Fumigation
Want to know what toxin has killed thrives robbing houses? What pesticide is so poisonous it depletes the ozone layer?
This is the Pick Your Poison podcast. I’m your host Dr. JP and I’m here to share my passion for poisons in this interactive show. Will our patient survive this podcast? It’s up to you and the choices you make. Want to know what toxin has killed thrives robbing houses? What pesticide is so poisonous it depletes the ozone layer?
Today's episode starts in the emergency department. You walk past room 4 and see a 30 something year old man curled up in the fetal position on the stretcher. There’s vomit on his gown. His skin has a gray cast. Who is this guy? He doesn’t look good and you haven’t heard about him yet. You find the intern and ask her to present the case.
She says he’s 38, with a chief complaint of nausea and vomiting, onset a few minutes prior to arrival. He has abdominal pain, but no focal tenderness on exam to suggest pathology like appendicitis. He’s complaining also that his throat is burning, but his tonsils looked fine. He’s otherwise healthy and she thinks it’s likely food poisoning or gastroenteritis i.e. stomach virus. She thinks his throat is burning due to irritation from vomiting and gastric acid.
“We’re talking about the patient in room 4?” you ask. An hour of vomiting in a healthy person doesn’t match with the person you saw there. Either does gastroenteritis.
“Yes,” she says. “His vitals are temperature of 98.5 Fahrenheit or 36.9 Celsius. Heart rate 110, blood pressure is 120/80, respiratory rate of 20 and a pulse ox of 100% on room air.”
“Let’s go see him together,” you say. Her presentation and your glance from the doorway don’t match up. The patient is lethargic but wakes up at the sound of your voice. He gives you the same story. He denies significant past medical history, medicines, supplements, and tobacco, alcohol and drugs. You agree with the intern, his exam is unremarkable. His heart and lungs are normal, no abdominal tenderness. Good muscle strength, sensation intact.
The intern ordered IV fluids, and ondansetron or Zofran an antiemetic. Something isn’t right here, that said, we don’t have much else to go on. You tell the intern to await the lab and urine results and continue to monitor his symptoms. Maybe he'll improve with IV fluids and antiemetics. Possible. Or maybe the problem will progress, and we'll have a better sense of what additional work up might be useful.
An hour later, his basic labs, a complete blood count, and chem 7 come back normal. No sign of infection, anemia, dehydration, or kidney problems. They are completely unremarkable. The intern reports the patient doesn't feel any better. You return to the room to reassess him yourself. No change in his vitals, no change in his symptoms. The intern ordered a second bag of IV fluids and another dose of antiemetics. You tell him you’ll continue to monitor him.
Thirty minutes later, the charge nurse calls a code blue. “Room three?” You ask suspecting it's your patient with a heart attack.
“No,” she says “four.”
Maybe she's mistaken about the room, you rush over to find out. Why would an otherwise healthy 38-year-old with vomiting suddenly have a cardiac arrest? There's no mistake. The intern, in room 4, is standing on a stool doing CPR. The nurse pushes a dose of epinephrine.
“What happened?”
The nurse says she was giving a third dose of antiemetics. The patient was awake and talking to her when he suddenly said, I don't feel good and passed out. She couldn’t find a pulse and called the code.
“Time for a pulse check," she says looking at the clock. The resident stops compressions; you put your fingers on the patient’s neck. Nothing. No pulse. On the monitor, a wavy line crosses the screen, like a sign wave. It’s a distinctive type of ventricular fibrillation, called to torsade de points.
“Magnesium,” the intern says. You nod in agreement. The nurse pushes 2 grams as the intern restarts compressions.
The triage nurse comes into the room and says can I let the police officers back?
“What?” You say.
The police wanna come back, "she repeats.
For this patient with nausea and vomiting and now a cardiac arrest? No. you answer. Why are they here? Whatever the reason they can wait.
Two police officers walk into the room. Obviously, somebody else let them back.
“He gonna make it?” one of them asks.
“I don't know,” you respond. In hospital cardiac arrest has a survival rate of about 25%. On the one hand this patient is otherwise healthy, on the other, you have no idea what the heck is happening.
“He shouldn't a gone inside the tent, "he says to his partner.
“What?” You say. “Was he camping?” Even if he was, what does that have to do with this?
“Fumigation,” the officer says. “The medics didn't tell you? He was laying on the sidewalk across the street from a house covered in a huge fumigation tent.”
This completely changes the case. Question 1. It's time to pick your poison. Is it?
A. Carbon monoxide
B. sulfuryl fluoride
C. Chlorine gas
Answer: B. sulfuryl fluoride. Carbon monoxide is a great guess, and you can send a level just in case, but if it was CO, the patient should've improved once removed rather than progressively worsened. Chlorine gas is an irritant, causing respiratory failure amongst other things. In addition, it's not used as a pesticide. It’s more a weapon of mass destruction.
