رونوشت 🔗
WEBVTT
00:00:08.080 --> 00:00:11.359
Every parent wants to make the best decision they can for their child.
00:00:11.519 --> 00:00:15.679
But good decisions require more than strong opinions, they require good information.
00:00:15.839 --> 00:00:17.039
Welcome to Deep Dives.
00:00:17.120 --> 00:00:17.440
I'm Dr.
00:00:17.519 --> 00:00:23.519
Justin Smith, a pediatrician, dad, and someone who spent years helping families navigate difficult medical questions.
00:00:23.760 --> 00:00:28.239
Today's episode tackles one of the most emotionally charged questions in the vaccine conversation.
00:00:28.480 --> 00:00:30.160
What's actually in vaccines?
00:00:30.399 --> 00:00:34.479
If you've ever seen an ingredient list online and thought, wait, why is that in there?
00:00:34.719 --> 00:00:35.520
You're not alone.
00:00:35.679 --> 00:00:43.520
Today we're going to slow down, look at the science, and explore why a handful of unfamiliar names have become some of the most debated words in modern medicine.
00:00:43.840 --> 00:00:51.280
Imagine it's late at night, the house is finally quiet, your kids are asleep, you're scrolling through your phone, but a post catches your attention.
00:00:51.439 --> 00:00:53.840
It's a picture of a vaccine ingredient list.
00:00:54.079 --> 00:00:56.399
Several words have been circled in bright red.
00:00:56.719 --> 00:01:00.799
Mercury, aluminum, formaldehyde, polysorway 80.
00:01:00.960 --> 00:01:06.079
Across the top of the image, bold letters ask, why would anyone inject these chemicals into a baby?
00:01:06.319 --> 00:01:07.920
Thousands of comments follow.
00:01:08.159 --> 00:01:11.040
Some people say these ingredients prove vaccines are dangerous.
00:01:11.280 --> 00:01:12.560
Others laugh at the question.
00:01:12.799 --> 00:01:14.799
Some accuse doctors of hiding the truth.
00:01:14.959 --> 00:01:17.680
Others accuse parents of believing conspiracy theories.
00:01:17.840 --> 00:01:25.439
The conversation becomes louder, angrier, more divided, and somewhere in the middle of all that noise, one simple question gets lost.
00:01:25.680 --> 00:01:27.439
What are these ingredients really?
00:01:28.000 --> 00:01:33.120
Not what someone on social media says they are, not what a headline claims or not what a meme implies.
00:01:33.280 --> 00:01:33.920
What are they?
00:01:34.079 --> 00:01:35.200
Why are they included?
00:01:35.439 --> 00:01:36.560
How much is actually there?
00:01:36.640 --> 00:01:42.480
And perhaps more importantly, does seeing a familiar chemical name automatically tell us whether something is harmful?
00:01:42.719 --> 00:01:51.280
Those are the questions we're going to answer today, not by dismissing concerns, not by sensationalizing them, but by slowing down long enough to understand them.
00:01:51.760 --> 00:01:53.519
Why this conversation matters?
00:01:53.840 --> 00:01:59.920
One of the hardest parts about talking about vaccine ingredients is that everyone walks into the conversation carrying different mental pictures.
00:02:00.079 --> 00:02:05.040
When you hear the word formaldehyde, you might think of high school biology class or funeral homes.
00:02:05.200 --> 00:02:08.960
When you hear mercury, you probably picture the warnings about eating certain kinds of fish.
00:02:09.199 --> 00:02:12.319
When you hear aluminum, maybe you think about cookware or soda cans.
00:02:12.479 --> 00:02:14.639
Those mental connections happen automatically.
00:02:14.800 --> 00:02:16.719
Our brains are designed to recognize patterns.
00:02:16.800 --> 00:02:21.439
If we've heard a substance can be dangerous somewhere, it's natural to wonder whether it's dangerous everywhere.
00:02:21.599 --> 00:02:23.280
That's not irrational, it's human.
00:02:23.360 --> 00:02:32.080
And honestly, if someone told you your child was about to receive an injection containing ingredients you've only ever heard described as harmful, I'd actually expect you to ask questions.
00:02:32.400 --> 00:02:34.000
Curiosity isn't the problem.
00:02:34.159 --> 00:02:36.159
In medicine, curiosity is a strength.
00:02:36.319 --> 00:02:39.599
The challenge is making sure we don't stop at the first answer we find.
00:02:40.800 --> 00:02:48.560
One reason this topic creates so much anxiety is that our brains tend to think in categories safe or dangerous, good or bad, or poison or medicine.
