Toxicology

What is Toxicology?

"Toxicology is a field of science that helps us understand the harmful effects that chemicals, substances, or situations, can have on people, animals, and the environment. Some refer to toxicology as the “Science of Safety” because as a field it has evolved from a science focused on studying poisons and adverse effects of chemical exposures, to a science devoted to studying safety. Toxicology uses the power of science to predict what, and how chemicals may cause harm and then shares that information to protect public health."

-From the National Institute for Environmental Health Sciences (NIEHS)

Learn more about toxicology from NIEHS

Toxicology Resources

These are the ones you should keep up front.

Agency for Toxic Substances and Disease Registry (ATSDR)

International Agency on the Research of Cancer (IARC)

IARC Website: https://www.iarc.fr/

Interested in knowing what is carcinogenic? This agency summarizes levels of evidence into five groups, ranging from "probably not carcinogenic" (group 4) to "carcinogenic to humans" (group 1).






Toxicology Impacts (Why it Matters)

Pollution impacts on health

Read:

Erickson, B.E. (2019). Linking pollution and infectious disease. Chemical and Engineering News, American Chemical Society, March 18, 2019 (via American Chemical Society)


Secret Life of Fat

The Secret Life of Fat, with Michele La Merrill. 8 min Podcast

Great for understanding how fat can interact with persistent organic pollutants (POPs) to be a target for toxicity

Gardening & Contaminated Soil

R Kessler, Urban Gardening: Managing the Risks of Contaminated Soil, 2013.

Great for the gardeners out there especially when “OK, we’re contaminated, how do we fix it?”


Mixed Metal Exposure in Kids

Mixed Metals Exposures in Children, with Robert O. Wright. 7 min Podcast

Great for understanding that heavy metals can work in synergy to affect health – and unless you’re measuring them together in a person, you’ll have no idea that the person is risk-exposed

How does it work? More about mechanisms

Toxicology and Dose Response

A Deeper Look: Dose and Poison

Watch:

  • Toxicology & Dose Response (16 min video)

Read:

  • Frumkin 3rd edition (2016); Chapter 06 - Toxicology, starting on page 123 – Great for a solid understanding of toxicology principles.

Optional Reading:

  • Frumkin Chapter 08 Exposure Science, Industrial Hygiene, and Exposure Assessment starting on p181 – a lot of this has been on the CPH exams I’ve seen. Reinforces toxicology principles needed when we discuss Risk Assessment.

  • Grandjean, P. (2016). Paracelsus revisited: the dose concept in a complex world. Basic & clinical pharmacology & toxicology, 119(2), 126-132. (via Google Scholar)

Watch List

Keep an eye out for these general classes of chemicals.

Persistent Organic Pollutants

Forever chemicals. Highly soluble in fats.

Includes polychlorinated biphenyls (PCBs), organochlorine pesticides (like DDT), PBDEs, and dioxins. Look for benzene ring structures.

Learn more about POPs via EPA

See the "Dirty Dozen" list identified by the Stockholm Convention (2001)


Per- and polyfluoroalkyl substances (PFAS)

These also bioaccumulate. One of the earliest was Scotch Guard, which we sprayed on everything. Also, think Teflon.

  • PFAS found in breast milk.

Awad R, Zhou Y, Nyberg E, Namazkar S, Wu Y, Xiao Q, Yaije S, Zhu ZL, Bergman Å, Benskin JP. Emerging per-and polyfluoroalkyl substances (PFAS) in human milk from Sweden and China. Environmental Science: Processes & Impacts. 2020. DOI: 10.1039/d0em00077a Read PDF via RSC.org

  • Review:

Chang ET, Adami HO, Boffetta P, Cole P, Starr TB, Mandel JS. A critical review of perfluorooctanoate and perfluorooctanesulfonate exposure and cancer risk in humans. Crit Rev Toxicol. 2014 May;44 Suppl 1:1-81. doi: 10.3109/10408444.2014.905767. Epub 2014 May 5. PMID: 24793953.

  • 2022 ray of light: New way to degrade PFAS!