A number of dangerous gases are used as fumigating agents and we’ll come back to some of these, but in the US only one is legal for use in houses. And that's sulfuryl fluoride, you might know it by its brand name of Vikane.
Last week, I promised to tell you about methylbromide, it’s a gas, used in the past as a fumigating agent in houses. It does not cause bromism, what it causes are serious neurological problems, specifically generalized weakness, myoclonus, or muscle twitches, and altered mental status, ultimately leading to seizure, and death. Currently in the US it’s only for use in agricultural settings, greenhouses warehouses and ships. Why? Kind of interesting. Initially, restrictions were due to very valid concerns about toxicity, especially from an occupational standpoint. In 1992, researchers found methylbromide causes significant ozone depletion, so that’s when it’s use was really restricted.
After methylbromide exposure neurological deficits can be reversible, but many patients suffer long-term complications, including persistent deficits. Many have cognitive impairment, memory deficits, and difficulty with balance. There’s evidence even exposed workers without symptoms may have subtle neurocognitive deficits.
Phosphine gas is another very dangerous toxin used as a fumigant. Again, it's not allowed for residential use in the US, but worth mentioning because it’s used in other countries. Recently, several tourists died in a hotel room in Thailand, and it’s believed phosphine gas was responsible. In the US, still used to fumigate grain silos and rail cars. Tragically a child died, and several men were exposed after riding in a rail car and either not seeing or not reading signs posted warning of the danger.
This hospital and patient are in the United States, so if it's a house being fumigated, he’s been exposed to sulfuryl fluoride. And to clarify what do I mean by fumigation? If a house becomes infested with pests, often termites, and intensive treatment is required, then the entire house can be covered in a huge tent. They're often brightly colored, exactly like circus tents. The tents are airtight, the pesticide is infused inside the house and left for a certain duration of time, typically a few days. Then the tent is removed, and the house is aerated for another few hours or days, until it's safe for the family to return.
Does sulfuryl fluoride make sense here? Was our patient inside the house? Or is this a random coincidence? The fumigation tent is there for a reason, not just so the neighbors don’t complain about fumes. It’s necessary because the exposure is lethal. It can, and does, cause sudden cardiac arrest. More details in a minute, we need to focus on treatment first.
What now? To answer this, we need to answer question # 2.
What electrolyte disturbance does sulfurylfluoride cause? I'll give you a hint. It's similar to the electrolyte disturbance caused by hydrofluoric acid, so if you listened to the Burn episode, you know. It’s the reason both of these exposures are potentially lethal.
A. potassium.
B. magnesium.
C sodium.
D. Calcium.
The answer is D. Calcium. Regardless of the method of exposure, hydrofluoride acid or sulfuryl fluoride, in the body, fluoride binds up calcium. You ask the nurse to draw blood for a quick bedside calcium test. A minute later, your suspicions are confirmed. The calcium is extremely low.
The treatment? Calcium. Now if you remember from the Burn episode. We have two types of calcium gluconate, and chloride. Both can be given an IV. Calcium chloride has three times the calcium of calcium gluconate, but it carries the risk of cardiac arrest. In a stable patient we would give gluconate. Obviously, our patient is not stable so I'd move right ahead to calcium chloride. He’s already in cardiac arrest, you can’t make it any worse.
You order several amps of calcium and continue CPR. The heart rhythm alternates between v. fib, v. tach and torsade. You start a magnesium drip in addition to calcium and try another antidysrhythmic, amiodarone.
“Why was he in the house?” You ask the police.
Question 3. Patients have sustained sulfuryl fluoride exposures for which of the following reasons?
A. Theft
B. Suicide
C. Occupational exposure
D. All of the above.
Answer: D. All of the above. Fumigated houses have definitely been targeted by thieves. It’s a huge brightly colored circus tent advertising no one is home. Clueless thieves, with no idea of the magnitude of the risk, have entered and been poisoned. In one case report, a woman who wanted to commit suicide crawled in under a tent. Not surprisingly, there have been mishaps with workers who've been exposed unintentionally.
The police say your patient had a pillowcase with an iPad and a computer next to him on the sidewalk. Also in the pillowcase, an N95 mask and safety goggles. In fact, the police were notified by the homeowners after activity on security cameras in the supposedly empty house.
