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Iodine levels in teat dip a matter of debate

Dave Wilkins Published on 18 May 2012

No one questions the need for teat dip. It’s one of the most important products in the milking parlor and a key to protecting your cows’ udder health and your dairy’s milk quality.

But the amount of iodine in commercial teat dip formulations is very much up for debate these days. The question is whether dairymen are getting what they’re paying for, says Allan Britten, president and laboratory director at Udder Health Systems.

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“It may not be an issue of efficacy or cow safety or animal health, but of value,” Britten says.

The controversy is centered around the way manufacturers measure the iodine content in teat dip.

Manufacturers use a common laboratory process called “titration” to determine the concentration of iodine in their formulations. The resulting measurement is sometimes referred to as “titratable” iodine or “available” iodine.

For decades, manufacturers used a single method to measure titratable iodine. However, in recent years chemists at some manufacturers have begun to use a strong acid such as nitric acid or hydrochloric acid as an additional step in the process.

The problem is that the two different methods can yield significantly different results, Britten says.

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“It puts some products potentially at a competitive disadvantage versus others,” he says. “A product measured by one method would show a lower iodine content than the same product measured by the other method.”

For example, there are some teat dip products labeled at 1 percent that could measure 1 percent titratable iodine using one test method but only .8 percent using the other method.

“There are other products out there labeled at 1 percent and when you run the test on them, one method shows it at 1 percent and the other at 1.3 percent,” Britten says.

There’s nothing wrong with using either titration method, but the situation has created confusion and the potential for dairymen to be misled.

“If you’re a company using a method that labels the product as having 1 percent iodine, but it would be labeled 20 percent less content by the other method, then some people would say you’re selling something that isn’t there,” Britten says.

So what’s a producer to do? For starters, they could ask to see laboratory test results from both titration methods.

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“That’s one way they could get a better handle on the value question,” Britten said.

Udder Health Systems now routinely uses both methods when testing for titratable iodine in its clients’ teat dips.

“Because of the disparity that exists in the market, I think the only answer is that you have to look at both numbers if you’re doing comparison shopping,” he says.

The U.S. Pharmacopeia accepts both methods.

Critics of the acidification method say it’s not an accurate reflection of the way teat dips are actually used on the farm. After all, nobody puts acid on their cows’ teats.

On the other hand, the most current recommended laboratory methodology involves the addition of hydrochloric acid to perform the test.

“It’s fair to say there is legitimate marketplace angst over the fact that these two methods are trying to coexist in the marketplace,” Britten says.

Manufacturers are trying to figure out how to respond to the situation.

“One approach would be to change the labels to reflect what the value would be with the most favorable method. Then they wouldn’t be at a competitive disadvantage,” Britten says.

Another possibility would be for manufacturers to simply lower the iodine content in their products to match the level of their competitors.

“They would be able to save millions of dollars in iodine content,” Britten says.

“Iodine is expensive. The world price of iodine is climbing, so there is pressure on the manufacturers to keep their products attractively priced.”

The U.S. Food and Drug Administration regulates teat disinfectants as over-the-counter drugs. However, the FDA does not require proof of effectiveness for labeling, and no government agency has stepped forward to assume authority over titration methods in the laboratory.

“This controversy is occurring in the absence of a regulated standard,” Britten says.

Many industry participants, including Britten, aren’t eager for the government to get involved.

Scientists in private industry probably have more expertise on the subject than government scientists, he says.

“Actually, it’s not in anybody’s interest to get the government to weigh in on it,” Britten says. “It would be better if the industry just resolved this internally but, so far, that hasn’t happened.”

The dairy industry has managed to resolve similar conflicts in methodology on its own.

As an example, Britten cites the controversy years ago about measuring airflow on dairy vacuum pumps. It seems there was no standard way to measure cubic feet per minute.

“That was highly controversial, with people yelling at each other, people figuratively beating each other up in the marketplace,” he says. “There was no common reference point to test that product.”

It took years, but the industry finally agreed on a standardized method.

“We now have standardized methods of measuring (CFM) and the controversy has basically disappeared,” Britten says.

The same thing could happen with iodine content in teat dips.

Dairymen can only hope. PD

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