Trang, B., Li, Y., Xue, X. S., Ateia, M., Houk, K. N., & Dichtel, W. R. (2022). Low-temperature mineralization of perfluorocarboxylic acids. Science, 377(6608), 839-845.

Learn about PFAS (via ATSDR)


Image via SE Alaska Conservation Council

Polycyclic Aromatic Hydrocarbons (PAHs)

Carcinogenic combustion byproducts. They also have a benzene ring structure, so think soluble in fats.

Released via Deepwater Horizon Oil spill in 2010.

Source: Berenshtein I, Paris CB, Perlin N, Alloy MM, Joye SB, Murawski S. Invisible oil beyond the Deepwater Horizon satellite footprint. Science advances. 2020 Feb 1;6(7):eaaw8863.

Learn about PAH (via ATSDR)

Polybrominated Diphenyl Ethers (PBDEs)

Think flame retardants. There are more than 200 varieties. They are considered POPs and have ring structures. Since they bioaccumulate, you can expect to find them in tissue.

Sadly, they have already been found in Inuit diets.

Cite: Schæbel LK, Bonefeld-Jørgensen EC, Vestergaard H, Andersen S. The influence of persistent organic pollutants in the traditional Inuit diet on markers of inflammation. PLOS One. 2017 May 19;12(5): e0177781.
Image of bioaccumulation via Wikimedia. Look for increasing concentrations as it makes its way up the food chain.

Persistent Toxic Substances

Similar to POPs, but different:

  • Like POPs, they can be transported long distances

  • Like POPs, they can bioaccumulate in organisms and enter the food chain

  • Not "POPs" – not originally listed in the Stockholm Convention

  • Typically, PTS include natural and manmade chemicals. They typically don’t have to include phenolic ring structures like the POPs above (organic = ring structure).

  • Could include: mercury, cadmium, lead, polybrominated diphenyl ethers (PBDE – flame retardants), others


Source: Wong MH, Armour MA, Naidu R, Man M. Persistent toxic substances: sources, fates and effects. Rev Environ Health. 2012;27(4):207-13. doi: 10.1515/reveh-2012-0040. PMID: 23079509.

Heavy Metals

The Oregonian did a feature on heavy metals in Portland. Explore the site. And the original story. Amazingly, they were able to measure via moss.


Citation: Zarkhin, F. New toxic heavy metal issue for Portland: Cobalt. The Oregonian/Oregon Live. Posted June 8, 2016 [Updated April 22, 2019]. https://www.oregonlive.com/environment/2016/06/new_toxic_heavy_metal_issue_fo.html

Lead

Read: Lead FAQ via ATSDR


Or the longer ATSDR Lead Profile

Know lead. Super important.

Image via DC water

Cadmium

Read: Cadmium FAQ via ATSDR


Or the longer ATSDR Cadmium ProfileUsage trends of cadmium in picture via OSHA


Nickel

Read: Nickel FAQ via ATSDR


Or the longer ATSDR Nickel ProfileImage above via NIOSH's nickel page


What I'm most excited about in environmental toxicology

Microbiome as a pollutant metabolizer

Claus, S.P., Guillou, H., Ellero-Simatos, S. (2016). The gut microbiota: a major player in the toxicity of environmental pollutants? Nature Biofilms and Microbiomes, 2, 16003. doi:10.1038/npjbiofilms.2016.3

NEW SCIENCE - Fascinating Reading! Full text via Nature

What is the microbiome?

The microbiome describes all of the bacteria that live in our bodies. They influence our decisions, what we eat, and how our bodies process medicine. It sounds like science fiction, but it's new science that is having big implications.


And remember that whole fungi kingdom? Well, it turns out that they're looking to be involved, too. Keep your eye out for mycobiome research!


Student Recommended Resources

This Podcast Will Kill You

Toxicology Podcasts from This Podcast Will Kill You



Inspired Toxicology Infographics

Compound Interest

A high school chemistry teacher in the U.K. amazes me time and time again with his colorful infographics describing important principles in toxicology and chemistry.

Visit Compound Interest

Play

  • After toxicology week, do you remember how that metal is measured? Take this quick 4 question mix and match about how each metal exposure is measured - https://quizlet.com/join/4vwZqQyEV (Play using the "match" function)