Back when I was an associate we had a refinery client with a benzene unit and the unit generated litigation along with the benzene. Interestingly, the union knew that benzene could cause fatal blood diseases back when the unit was built in the late 1950s. The union even sent down a benzene safety poster which was framed and hung in the control room. The operators were issued cartridge respirators for aromatics and had blood samples taken for testing on a regular basis. Far from being a worry, even after the Emergency Temporary Standard for benzene came out the unit was a favorite of those union members with the seniority to bid on to it. So much so that women with the requisite seniority would have hysterectomies so they could get around the so-called fertile female policy that prevented them from working on it.
Some early, and I might add poorly done, studies had suggested that benzene might cause birth defects. Accordingly many companies adopted policies that kept women who were otherwise qualified from working with materials or in operations feared to be teratogenic. Eventually the U.S. Supreme Court struck down such policies. See: International Union, United Automobile, Aerospace & Agricultural Implement Workers of America, UAW, et al v. Johnson Controls, Inc.
Nothing ever came of the claim that benzene was a teratogen and even in southeast Texas where injury and illness would otherwise not exist but for deep pocketed corporations we never had any benzene birth defect claims.
Now however there's a new study in Environmental Health Perspectives that compares EPA estimates of benzene exposures in Texas and the rates of spina bifida among people living in those areas during a recent five year period. It found for the area with the highest exposure a 2.3-fold increase in spina bifida; an association which was statistically significant.
Read all about it (free) in "Maternal Exposure to Ambient Levels of Benzene and Neural Tube Defects Among Offspring, Texas, 1999 - 2004"
Hat tip: The Houston Chronicle