00:02:48.800 --> 00:02:51.280
But that shortcut serves us well most of the time.
00:02:51.680 --> 00:02:55.919
If someone handed you a glass label of mercury, you wouldn't stop to calculate how much was in it.
00:02:56.240 --> 00:02:57.680
You'd simply say, no thanks.
00:02:58.000 --> 00:03:00.719
That's because human beings evolved to avoid obvious threats.
00:03:01.199 --> 00:03:04.159
Our ancestors didn't survive by performing chemistry calculations.
00:03:05.120 --> 00:03:07.120
They survived by recognizing danger quickly.
00:03:07.599 --> 00:03:10.159
The problem is that biology is rather rarely that simple.
00:03:10.639 --> 00:03:14.319
In medicine, there are four questions that matter just as much as the name of the substance itself.
00:03:15.120 --> 00:03:21.280
How much is in there, what form is it in, how does it enter the body, and what does the body do with it once it's there?
00:03:21.919 --> 00:03:27.360
These four questions are the foundations of toxicology, the science of understanding how substances affect the body.
00:03:27.840 --> 00:03:32.000
Because almost every substance can be helpful under some circumstances and harmful under others.
00:03:32.560 --> 00:03:36.639
Water keeps us alive, but too much water in a short period of time can be dangerous.
00:03:37.280 --> 00:03:39.599
Iron is essential for making healthy red blood cells.
00:03:39.919 --> 00:03:41.759
Too much iron is definitely toxic.
00:03:42.319 --> 00:03:49.439
Oxygen is necessary for life, yet patients receiving very high concentrations of oxygen for prolonged periods can develop oxygen toxicity.
00:03:50.000 --> 00:03:55.520
Even
Load full transcript
sunlight, the things that helps our bodies produce vitamin D, can damage our skin if the exposure is excessive.
00:03:56.159 --> 00:04:04.719
The lesson isn't that water, iron, oxygen, or sunlight are dangerous, it's that dose matters, context matters, the route of exposure matters, and the chemical form matters.
00:04:04.879 --> 00:04:11.439
These principles apply whether we're talking about medications, environmental exposures, food, or vaccines.
00:04:16.160 --> 00:04:27.839
So today we're going to examine four names that have become almost synonymous with vaccine debate aluminum, thimerosol, which is a preservative that contains a form of mercury, formaldehyde, and other preservatives.
00:04:28.160 --> 00:04:38.879
We'll ask why they're used, how much is actually present, how those amounts compare to what our bodies encounter every day, and where legitimate scientific concerns end and common misunderstandings begin.
00:04:39.120 --> 00:04:42.639
Because one thing I've learned after years of talking with families is this.
00:04:42.959 --> 00:04:46.560
Most parents aren't afraid of ingredients because they've spent years studying chemistry.
00:04:46.720 --> 00:04:48.800
They're afraid because they recognize the names.
00:04:49.040 --> 00:04:54.240
When we recognize a name without understanding its context, our brains naturally fill in the blanks.
00:04:54.480 --> 00:04:56.800
Sometimes correctly, sometimes not.
00:04:57.040 --> 00:05:06.959
By the end of today's episode, my hope isn't that you'll memorize the chemistry, it's that you'll have a framework for thinking about ingredient lists, not just in vaccines, but in medicine more broadly.
00:05:07.120 --> 00:05:12.319
So let's begin with the ingredient that probably generates more questions than any other, aluminum.
00:05:16.560 --> 00:05:22.399
So let's start with the ingredient that probably comes up more than any other in conversations about vaccine safety, aluminum.
00:05:22.560 --> 00:05:26.560
If you spent any time reading about vaccines online, you've probably seen claims like these.
00:05:26.800 --> 00:05:28.480
Aluminum is a neurotoxin.
00:05:28.639 --> 00:05:30.959
Why would we inject aluminum into babies?
00:05:31.120 --> 00:05:34.319
Our ancestors didn't receive aluminum, so why should our children?
00:05:34.480 --> 00:05:38.720
Those are understandable questions, but before we can answer them, we have to ask a different question.
00:05:38.959 --> 00:05:41.680
Why is aluminum in some vaccines in the first place?
00:05:41.920 --> 00:05:46.800
Because the answer isn't because it's harmless, and it isn't because no one has found a better option.
00:05:47.120 --> 00:05:49.439
The answer is actually much more interesting.
00:05:49.920 --> 00:05:54.079
Aluminum is added because it has the job as an adjuvant.
00:05:54.879 --> 00:05:57.600
So here's a little story that might help you understand what this is.
