GRAND RAPIDS, Mich. (WOOD) — Fifty years ago, a shipping error led to a major environmental disaster in Michigan that not only led to the death of more than a million farm animals but also passed along a highly toxic contaminant to virtually everyone who lived in Michigan.

Instead of magnesium oxide, Michigan Chemical in St. Louis accidentally shipped polybrominated biphenyl (PBB) to the Michigan Farm Bureau’s processing facility in Battle Creek. The products, Nutrimaster and Firemaster, not only sound alike, but the two products — a white, clumpy compound — could also be easily confused for one another.

Thanks to the diligent work of one West Michigan farmer and his allies, state agencies were eventually able to figure out what happened and quarantine specific farms. Michigan Chemical and the Farm Bureau put together a $15 million insurance pool to help farmers who lost their herds and their herd’s production, but the disaster was far from over.

While the first animals dealt with sudden PBB toxicity, other farmers watched as the symptoms continued long after the tainted feed was removed and after the farm bureau’s machinery was deep cleaned. Farmers and scientists were seeing the impacts of low-level, long-term contamination.

Testing showed that cattle, though clearly sick and dealing with PBB toxicity, tested at a low enough level to be considered safe for human consumption. With the insurance pool dried up, hundreds more farmers faced financial ruin and a dark dilemma: lose their investment entirely or salvage what they can by selling sick animals to market and pass along the PBB.

In the shadow of it all, a team of lawyers and one committed veterinarian kept pushing for accountability.


Alpha “Doc” Clark personified your stereotypical Michigan farmer — a quiet, stocky man with a strong work ethic — except he wasn’t a farmer. He grew up on a farm. His father and brothers were all farmers. But Clark felt a different calling, to work with animals as a veterinarian, earning his nickname by graduating from the Michigan State University vet school.

Living on the outskirts of McBain — a tiny city tucked away in Missaukee County not far from Cadillac — he quickly became one of the region’s most popular vets, brought in by farmers across the area to tend to their animals. Clark died in 2022. In his obituary, it says Clark answered farm calls “at anytime of the day or night, 7 days a week.”

But he loved nothing more than taking care of cows. He told Joyce Egginton in her book, “The Poisoning of Michigan,” that tending to cows was his true passion.

“It is the nicest thing in the world, doctoring cows,” Clark said. “A cow is the second mother in the world. She feeds all our babies, and hers is the most perfect food on the earth.”

By the summer of 1974, more than a year after the erroneous shipping error that sparked the mess, Clark had barely heard of PBB. He hadn’t heard of any farms in his region that were quarantined and the local chapter of the Farm Bureau insisted that it did not receive or handle any tainted feed.

But Clark knew something was wrong. He was seeing more and more calls about sick cows, dealing with issues that he couldn’t pin down.

“It bothered the hell out of me that they would not respond to treatment,” Clark told Egginton. “It was a subtle situation and I couldn’t get a hold on it. It was like trying to catch a snake in the sorghum. You grasp him by the head and then by the tail and still he gets away from you.”

Clark took the challenge personally. If he couldn’t come up with an answer or a treatment within a few visits, he would stay on the problem and keep coming back for free until he cracked the case. But eventually, it shook his confidence.

“I had plenty of experience and I still had plenty of energy, so I should have been at my peak professionally. But I couldn’t seem to do anything right,” he said. “Some of the farmers got so they quit calling me. … I had always had a good rapport with my clients, but all of a sudden, they (were) getting this feeling of uncertainty about me.”

Clark said he doubled down on his work, spending more and more money on different drugs. He spent the entire summer dedicated to the region’s cows, but that work didn’t seem to pay off. It wasn’t until a trip to the Newaygo County Fair that he started to realize something bigger was at play.

Clark and his brother drove to Fremont to judge cattle at the fair, and he was stunned by what he found.

“He was amazed to find a dearth of decent cattle at the Newaygo fair, which was always a good one, and that several experienced breeders in the area were not exhibiting,” Egginton wrote. “He also caught undertones of arguments, not meant for his ears, about whether animals from some farms should have been allowed at the fair because of uncertainty about ‘it’ being contagious.”

After a handful of prodding conversations, Clark learned that several farms in Newaygo County had been quarantined because the herds ate contaminated feed from the Fremont Co-Op. Then, he heard about the symptoms — the same ones he was seeing all summer.

“I realized not only my clients’ cattle was poisoned, but their land and their bodies were poisoned,” Clark told Egginton. “I didn’t know what to tell them. Since no one would admit there was PBB in their feed, I could have advised them to cover up and ship their cattle to market while they could make a few bucks. Or I could have tackled the problem. Well, I tackled it.”


In the shadow of President Richard Nixon’s Watergate scandal, many Michigan farmers started referring to the disaster as “Cattlegate.” Harry Iwasko, the then-assistant attorney general of Michigan, didn’t think it was a coverup as much as an incident that highlighted the state’s sheer unpreparedness to oversee a problem of this magnitude.

