manual decanting
nto storage tanks using a hose and lance system. A similar approach was used to
prepare Hydrazine Hydrate for supply to customers; manual decanting into
containers of various sizes up to 1 tonne bulk containers. When HSE inspected the site and assessed both processes, HSE and the company agreed that there was a heavy reliance on both personal protective equipment (PPE) and Respiratory Protective equipment (RPE). The company also had a local exhaust
ventilation system on site which would only remove escaping vapors when near the
source of exposure, therefore offering a limited level of protection. This was important
given that the company had discovered that airborne exposure concentrations during
manual transfers were in excess of the assigned regulatory exposure limit for
Hydrazine, although no employee was known to be exposed to hydrazine vapor
above the regulatory limits.
Substitution – using a less harmful chemical with similar properties was not a viable
option for the company as there was no other practicable alternative oxygen
scavenger for use in high pressure boilers. Overall, the potential for worker exposure coupled with a heavy reliance on PPE raised concerns for both HSE and the company.
At the heart of the shared dilemma was the need to minimize the potential for worker
exposure to a vital, but harmful chemical.
C. Case Study: Jennifer*
Jennifer is a nulliparous, 30-year-old healthy woman who presents to your office for her annual well-woman exam. She was recently married and is contemplating pregnancy within the next year. She has no complaints except for occasional headaches, which occur sometimes at work but never on weekends.
Jennifer has worked as a lab technician at a local polymer manufacturer for the past 6 years. She is concerned about possible chemical exposure at work. For protective equipment she uses eye protection, an apron, and latex gloves. There is no ventilation hood in the lab. The primary chemical she works with is N-methylpyrrolidone (NMP), a chemical used to dissolve a wide range of other chemicals. She is exposed to NMP on a weekly, and often daily, basis.
Jennifer’s exam is normal. The pregnancy test that you order is negative. You pull up the material safety data sheet (MSDS) for NMP online, which you review with Jennifer. The MSDS mentions no adverse reproductive effects, and Jennifer is relieved. However, knowing that MSDS entries are often incomplete and inaccurate with regard to information on the reproductive effects of the chemical, you investigate NMP in more detail on the Internet. You learn that in 2001, NMP was listed as a known reproductive toxicant in the state of California on the basis of animal studies.6 You search the developmental and reproductive toxicology database at the TOXNET Web site and find several entries, including a case of a pregnancy loss in a lab technician exposed to NMP.
On the basis of the information from the Internet and the toxicology database, you refer Jennifer to an occupational health specialist. You receive a note from the specialist after Jennifer’s consultation. She has recommended the use of additional safety precautions at Jennifer’s workplace, including a ventilator hood, a well-fitted respirator, neoprene rather than latex gloves (the former are more resistant), and continued use of the apron and eye protection.
