Of all the food safety concerns raised by the discovery of Mad Cow disease two weeks ago, perhaps none is more focused than the questions about ground beef, the main ingredient for hamburger, a staple of many an American's diet.

Hamburger meat from the infected cow actually made its way into the distribution system before the Mad Cow diagnosis was confirmed, prompting a hamburger meat recall in eight Western states and the US territory of Guam.

As opposed to other cuts of meat which are generally identified as to their source of origin on the cow, most non-kosher hamburger meat sold in this country is combined from several animals, and different parts of those animals as well, some of which are much safer than others, with regard to Mad Cow disease. Scientists believe that the Mad Cow infection is harbored in the cow's nervous system, which has led to requirements on American meat plants to treat the brains and spinal cords of all slaughtered animals as unfit for human consumption. But there is still a problem, because cuts of meat taken from near a cow's spinal column might still be contaminated with nearby nerve tissue.

In terms of kosher cuts of meat, that would include standing rib roast, chuck or round steaks, as well as beef stock made from neck bones.

The risk is greater for those same cuts of meat from non-kosher slaughterhouses, because many of them use advanced machinery to take every piece of meat off the bone, right up to the spinal column, increasing the likelihood of having Mad Cow contaminated nerve tissue mixed in.

Also, once infected, it doesn't matter how long the meat is cooked, because, unlike other food contaminations, such as E coli the prions that cause Mad Cow disease are not neutralized by cooking temperatures. Irradiation, another widely used method to decontaminate meat from other sources of infection, does not help make mad cow contaminated meat any safer.

Buying kosher meat does seem to be safer with regard to the Mad Cow threat. For starters, no downer cow too sick to walk on its own power would ever be slaughtered.

According to Rabbi Shalom Fishbane, Kashrus (kosher) Administrator for the Chicago Rabbinical Council (cRc), a "downer" cow is referred to in Jewish legal literature as a mesukenes, and would not be acceptable, according to current standards, as suitable for slaughtering.

But until the newly announced US Department of Agriculture (USDA) regulations forbidding it went into effect last week, 190,000 downer cows a year were slaughtered for their meat and allowed to enter the distribution system, with the only proviso being the removal of their brain and spinal column tissue. Kosher slaughtered cows, in contrast, are generally too young to exhibit Mad Cow symptoms, even if they have been exposed to the disease. Kosher slaughterhouses typically use cows between 18-24 months old, whereas the symptoms of Mad Cow disease do not generally appear until an infected cow is at least four or five years old.

Another potential Mad Cow risk factor not present in kosher slaughtered meat is the stunning of cows with a blow to the head, a practice now banned by the new USDA regulations. The fatal stunning blow to the animal's skull often winds splattering potentially infected brain matter throughout the animal's body, contaminating muscles and organs that would otherwise not pose a danger of spreading the Mad Cow infection.

Rabbi Fishbane notes the irony in the fact that in European countries where the legality of kosher slaughtered meat has been challenged, the complaint against it has been that it is less humane than stunning the cow. Now, it turns out that stunning cattle in non-kosher slaughterhouses is a major health hazard in its own right.

However, Rabbi Fishbane observes that common practice in kosher slaughterhouses further reduces the likelihood of mad cow infections.

He says that feedlot cattle, those most susceptible to contracting Mad Cow from contaminated feed, are generally less healthy than pasture-raised, grass-fed beef, which are never exposed to the Mad Cow threat. More of the healthier grass-fed animals are therefore found to be kosher after slaughter than feedlot raised cattle, by a ratio of about 2-1.