00:05:57.759 --> 00:06:00.000
Imagine you're a teacher standing in front of a classroom.
00:06:00.160 --> 00:06:03.680
Half the students are paying attention, the other half are staring out the window.
00:06:04.000 --> 00:06:08.000
You could repeat yourself louder, or you could do something that gets everyone's attention.
00:06:08.160 --> 00:06:12.720
Maybe you dim the lights, maybe you clap your hands, maybe you write something unexpected on the board.
00:06:12.959 --> 00:06:17.439
You haven't changed the lesson, you simply made it more likely that your students will notice what's important.
00:06:17.600 --> 00:06:20.480
And that's exactly what aluminum does in certain vaccines.
00:06:20.639 --> 00:06:22.160
It acts as an adjuvant.
00:06:22.560 --> 00:06:26.079
An adjuvant is a substance that helps the immune system pay attention to the vaccine.
00:06:26.240 --> 00:06:28.079
Think of it as an exclamation point.
00:06:28.160 --> 00:06:32.319
It's not the message itself, it's just something that says, hey, this is worth noticing.
00:06:32.560 --> 00:06:37.040
Without an adjuvant, some vaccines wouldn't stimulate a strong enough immune response.
00:06:37.199 --> 00:06:40.399
That could mean less protection or protection that doesn't last as long.
00:06:40.560 --> 00:06:49.279
In many cases, adding a small amount of aluminum allows scientists to use less of the vaccine antigen while producing a stronger, longer lasting immune response.
00:06:49.439 --> 00:06:55.040
So ironically, aluminum often helps reduce the overall amount of vaccine material that's needed.
00:06:55.279 --> 00:06:57.439
So why does aluminum sound scary?
00:06:57.680 --> 00:06:59.680
Well, let's address the obvious concern.
00:06:59.759 --> 00:07:02.800
You may be thinking, that's interesting, but isn't aluminum toxic?
00:07:02.959 --> 00:07:04.319
The answer is it can be.
00:07:04.480 --> 00:07:08.079
Just like many substances, this is where context becomes incredibly important.
00:07:08.240 --> 00:07:11.839
Aluminum is actually the third most abundant element in the Earth's crust.
00:07:12.000 --> 00:07:16.560
It's naturally present in soil, water, plants, and many of the foods that we eat.
00:07:16.720 --> 00:07:20.959
It's found in fruits, vegetables, tea, spices, infant formula.
00:07:21.120 --> 00:07:26.560
Even breast milk contains small amounts of aluminum because mothers are exposed to aluminum through their food and their environment.
00:07:26.800 --> 00:07:29.680
It doesn't mean that all exposure is automatically safe.
00:07:29.839 --> 00:07:34.560
It simply means aluminum isn't an unusual foreign substance that only exists in vaccines.
00:07:34.800 --> 00:07:36.879
It's something humans have always encountered.
00:07:37.120 --> 00:07:41.439
The real question isn't whether aluminum exists, the question is how much?
00:07:42.000 --> 00:07:45.040
Let's go back to a concept we talked about earlier, dosing.
00:07:45.199 --> 00:07:50.480
Our brains often think in categories, safe or dangerous, but biology usually thinks in doses.
00:07:50.639 -->
00:07:53.279
Imagine someone tells you they consume sodium today.
00:07:53.439 --> 00:07:54.399
Should you be worried?
00:07:54.560 --> 00:07:55.120
Probably not.
00:07:55.360 --> 00:07:59.920
Sodium is essential for nerve function, muscle contraction, and maintaining fluid balance.
00:08:00.079 --> 00:08:04.800
But if someone consumed an enormous amount all at once, that would be a very different situation.
00:08:05.040 --> 00:08:07.600
The same substance, different dose.
00:08:07.839 --> 00:08:10.079
The same principle applies to aluminum.
00:08:10.399 --> 00:08:13.279
The tiny amounts used in vaccines are measured carefully.
00:08:13.519 --> 00:08:21.680
Researchers have spent decades studying how much aluminum infants are exposed to from vaccines, food, water, medications, and the environment.
00:08:22.000 --> 00:08:29.680
One of the surprising findings is that babies receive far more aluminum through normal eating over the first several months of life than they do from vaccines.
00:08:29.920 --> 00:08:35.679
For example, infants naturally ingest aluminum from breast milk, formula, and later from solid foods.
00:08:36.000 --> 00:08:45.840
That surprises a lot of people, not because vaccines contain no aluminum, some do, but because many of us have never thought about how common aluminum exposure already is.
00:08:46.559 --> 00:08:49.679
So I'm going to go ahead and address an obvious objection.