“It was not what was done that was wrong, but what was not done by a number of people in authority who did not realize the magnitude of the problem,” Iwasko told Egginton. “If I go back over the whole thing day by day and think how we might have acted differently, I do not think we could have done better than we did. Within the power that we had; I believe we did a commendable job.”

Dr. Tom Corbett, who helped farmer Rick Halbert discover the root cause of the PBB disaster, likely didn’t agree with the last claim, but certainly agreed with the former.

“It was obvious to me that none of the state agencies knew what they were doing,” Corbett told Egginton. “PBB was being recycled many times over in all kinds of ways, nothing was being done to prevent it, and nobody really knew what was in the chemical.”

While farmers fought for help, Clark discovered that the testing regimen the state was using to determine PBB levels was completely untrustworthy. While working with Missaukee County farmer Garry Zuiderveen, Clark noticed that some samples varied drastically in results. He took 13 samples from one cow and sent them in for testing. He received 13 different results.

“It proved to us this was only a litmus test which showed whether the compound was present in the animal, but it gave no insight as to the damage done,” Clark said. “There were so many variables. The concentrations of PBB must have varied in different batches of feed, and the chemical itself must have varied from one batch to another. What you found in an animal when you tested it wasn’t all that relevant.”

Clark and Zuiderveen also discovered that farmers were sending the wrong animals in for testing. Originally, they tested the cows that showed the worst symptoms. But those animals were sick because their bodies had already absorbed or processed most of the PBB. The PBB levels were higher in animals where the PBB was sitting idle, stored in the animal’s fat.

“So long as the toxin was quiescent in an animal’s body fat it appeared to do little harm, but as soon as the animal mobilized its fat to cope with stress, then the PBB began to devastate its system,” Egginton explained. “The most common stress for dairy cows is pregnancy and calving, and this — in the experience of most farmers — was when the worst toxic problems were manifested.”


As the PBB disaster started to unfold, the Food & Drug Administration announced its first human safety standard — setting the tolerance level at 1 part per million. The agency settled on that number not because they knew that anything lower is safe but because tests at that time couldn’t find the compound below 1 ppm.

However, it was soon clear that animals with rates below 1 ppm in their bodies were still extremely sick and showing notable symptoms. Within six months of the FDA’s announcement, a new testing method was found, and the standard was again lowered to the lowest available threshold, .3 ppm.

The new threshold allowed the state to quarantine more farms, but the funds to help those farmers suddenly stuck with quarantined cattle was virtually gone. Most of that money was sucked up by the farms that were hit first with large quantities of PBB. By November 1974, Halbert had received a “handsome settlement,” his worst cattle were sent to the burial pits set aside in Kalkaska County, and his farm was back up and running and selling milk.

But hundreds of others, mostly farmers dealing with low-level contamination — but contamination nonetheless — faced a question that shook them to their core: Do you stop the flow of PBB and take the financial hit by killing and burying your herd? Or do you earn what you can and knowingly sell your sick cattle to market and allow the PBB to be passed through the food chain?

With the insurance pool running low, settlements grew smaller and smaller. The farmers had no choice but to take action and file a lawsuit. Two lawyers from West Michigan led the fight, with Doc Clark providing support.

Paul Greer was a successful attorney in Fremont who operated a 500-acre farm out of the sheer joy of farming. He teamed up with a young lawyer from Grand Rapids named Gary Schenk. According to Egginton, the two started working on PBB cases in the summer of 1974, shortly after the first quarantines were announced. By the summer of 1975, 580 different small farmers had filed claims of financial hardship, and Schenk and Greer represented more than 80 of them.

The lawsuits proved to be a long, uphill fight and in some cases dangerous. Greer, Schenk and Clark each shared stories of being harassed. Schenk’s wife recalled getting phone calls in the middle of the night threatening the family’s children. Clark said the sheriff told him to carry his rifle in his car with him, and for a while he did.

While Clark was never actually attacked, his reputation was taking a hit. At one time, a senior official with the Michigan Department of Agriculture allegedly accused Clark of tampering with the fat samples. In another incident, Clark claimed the agency tried to trick him into shipping samples out of state without proper authority. He could have lost his license to practice as a veterinarian if he didn’t have the foresight to record his phone calls and show that he had done everything properly.

Alongside Clark, Schenk and Greer would focus on a farm that they believed had the strongest case. But as each trial loomed, the defense would beef up its deal and convince the farmers to settle out of court. Clark had a hard time blaming them. A settlement ensured the farmers that they could pick up the pieces. There were no guarantees in going to court.

Eventually, the trio found the family that would test its luck, Roy and Marilyn Tacoma. They lived in Falmouth, about 10 miles east of Cadillac. Like previous cases, they were offered a settlement a few days before the start of the trial, but the family refused.

