I first got interested in the history of the English town of Bath years ago when I had the pleasure of sitting in the famous “Pump Room,” sipping a glass of Bath water. A brochure on the table told of the health benefits attributed to drinking or bathing in the water that bubbled up from a spring just below. What really captivated me, though, was the story about treating lead poisoning by immersion in the water!
As early as the first century, Roman author Pliny the Elder noted that lead mining was dangerous and even described stomach pain and muscular problems that afflicted the miners as symptoms of lead poisoning. Lead toxicity was common in Rome due to the use lead dishes and the consumption of wine sweetened with “sapa,” which is lead acetate that forms by storing vinegar in lead vessels. Our word “plumber” is derived from “plumbum,” the Latin word for lead since the Romans used lead in plumbing. The pipes that conducted water atop the aqueducts were made of the metal, leading to widespread exposure. “Plumbum” also explains the chemical symbol being Pb for lead.
In 1703, English physician William Musgrave described an epidemic of abdominal pain, constipation and vomiting that was often followed by paralysis of the arms in the English county of Devonshire. Since the area produced copious amounts of apple cider, he attributed “Devonshire colic” to cider that had turned acidic. He was right about the cider, but wrong about acidity being the problem. The colic was caused by lead in the cider!
The true cause of the colic was finally identified in an epic 1767 publication by another physician, Sir George Baker, who compared the lead content of Devonshire cider with that of other ciders. It turns out that lead was being leached out from solder used in the distillation equipment as well as from lead used to repair cracks in the cider press. The acidity argument wasn’t totally wrong either. Cider turns sour when it is invaded by microbes that turn its alcohol content into acetic acid and lead dissolves more readily in an acidic solution.
Now let’s get to the Bath story. Bathing in the waters of the spring has been well documented since Roman times and by the Middle Ages accounts had emerged about the special healing properties of the water. Naturalist William Turner, who is best known for publishing the first herbal written in English rather than Latin, turned his attention to the healing powers of the waters of Bath in a book published in 1568. He noted that constipation, abdominal pain, and even some types of paralysis were known to improve by bathing in the water. Turner didn’t realize it, but he had described the symptoms of lead poisoning! The town of Bath even had a display of discarded crutches as evidence of cripples being cured by having immersed themselves in the water.
By the 17th century, word had gotten around that anyone suffering from paralysis after a bout of colic should head for Bath. Physicians in the town were said to have noted that some of the afflicted were actually being cured! Many of the sufferers who came to Bath were poor and ended up as beggars. A town committee was formed to tackle the problem and recommended that money be raised to establish a “charity” hospital to keep the sick from becoming vagrants. The idea was at first rejected but took root when it was proposed that the hospital be used to document the healing properties of the water in a scientific fashion. This would then attract well-to-do patients who would increase the town’s prosperity. The Bath General Hospital opened in 1741 with a “trial of the waters” being a goal. The hope was that recording the results experienced by patients, especially those who had come with complaints of colic and paralysis, would provide “indisputable evidence” that Bath waters were beneficial for patients, and as a consequence, for the health of the town of Bath as well.
From 1760 to 1879 records were carefully kept, particularly for patients with symptoms of lead poisoning. Historically, this represents the first long-term trial of any medical therapy! During these 120 years, 3,377 patients with suspected lead poisoning based on their symptoms were admitted with 45% eventually being discharged as “cured.” An astounding result! Sitting in warm water had always been considered to be a pleasant experience, but how could it cure lead poisoning? That question faded away by the end of the 19th century because the toxicity of lead had become well known and serious cases of lead paralysis dwindled as people learned to avoid exposure to the metal.
It would take another hundred years until the question was raised again, this time by Audrey Heywood, a kidney disease researcher at the University of Bristol. She offered an interesting theory to explain the healing effect of immersion in water. Treatment at Bath involved sitting neck deep in water, not just once, but daily for months! As anyone who has dived down while snorkeling knows, water pressure increases with depth. Heywood suggested that immersion in water puts pressure on the legs and abdomen and squeezes fluid into blood vessels in the chest area that in turn triggers secretion of a hormone called atrial natriuretic peptide that causes an increase in urinary volume. Again, anyone who has treaded water for a time knows about the urge to urinate.
An increase in urine volume results in an increase in calcium excretion. Since the body handles calcium and lead the same way, Heywood’s theory was that the excretion of lead should also be increased with an increase in urinary volume. Indeed, the toxicity of lead is due to the body mistaking it for calcium which it wants to absorb because it is needed for bone formation, blood clotting, nerve signaling and heart and muscle function. Replacement of calcium with lead impairs all these processes.
A theory is just a theory until it is put to a trial which is just what Audrey Heywood and colleagues planned to do. Since you cannot ethically administer lead, they needed some subjects who were expected to have blood lead levels higher than the general population. Luckily, Bristol had a “Shot Tower” that is used in the manufacture of lead shot by dropping bits of molten lead into a water basin. Three workers from the tower with slightly elevated lead levels volunteered for the experiment that involved immersion in warm water for three hours, getting out at hourly intervals to empty their bladders and drink some water.
The volume of urine produced was significantly more than what is normally voided in a three-hour period and the lead content of the urine during immersion increased when compared with pre-immersion urine. The amount of lead excreted compared to the total body lead was small, but patients at the Bath Hospital did not immerse themselves for just three hours. A common regimen was three times a week for twenty-four weeks, so conceivably a significant amount of lead could have been excreted. Part of the “cure” could also have involved drinking the water that is naturally high in ions of calcium and iron, both of which tend to minimize the uptake of lead from the gut. Add to this that admission to the hospital also removed the patient from whatever had caused the lead exposure, be it occupation or contaminated food or beverage, and we have a possible explanation for the success of treating lead poisoning at the Bath Hospital.
The “trial of the waters” did accomplish the goal of attracting not only the victims of lead poisoning but the rich and famous to Bath as well. They sat immersed in the water, fully clothed for modesty, hoping to derive health benefits. They feasted on hot buttered “Sally Lunn buns,” a unique Bath delicacy that dates back to the 17th century when Sally first started baking them in a special oven reminiscent of our wood-fired bagel ovens. If you ever visit Bath, you must have one! I can attest to their gustatory appeal. And you can immerse yourself in the waters of the spring and enjoy the warm water. Who knows, you may even feel better after. But don’t count on being “detoxified.” I didn’t get a chance to try the water, but my daughters did immerse themselves in the bathtub in the hotel. They still remember taking a bath in Bath! And eating Sally Lunn buns.