00:08:49.840 --> 00:08:54.960
You might say, wait a minute, eating aluminum isn't the same thing as injecting it, and that's definitely true.
00:08:55.120 --> 00:08:56.720
The route of exposure matters.
00:08:56.879 --> 00:09:00.320
That's one of the four questions we said toxicologists always ask.
00:09:00.559 --> 00:09:04.480
Swallowed substances and injected substances are handled differently by the body.
00:09:04.720 --> 00:09:09.120
When aluminum is swallowed, only a very small percentage is absorbed through the digestive tract.
00:09:09.279 --> 00:09:11.120
Most of it simply passes through the body.
00:09:11.279 --> 00:09:16.320
When aluminum from a vaccine is injected into the muzzle, it doesn't instantly spread throughout the body.
00:09:16.480 --> 00:09:21.600
Instead, it remains at the injection site initially, where it helps stimulate the immune response.
00:09:21.759 --> 00:09:28.879
Over time, it is gradually dissolved, enters the bloodstream in small amounts, and is filtered by the kidneys before being excreted into the urine.
00:09:29.120 --> 00:09:32.320
Researchers have modeled this process extensively.
00:09:32.559 --> 00:09:40.480
Those models, along with laboratory studies, suggest that healthy infants' kidneys are capable of clearing those amounts well below levels known to cause toxicity.
00:09:40.639 --> 00:09:42.159
That's an important distinction.
00:09:42.399 --> 00:09:45.039
Scientists aren't simply assuming these doses are safe.
00:09:45.200 --> 00:09:52.480
They measured them, they modeled them, they compared them with known toxic levels, and they continue to monitor them over decades.
00:09:52.960 --> 00:09:56.080
Does that mean aluminum has never raised legitimate scientific questions?
00:09:56.320 --> 00:09:56.559
No.
00:09:56.799 --> 00:09:58.720
Scientists have absolutely studied it.
00:09:58.879 --> 00:10:06.879
Researchers have investigated whether aluminum containing vaccines could contribute to neurological diseases, autoimmune conditions, allergies, or developmental problems.
00:10:07.120 --> 00:10:09.120
Those are appropriate questions to ask.
00:10:09.279 --> 00:10:12.960
When an ingredient is used in millions of children, we should study it carefully.
00:10:13.120 --> 00:10:14.879
And that's exactly what researchers have done.
00:10:15.039 --> 00:10:18.240
I'll talk more about what those studies have found later in this episode.
00:10:18.480 --> 00:10:21.759
But before we leave aluminum, I want to leave you with one thought.
00:10:21.919 --> 00:10:26.080
The question isn't whether aluminum can be harmful under certain some circumstances, it can.
00:10:26.480 --> 00:10:29.279
The real scientific question is much narrower, narrower.
00:10:29.519 --> 00:10:32.480
Do the amounts used as vaccine adjuvants cause harm?
00:10:32.720 --> 00:10:34.639
That's a question that can actually be tested.
00:10:34.799 --> 00:10:38.799
And it's a very different question than simply asking whether aluminum exists in vaccines.
00:10:39.120 --> 00:10:43.360
Coming up next, we'll tackle perhaps the most famous vaccine ingredient of all, mercury.
00:10:43.919 --> 00:10:54.320
More specifically, why the mercury found in some vaccines wasn't the same kind of mercury that most people were warned about, and why that distinction became one of the biggest misunderstandings in the history of vaccine debates.
00:10:58.240 --> 00:11:05.200
If aluminum is the ingredient that raises the most questions today, mercury is probably the ingredient that changed the vaccine conversation forever.
00:11:05.440 --> 00:11:10.960
Even people who don't know much about vaccines often know one thing mercury is dangerous, and they're right.
00:11:11.120 --> 00:11:13.120
Certain forms of mercury are dangerous.
00:11:13.279 --> 00:11:17.600
In fact, mercury poisoning has caused devastating neurological disease throughout history.
00:11:17.679 --> 00:11:23.440
So if someone tells you vaccines contain mercury, your reaction might be, then why are we even having this conversation?
00:11:23.600 --> 00:11:26.559
The answer lies in one of the most important principles in chemistry.
00:11:26.720 --> 00:11:30.720
Sometimes two substances share a name but behave very differently.
00:11:30.960 --> 00:11:33.279
Many of us grew up hearing warnings about mercury.
00:11:33.600 --> 00:11:38.879
Pregnant women are advised to limit certain fish because large predatory fish can accumulate methylmercury.
