From the early 1980's on, millions of head of cattle were fed high protein dregs from rendering plants, and thousands of them developed mad cow disease.

In 1989, the American rendering industry initiated a voluntary program under which, for example, no sheep heads were to be accepted at rendering plants.

That's a product that comes out of rendering plants, where they process dead farm animals.

"Fire can be a major hazard in rendering plants," noted a 1976 safety manual published by the U.S. Department of Health, Education and Welfare.

Some also suggested that pollen from the engineered crops could render plants in neighbors' fields sterile without the farmers realizing it.

As a result, much of the screening for mad cow disease will move away from slaughterhouses to rendering plants and farms.

Currently it is used as a fuel in steam boilers in rendering plants and in the production of biodiesel.

Secaucus boasted numerous pig farms and rendering plants.

The city is also home to rendering plants, food processors, smelters and metal working companies.

About 70 percent of those tested since June, he said, are those that have died on farms or are received dead at rendering plants.