The patient still has no pulse. While you continue to resuscitate him, let's talk about what happens after sulfurylfluoride poisoning. After you inhale the gas, fluoride ions are released into the body. In reality, we don’t have a good understanding of what happens. We do know fluoride ions themselves are toxic and likely contribute to cardiac dysrhythmias. More importantly, fluoride binds calcium and magnesium, causing multisystem organ failure. Calcium is required for muscle contraction, remember your heart is a muscle. In addition, hypocalcemia causes QTC prolongation, we’ve discussed in the past, a risk factor for lethal dysrhythmias like ventricular tachycardia and torsade. It can also cause pulmonary edema and respiratory failure.
The patient has shown no signs of recovery. A repeat beside blood test shows high calcium and magnesium, due to your treatment. Sulfuryl fluoride is reported to affect potassium in some cases, but his is normal. He still has occasional ventricular tachycardia, but the rhythms progressed to PEA or pulseless electrical activity. Meaning occasional disorganized contraction of the heart, but not consistent with life and not strong enough even to produce a pulse.
What else can we do? Uggh. I always hate to say this, but not much. As usual we don’t have any randomized controlled trials, where half the patients are given a lethal poison to test treatment strategies.
The dangerous nature of this exposure is a big part of the reason safety precautions are actually mandated by law. One interesting point is that sulfuryl fluoride is a colorless odorless gas. Just like natural gas, used for cooking. Nevertheless, I’m sure everyone at some point has smelled a “gas leak” from the stove. Why? Because the gas companies add a smelly substance as a safety precaution. That way if there is a gas leak, hopefully someone will smell it. It's often methyl mercaptan, a substance with a rotten egg smell.
Similarly, in fumigation tents a second agent is added so that the lethal, colorless, odorless sulfuryl fluoride doesn't go unnoticed. In this case, it's generally chloropicrin. It’s not just smelly, it’s also an irritant. Meaning it causes burning, tearing eyes, a sore throat and can cause vomiting and diarrhea. It’s effects are felt immediately. This alerts anyone left inside or entering the tent mistakenly, to get out, keeping homeowners as well as workers safe.
Our patient had goggles and an N-95 mask. Why wasn’t that enough. Goggles might've helped prevent eye irritation from the chloropicrin. A mask isn’t enough for sulfuryl fluoride. You need a self-contained breathing apparatus to go in safely, a SCUBA tank essentially. Even then, there’s risk of leaking around the mask. Even a tiny exposure to sulfuryl fluoride is risky.
Cases of exposure are rare, most reports come from California and Florida. Why? Question #4.
A. Regulatory differences
B. Elevated ambient temperature
C. Number of infestations
Answer: C. The climate there is perfect for termites and thus house fumigation is not uncommon. I can’t tell you enough how dangerous this stuff is. There's a really tragic case of an elderly husband and wife who died within days of each other after their house was fumigated. The couple followed the rules, staying out until the exterminators ventilated the house for five hours after removing the tent, including running fans for recirculation. They were given permission to return. The next day, both the husband and wife felt weak with vomiting. 36 hours later, the husband had a cardiac arrest and died. He was elderly, so it didn’t raise any eyebrows. Five days later, the wife was admitted to the hospital with hypoxia and pulmonary edema, dying the next day from a cardiac arrest. At this point, suspicion arose. It was too late to test the husband, but in her case fluoride toxicity was confirmed with an elevated level.
What happened? Exterminators can actually test the air, to check the sulfuryl fluoride concentration. They are supposed to do so before allowing anyone back into the house. Unfortunately, in this case they didn’t. Enough sulfuryl fluoride remained for days despite otherwise airing out the house. Crazy. We call sulfuryl fluoride, a pesticide, but interestingly some refer to it as a biocide, meaning it'll kill anything and everything at a high enough dose.
One other treatment is a consideration. Hemodialysis can remove fluoride after hydrofluoric acid. You could consider it, but for acute sulfuryl fluoride exposure, the patient probably won’t be stable enough to get it.
Back to our patient. He’s been coding now for 50 minutes. You look around the room. The nurses are shaking their heads. You say the traditional last words in a code. “Anyone have any other ideas?” No one responds. The intern stops CPR and calls the time of death.
If we’d gotten the information about exposure earlier, would it have made a difference if we knew from the beginning? Might we have saved him? Almost certainly it wouldn’t have changed the outcome. It’s a tragic case, but unfortunately sulfuryl fluoride is an extremely dangerous toxin.
This is fictional, as are all our cases, to protect the innocent, but it is based on real poisonings.
Last question and today’s pop culture consult? What TV show featured the protagonists using a tented house as cover for illegal activities?
A. The wire
B. Breaking Bad
C. Sopranos
D. South Park
Follow the Twitter and Instagram feeds both @pickpoison1 for the answer. Remember, never try anything on this podcast at home or anywhere else.
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While I’m a real doctor this podcast is fictional, meant for entertainment and educational purposes, not medical advice. If you have a medical problem, please see your primary care practitioner. Until next time, take care and stay safe.