00:11:39.039 --> 00:11:42.559
Communities have suffered from industrial mercury contamination.
00:11:42.799 -->
00:11:46.080
Mercury exposure at high levels can damage the developing brain.
00:11:46.240 --> 00:11:47.440
Those warnings are real.
00:11:47.600 --> 00:11:49.759
They're important and they should be taken seriously.
00:11:49.919 --> 00:11:55.840
So when parents first heard that vaccines contained a preservative related to mercury, it wasn't rational to be concerned.
00:11:56.000 --> 00:11:58.159
In fact, many scientists were concerned too.
00:11:58.320 --> 00:12:01.600
That's a part of the story that sometimes gets overlooked.
00:12:01.759 --> 00:12:05.039
Researchers didn't dismiss the question, they investigated it.
00:12:05.279 --> 00:12:08.799
The ingredient at the center of the controversy wasn't actually pure mercury.
00:12:09.120 --> 00:12:11.120
It was a preservative called dimerosol.
00:12:11.279 --> 00:12:14.879
Dimerosol had been used for decades in some multidose vaccine vials.
00:12:15.039 --> 00:12:16.320
Its job was straightforward.
00:12:16.480 --> 00:12:20.799
When a vial is designed to be used for multiple patients, it's punctured with the needle over and over again.
00:12:20.960 --> 00:12:25.440
Each puncture creates a small opportunity for bacteria or fungi to contaminate the vial.
00:12:25.600 --> 00:12:32.320
Before preservatives were routinely used, contaminated multidose medications occasionally cause devastating infections.
00:12:32.559 --> 00:12:35.360
Thimerosol dramatically reduced that risk.
00:12:35.600 --> 00:12:37.600
It helped keep vaccines sterile.
00:12:37.759 --> 00:12:40.480
In other words, it wasn't added because it helped the immune system.
00:12:40.639 --> 00:12:42.639
It wasn't added to make vaccines stronger.
00:12:42.799 --> 00:12:46.000
It was added to help prevent microbial contamination.
00:12:46.480 --> 00:12:48.960
But here's where the story becomes more nuanced.
00:12:49.200 --> 00:12:51.679
Thimerosol contains ethylmercury.
00:12:51.840 --> 00:12:57.519
The mercury most people had heard about from environmental disasters and contaminated fish is methylmercury.
00:12:57.679 --> 00:12:59.440
The names sound almost identical.
00:12:59.679 --> 00:13:03.440
Many people assume they behave the same way, but chemically they don't.
00:13:03.600 --> 00:13:06.480
Think about carbon monoxide and carbon dioxide.
00:13:06.639 --> 00:13:16.320
Both contain carbon, both contain oxygen, their names differ by only two letters, yet one is life-threatening in small amounts, the other is the gas we exhale every time we breathe.
00:13:16.559 --> 00:13:20.399
A small change in chemical structure can completely change how a substance behaves.
00:13:20.559 --> 00:13:22.159
The same principle applies here.
00:13:22.399 --> 00:13:25.039
Methylmercury stays in the body much longer.
00:13:25.200 --> 00:13:26.720
It accumulates over time.
00:13:26.879 --> 00:13:30.399
That's why repeated exposure through contaminated food can become dangerous.
00:13:30.559 --> 00:13:32.559
Ethylmercury behaves differently.
00:13:32.639 --> 00:13:38.960
It is broken down and eliminated much more quickly, does not appear to accumulate in the body the same way methylmercury does.
00:13:39.120 --> 00:13:43.519
That distinction became critically important as scientists began studying vaccines safely.
00:13:43.919 --> 00:13:44.720
But guess what?
00:13:44.879 --> 00:13:52.320
In today's day of vaccines, thimerosol is not even a question because it has been removed from most vaccines.
00:13:52.480 --> 00:13:58.159
This is one of my favorite parts of the story because it illustrates how public health decisions are often more nuanced than they appear.
00:13:58.399 --> 00:14:10.879
Around 1999, health officials reviewed the entire childhood vaccine schedule, not because children were getting sick from thimerosol, not because evidence had shown it was causing autism, but because the number of recommended vaccines had increased over time.
00:14:11.039 --> 00:14:18.639
When scientists added together the theoretical maximum amount of ethylmercury an infant could receive, they got every recommended vaccine containing thimerosol.
00:14:18.799 --> 00:14:24.879
That total approached, or in some cases exceeded, guidelines that had been developed for methylmercury, the different form of mercury.
00:14:25.279 --> 00:14:32.799
Remember, at that point, researchers didn't yet fully understand whether the two forms behaved differently enough for those guidelines to be applied separately.