“Ours was one of 84 similar cases on which Schenk and Greer had put in months of preparation,” Roy Tacoma told Egginton. “I felt I was a bit privileged to have been picked from all these for a court trial. If I had settled, where would the other 83 cases have gone? The defendants could have done the same thing to them — waited until each one was ready for trial and then offered just enough to persuade them to drop the suit. That way, they could have taken 20 years to settle with the farmers. I figured that it was worth spending six weeks on a trial, so that our settlement would set a pattern for the others.”


The plaintiff’s team opted for a bench trial, hoping to persuade the judge for a ruling instead of leaving it up to jury. They seemed happy to let Judge William Peterson oversee proceedings. According to Egginton, the 53-year-old was considered a strong jurist with a good record and the lawyers were pleased with how interested he appeared to be in the minutia of the evidence.

But Tacoma’s expectations were blown away. The trial didn’t last six weeks — with some lengthy breaks mixed in, it lasted more than 14 months — from February 1977 to May 1978. It generated more than 25,000 pages of manuscript. Tacoma and the other witnesses walked through his herd’s problems in minute detail, everything from the lost calves and developed deformities to random spurts of blindness. Even as the trial went on, Tacoma could only earn back a fraction of his investment. Because of quarantine limits, he was only able to sell milk and it had to be mixed down into skim milk to become FDA compliant.

Marilyn Tacoma also testified to the role that PBB exposure played in her family. Just like the cows, Marilyn suffered from strange fainting attacks, random moments of blindness and uncontrollable diarrhea. Her children routinely complained of foot and joint pain and extreme fatigue.

Experts from around the world were brought in to talk about the characteristics of PBB and whether this exposure would cause the issues at hand. Much of the counterargument relied on a set of experiments funded by the FDA, one that also received contributions from Michigan Chemical and the Farm Bureau. That study put together an experimental farm of Holstein cows — 40 from Wisconsin and 40 from Michigan. The Michigan cows had previously eaten PBB-contaminated feed and as of 1976 still had traces of the compound in their bodies. However, the study found no major health differences between the two herds.

Schenk, Greer and the plaintiffs were surprised that a judge would lend so much credence to a study funded directly by the defense, but the shocking ruling made it clear that Judge Peterson was far from convinced that PBB hurt Tacoma’s herd.

Nearly six months after testimony wrapped up, Peterson announced his decision. He dismissed all claims against Michigan Chemical and Farm Bureau Services and ordered the plaintiffs cover court costs. In his 155-page ruling, he stated the Tacomas failed to prove that low levels of PBB in their herd had been harmful, even going as far as to say “in small amounts, PBB is not toxic” and that the “greatest tragedy of the contamination had been the ‘needless destruction of animals exposed to low levels of polybrominated biphenyl.’”

Peterson’s ruling danced around the argument that some farmers and supporters of the Farm Bureau had loudly echoed behind the scenes. He painted the Tacomas as another family trying to cash in on the “PBB scare” and called some of the research presented by the plaintiffs, not the defendants, as “suspect.” He specifically singled out Clark.

“Plaintiff’s counsel picture ‘old Doc Clark’ as just a country vet uninterested in litigation, concerned only with treating cows, and too busy doing that to keep records or to prepare to testify,” Peterson wrote. “The trial picture, however, is that of a man who, on learning about PBB, leaped to a phobic conviction that is was causing every ailment seen in his clients’ animals, and devoted his complete energy to the dual cause of being against sin (PBB) and aiding his clients and other claimants in obtaining financial settlements from the defendants.”

About a year following the ruling, Schenk and Greer were presented with a settlement for Tacomas and the rest of their claims, earning less than $40,000 per farmer. Egginton called it a “pittance” but one that the farmers and lawyers felt forced to accept, because the alternative was likely much less if anything.

Egginton maintains that Peterson misunderstood the concept at hand; that he could not differentiate the difference between sudden PBB toxicosis and the complications caused by low-level exposures. Peterson pointed to Clark’s own testimony, saying “there was no correlation between observed symptoms and his autopsy findings.”

Further studies, including those done by the experts behind the Michigan Long-Term PBB Study, found that the amount of PBB in an animal or person’s tissue did not necessarily correlate to the severity of symptoms. Everybody is different and there were so many variables at play that any correlation between symptoms could be lost in the mix. But studies still clearly show that PBB exposure has a wide array of negative health effects.

Now long into the shadow of Peterson’s ruling, many members of the farm community still consider Doc Clark a hero, not simply for sacrificing his time and talents to help his clients, but for doing what he believed was right.

Clark continued on as a respected veterinarian across Mid-Michigan, working as a vet for more than 60 years. But his work during the PBB Disaster will always be a defining role, even if his work didn’t result in a win in the courtroom.

He reflected on his work, telling Egginton, “Perhaps it makes you fight the harder. It’s tragic and it ain’t right. There was no justice.”

This story is the third of a four-part series. You can find the first two parts of the series here.