Our coverage of BP this week examined the company's role in the industry, comparing it with other oil giants in terms of production, spills and worker-safety violations. One thing we had to leave out was worker fatalities.

That's because of a quirk in how OSHA, the federal agency charged with protecting workplace safety, keeps track of the information: OSHA lists deaths according to the company that employed the dead workers, not by the company responsible for their deaths.

Take, for example, the 2005 explosion at a BP refinery in Texas City that killed 15 workers. A search for database records of the accident revealed that OSHA cited BP for hundreds of violations and millions of dollars in fines. However, if you search through BP's OSHA records, you will find no death in that blast attributed to BP.

An OSHA spokeswoman said the agency tracks fatalities by primary employer because it is that employer's job to train the worker and keep the workplace safe.

According to the agency's records, the 15 workers who died in Texas City were employed by one of four companies that did work at the refinery: JE Merit Constructors, Inc., Fluor EPCM Services, Inc., TRS Staffing Solutions, Inc. or General Electric International, Inc. The workers' primary employers were not cited or fined for the accident, and there is no field to link the death listings to the responsible party, BP.

When we couldn't find any deaths in the Texas City explosion records, we went back to OSHA for help. After two weeks, an OSHA spokeswoman showed us records under the subcontractors' names. Although those online subcontractor records mention BP in accident descriptions, no such mentions exist in the searchable database to link to BP's records.

That means it's virtually impossible to compare companies when it comes to worker deaths, because you would have to know the names of every contractor and subcontractor at the facility on the day of each accident. OSHA offered a tedious solution: Find records coded as "fatality/catastrophe" and search close to the accident date by location to find related contractor deaths. That didn't work because, for some reason, not all fatal accidents are coded as accidents. For instance, the Texas City Refinery explosion was coded as a "referral" on the record created the date it occurred.

We didn't find a solution from other agencies. The Texas Department of Insurance, which handles workers' compensation in Texas, doesn't track deaths by responsible party either. Fatalities are reported to the department by the employer, "not necessarily the location where a death occurred," a spokesman told us.

Tracking worker deaths in the future may be easier. OSHA says it's replacing its decades-old tracking system with one that will link deaths to owners. It plans to have the new system up next year.