00:14:32.960 --> 00:14:36.720
So health officials made what they described as a precautionary decision.
00:14:36.879 --> 00:14:41.679
If thymerosol wasn't essential in most routine childhood vaccines, why not remove it?
00:14:41.840 --> 00:14:46.159
It was an opportunity to reduce exposure while maintaining vaccine effectiveness.
00:14:46.399 --> 00:14:53.600
Beginning in 1999, manufacturers started removing thimerosol from nearly all routine childhood vaccinations in the United States.
00:14:53.840 --> 00:15:00.639
Today, with the exception of some multidose influenza vaccine formulations, routine childhood vaccines given in the U.S.
00:15:00.799 --> 00:15:05.919
either contain no thimerosol or only trace residual amounts from the manufacturing process.
00:15:06.159 --> 00:15:07.519
That's an important point.
00:15:07.919 --> 00:15:23.039
Many people still believe today that their child would receive thimerosol from vaccines, but the reality is, in my office, we no longer order even multidose flu vaccines, so there are no thimerosol-containing vaccines in our office.
00:15:24.080 --> 00:15:28.799
So once thymerosol was removed, many people expected autism diagnosis to decrease.
00:15:28.960 --> 00:15:33.440
It was a reasonable prediction if thymerosol had been a major cause, but that's not what happened.
00:15:33.600 --> 00:15:40.799
Over the following years, autism diagnoses continued to rise in the United States and in other countries that had removed thymerosol from childhood vaccines.
00:15:40.960 --> 00:15:47.840
At
the same time, researchers conducted numerous epidemiologic studies comparing children with different levels of thymerosol exposure.
00:15:48.159 --> 00:15:54.080
Overall, those studies did not find evidence that thimerosol exposure at the levels used in vaccines caused autism.
00:15:54.240 --> 00:15:56.879
Now it's important to say what that doesn't mean.
00:15:57.039 --> 00:16:02.000
It doesn't mean scientists stopped studying autism, it doesn't mean every question about autism has been answered.
00:16:02.159 --> 00:16:10.159
Autism remains an active area of research, with scientists investigating genetics, prenatal influences, early brain development, and many other factors.
00:16:10.399 --> 00:16:17.679
But the specific prediction that removing thimerosol from routine childhood vaccines would lead to a decline in autism was not borne out by the evidence.
00:16:18.000 --> 00:16:21.519
To me, one of the biggest lessons from thymerosol isn't actually about mercury.
00:16:21.759 --> 00:16:24.000
It's about how science responds to uncertainty.
00:16:24.240 --> 00:16:30.720
Scientists heard a concern, they investigated it, they made a precautionary policy change while continuing to study the issue.
00:16:30.879 --> 00:16:33.120
Then they kept collecting data after the change.
00:16:33.279 --> 00:16:39.600
Sometimes that process is interpreted as proof that something dangerous was being covered up, but another way to look at it is this.
00:16:39.840 --> 00:16:46.159
Scientist is willing to adapt when reasonable questions arise, even before the answer is known.
00:16:46.320 --> 00:16:49.200
That's not weakness, that's one of its strengths.
00:16:49.600 --> 00:16:59.360
Next, we're going to talk about another ingredient that often appears in memes of hidden vaccine toxins, formaldehyde, the same chemical many of us associated with preserving biological specimens.
00:16:59.519 --> 00:17:01.200
Why is it in vaccines at all?
00:17:01.279 --> 00:17:04.079
And does its presence mean what many people assume it means?
00:17:04.240 --> 00:17:06.079
Let's take a closer look.
00:17:09.759 --> 00:17:12.640
We've talked about aluminum, we talked about thimerosol and mercury.
00:17:12.880 --> 00:17:17.839
Now let's turn to another ingredient that often causes an immediate emotional reaction, formaldehyde.
00:17:18.000 --> 00:17:24.720
For many people, that word brings back memories of high school biology, a preserved frog, a special in a jar, a very distinctive smell.
00:17:24.960 --> 00:17:28.559
Maybe you heard that funeral homes use formaldehyde during embalming.
00:17:28.720 --> 00:17:34.079
So when parents discover that formaldehyde is used during vaccine manufacturing, the reaction is understandable.
00:17:34.240 --> 00:17:36.480
Why would I ever want that in my child's body?
00:17:36.640 --> 00:17:41.920
It's a fair question, but as we've seen throughout this episode, the name of a substance tells only part of the story.
00:17:42.160 --> 00:17:46.640
The amount, the purpose, the chemical context, those matter too.
