Mercury dangers rare, but remain

By Dr. John Koch

Question: A few weeks ago, the Southeast Missourian newspaper ran an article on people who might be getting mercury poisoning by eating too much fish. The gist of the article was: "How much mercury in fish is too much?" The article pointed out that: "Mercury warnings for U.S. lakes, rivers and coastal regions increased 115 percent from 1993 to 2001. There are almost 2,000 mercury-in-fish warnings on various water bodies in 44 states." The article focused on several individuals who apparently had mercury-related health problems because of consuming large amounts of fish in their diets.

My cat only seems to want to eat commercially available pet food made from fish. Should I be concerned about mercury poisoning in my cat?

Answer: I contacted the two leading manufacturers of pet food in the United States, and both assured me that they routinely check their foods for mercury. I was told that any mercury present was below measurable amounts and that their food was safe. Reports from several veterinary colleges and individuals associated with them indicated that mercury poisoning is virtually unheard of or at least unrecognized in our country at this time.

Could mercury poisoning become a problem if we are not careful? You bet it could! In the 1950s in Minamata City, Japan, an environmental catastrophe began that is still going on today. This fishing village started noticing that cats were acting strangely. They would go into fits of uncontrollability, frothing at the mouth and showing signs of impaired motor function. These cats would become so bad that they would literally stagger off into the ocean and drown. The disease was at first called the "disease of the dancing cats," and no one paid that much attention until a few years later when people started showing similar symptoms.

It was eventually discovered that the source of the problem was a chemical manufacturing plant that had been dumping mercury into Minamata Bay. The primary food for both cats and humans in the area was fish taken from the ocean near the bay.

According to a report in the (London) Guardian newspaper last year, there have been 2,264 confirmed victims of Minamata disease, as it is now called. Of the confirmed victims, 1,435 have died. Another 17,128 have applied for recognition as being victims. It is estimated that another 20,000 will apply for recognition.

The Minamata disaster is well documented and is an interesting twist of denials, delays and politics played out over 50 years. It also points out that concerns for a healthy environment and food safety cannot be taken for granted.

Dr. Koch is a Cape Girardeau area veterinarian.