A Beginner’s Guide to Chemicals

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Today with David McCullagh 12 min 2 speakers 8 chapters transcribed 8 days ago

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What does the word “chemical” actually mean to a scientist?

David McCullagh 0:00

The term chemical has in recent years received a lot of bad press, perhaps understandably according to our next guest, here with a beginner's guide to all things chemical is physicist Dr. Shane Bergen, Associate Professor of Public Engagement in Science at UCD. Shane, you're very welcome. Good morning. What does the word chemical mean to a scientist? Yeah. Uh everything.

Dr Shane Bergin 0:22

Right. It's just like all the matters of I've been coming on the show for ten years and I think this is perhaps the broadest topic I've ever spoken about. But uh as your introduction said, chemical is a term that has perhaps understandably a little bit of bad press 'cause we associate it with a certain type of things. But to a scientist, a chemical means literally everything, right? Be it the elements on a periodic table, the famous thing that we saw all up on the walls in our chemistry classrooms, through combinations of it. uh to make up molecules and compounds. You can have simple things like water, complex things like malachite, uh you could have a natural thing like a protein, synthetic thing like a paracetamol, benign stuff like cellulose, or deadly things like arsenic.

Dr Shane Bergin 1:05

So basically absolutely everything out there ever is a chemical. All things have chemical structure. Things that are not chemicals are more sort things like you know, maybe feelings or light or energy or force, some uh the stuff that basically doesn't have corporeal matter in it.

David McCullagh 1:23

Okay, so anything I can lift up or uh is is a chemical or has chemicals in it. So if you go into the shop uh you might see a food item being advertised as chemical free.

Dr Shane Bergin 1:35

What do you make of that?

Why do product labels claim “chemical‑free” and what does that really mean?

Dr Shane Bergin 1:36

Well of course, like I think the undergrad scientists in me would roll my eyes and kind of touch and say, such nonsense. But of course I I I understand what that means in reality, right? In the real world, chemical free means natural or hasn't a huge amount of additives in it. It can also be the case in for synthetics and uh cosmetics and this idea that the closer to the the kind of more natural uh stuff that's out there, the better it might be for you. So if you take a packet of something you pick up in the supermarket and you turn it over, you'd see a bamboozling and legally mandated list and I'd have to confess I don't know what most of them are. So what

David McCullagh 2:15

chance do I have?

Dr Shane Bergin 2:16

Yeah. I'm sure perhaps better than me, but like you might want natural apple juice and then you turn it over and say, Oh, there's sodium benzoate in it. What the hell is that? But really what it's there to do is to keep the apple juice from spoiling. Anyone who's making apple juice at home at the moment, this time of year, will tell you it won't last more than a few days. Ditto for milk, you might see um that it's fortified. You're wondering, what does that mean? It might just have vitamin D in it. So there's a lot of governance that goes on uh in terms of those those lists and I suppose like even scientists don't understand all the terms. So we have to have some degree of trust that somebody somewhere along the food chain has our best interests at heart and not necessarily the bottom line for a shareholder at heart.

Dr Shane Bergin 3:00

And that's a fine balance. Not that's

David McCullagh 3:01

Indeed. Uh so I mean you mentioned natural. Is natural a uh a useful way of distinguishing between good chemicals and bad chemicals?

How are the millions of known chemicals classified into groups like acids, bases and organics?

Dr Shane Bergin 3:08

Yes and no. Yes, because natural tends to mean we have over thousands of years evolved to live in equilibrium with it, right? You know, uh so we can assume that most natural things are probably less harmful. However, th nature is n does not have like a safety department, right? So there are things like botulinium, right? Which is a naturally occurring um chemical that w is a nerve agent, like kill you. Um uh, ditto for arsenic, uh, an exposure to a small amount of it, or cyanide uh for that matter. Uh all of these things are completely natural. Um so they don't natural doesn't necessarily mean good and and the converse is synthetic things like uh virtually every paracetamol or every uh pharmaceutical is is is completely man made or human made.