00:17:46.960 --> 00:17:48.799
So why is formaldehyde used?
00:17:48.960 --> 00:17:55.359
Unlike aluminum, formaldehyde is not added to make vaccines work better, and unlike thimerosol, it isn't there to preserve the finished product.
00:17:55.519 --> 00:17:59.680
Instead, formaldehyde is primarily used during the manufacturing process.
00:17:59.839 --> 00:18:03.279
One of its jobs is to inactivate viruses or bacterial toxins.
00:18:03.359 --> 00:18:05.839
Think about diseases like diphtheria or tetanus.
00:18:06.079 --> 00:18:10.559
Symptoms aren't caused by the bacteria alone, they're caused by toxins the bacteria produce.
00:18:10.720 --> 00:18:18.799
Scientists can treat those toxins with formaldehyde, changing their structure just enough that they can no longer cause disease while still allowing the immune system to recognize them.
00:18:18.960 --> 00:18:23.119
It's a bit like taking the batteries out of a smoke detector before handing it to someone to study.
00:18:23.279 --> 00:18:28.240
It still looks the same, you can still learn from it, but it can no longer do what it was designed to do.
00:18:28.480 --> 00:18:34.799
After manufacturing, the vaccine undergoes multiple purification steps, and most of the formaldehyde is removed.
00:18:34.960 --> 00:18:37.519
Only tiny residual amounts remain.
00:18:38.000 --> 00:18:42.000
But here's another fact about formaldehyde that surprises almost everyone.
00:18:42.160 --> 00:18:44.640
Your body is making formaldehyde right now.
00:18:44.799 --> 00:18:46.079
Every minute, every day.
00:18:46.240 --> 00:18:49.440
Formaldehyde is a normal byproduct of human metabolism.
00:18:49.599 --> 00:18:54.480
Our cells produce it as they break down certain amino acids and other naturally occurring compounds.
00:18:54.640 --> 00:18:58.480
They also have enzymes specifically designed to break it down almost immediately.
00:18:58.720 --> 00:19:00.799
That doesn't mean formaldehyde can't be harmful.
00:19:00.960 --> 00:19:03.119
At high concentrations it absolutely can be.
00:19:03.440 --> 00:19:07.440
Workers exposed to large amounts over long periods require safety precautions.
00:19:07.680 --> 00:19:09.440
Again, context matters.
00:19:09.599 --> 00:19:17.200
The traced amounts that may remain in vaccines are small, far smaller than the amount naturally circulating in a healthy infant's bloodstream at any given moment.
00:19:17.359 --> 00:19:22.160
In other words, the formaldehyde in a vaccine doesn't introduce your child's body to a new chemical.
00:19:22.400 --> 00:19:28.400
It adds a very small amount of a substance their body is already producing, using, and breaking down continuously.
00:19:28.720 --> 00:19:32.000
Another concern that comes up frequently is preservatives in general.
00:19:32.160 --> 00:19:40.079
People often hear the word preservative and immediately think of processed foods, artificial additives, or something that's being used to
hide poor manufacturing practices.
00:19:40.319 --> 00:19:42.160
Preservatives exist for a simple reason.
00:19:42.319 --> 00:19:44.799
They help contem prevent contamination.
00:19:46.000 --> 00:19:52.480
Historically, before modern preservatives were used, contamination of an injectable medication caused outbreaks of severe illness and even death.
00:19:52.720 --> 00:19:55.119
Preservatives were there to reduce that risk.
00:19:55.359 --> 00:20:02.559
The great news is today, most childhood vaccines come in single dose, syringes, or vials which don't require preservatives at all.
00:20:02.720 --> 00:20:08.319
That's one reason routine childhood vaccines contain far fewer preservatives than many people assume.
00:20:13.200 --> 00:20:20.720
One thing I've learned is that people often hear the phrase, vaccines contain chemicals, and they conclude, therefore, vaccines are unnatural.
00:20:20.880 --> 00:20:22.640
But that's not really how chemistry works.
00:20:22.799 --> 00:20:24.720
Everything around us is made up of chemicals.
00:20:24.960 --> 00:20:26.799
Water and vitamin C are chemicals.
00:20:26.960 --> 00:20:29.039
The proteins that make up your muscles are chemicals.
00:20:29.200 --> 00:20:32.240
The DNA inside every one of your cells is made of chemicals.
00:20:32.400 --> 00:20:35.119
The question isn't whether something is a chemical, everything is.
00:20:35.279 --> 00:20:39.119
The better question is what chemical, how much, what does it do?
00:20:39.359 --> 00:20:40.640
How does the body handle it?
