degrees Fahrenheit. Therefore, the temperature in the machine never gets high enough even to melt the lead terminals (which would be counter to their process of manufacturing battery tops) let along make it airborne.

In accordance with 1910.1025(d)(3)(i)(A), the employer can assess their workplaces using any information, observations, or calculations which would indicate employee exposure to lead. I believe this would suffice. However, I will return to the facility and conduct full-shift air monitoring to assess lead exposure. Luckily, the PA/OSHA Consultation Program can do this for the employer for free.

Hope this was helpful and thanks for reading my Safety Tidbits! Comments and questions are always welcome. ~ Bryan

P.S. If you have an interesting safety or health question please let me know.