00:20:40.799 --> 00:20:45.039
Those are the questions that toxicologists ask, and they're the questions we should ask too.
00:20:45.279 --> 00:20:46.880
So where does the evidence leave us?
00:20:47.039 --> 00:20:56.319
After decades of research, surveillance, and the administrations of billions of vaccine doses around the world, scientists have accumulated a tremendous amount of information about vaccine ingredients.
00:20:56.480 --> 00:20:58.000
The evidence tells us several things.
00:20:58.160 --> 00:21:06.880
The ingredients used in vaccines each serve a specific purpose, whether that strengthen the immune response, preventing contamination, or helping produce the vaccine itself.
00:21:07.039 --> 00:21:10.640
The amounts are small, carefully regulated, and extensively studied.
00:21:10.799 --> 00:21:17.279
Researchers have specifically examined concerns surrounding aluminum-containing adjuvants and thymerosol containing vaccines.
00:21:17.440 --> 00:21:23.519
Though studies have not found evidence the amount used in vaccines caused the kinds of chronic health problems that many parents worry about.
00:21:23.759 --> 00:21:26.880
That doesn't mean scientists believe every question has been answered forever.
00:21:27.119 --> 00:21:28.640
Science rarely works that way.
00:21:28.880 --> 00:21:37.519
Researchers continue to monitor vaccine safety, improve manufacturing techniques, and develop new formulations that may require fewer ingredients
while maintaining protection.
00:21:37.759 --> 00:21:41.519
The willingness to keep asking questions isn't a sign that vaccines are unsafe.
00:21:41.680 --> 00:21:45.119
It's one of the reasons vaccines continue to become safer over time.
00:21:45.359 --> 00:21:47.039
So how do we find common ground?
00:21:47.200 --> 00:21:50.240
As we wrap up today, I want to return to something we said at the very beginning.
00:21:50.480 --> 00:21:54.079
Most parents aren't reading vaccine ingredient lists because they're looking for a fight.
00:21:54.240 --> 00:21:58.000
They're reading them because they're trying to protect their child, and that's a good instinct.
00:21:58.160 --> 00:22:00.079
I never want parents to stop asking questions.
00:22:00.240 --> 00:22:01.200
I hope they ask more.
00:22:01.440 --> 00:22:05.039
I hope they ask me, I hope they ask their pediatrician, I hope they ask scientists.
00:22:05.279 --> 00:22:07.440
Curiosity isn't the enemy of good medicine.
00:22:07.599 --> 00:22:09.039
It's one of its foundations.
00:22:09.200 --> 00:22:13.839
At the same time, I hope we can all recognize that some questions are more complicated than they first appear.
00:22:14.000 --> 00:22:23.839
Seeing a familiar chemical name on a vaccine label doesn't automatically tell us whether it's dangerous, just as seeing the word water doesn't tell us whether we're talking about a sip from a glass or a flood.
00:22:24.079 --> 00:22:26.319
The name is only a beginning of the conversation.
00:22:26.480 --> 00:22:31.519
The dose matters, the chemical form matters, and perhaps most importantly, the evidence matters.
00:22:31.759 --> 00:22:34.880
If there's one thing I hope you take away from today's episode, it's this.
00:22:35.119 --> 00:22:38.160
Ingredient lists don't tell stories, context does.
00:22:38.319 --> 00:22:43.359
And when we take the time to understand that context, I hope that your fear gives way to something better.
00:22:43.599 --> 00:22:48.799
Not blind trust, not unquestioning acceptance, but informed confidence.
00:22:49.359 --> 00:22:52.079
Thank you for joining me for another episode of Deep Dives.
00:22:52.240 --> 00:22:59.920
If today's conversation helped answer a question you had or maybe helped you think about it in a new way, I hope you'll share this episode with someone else who's trying to sort through the noise.
00:23:00.079 --> 00:23:08.000
Next time we'll take an even bigger step back and tackle one of the most common suspicions in the vaccine debate: big pharma, money, and conflicts of interest.
00:23:08.160 --> 00:23:09.680
How are the vaccines developed?
00:23:09.920 --> 00:23:10.799
Who profits?
00:23:10.960 --> 00:23:14.720
How should we think about financial incentives without letting them become the whole story?
00:23:14.960 --> 00:23:16.640
That's next time on Deep Dives.
00:23:16.799 --> 00:23:17.680
Until then, I'm Dr.
00:23:17.759 --> 00:23:18.559
Justin Smith.
00:23:18.720 --> 00:23:22.559
Stay curious, keep asking good questions, and take care of each other.