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Metals – Mercury

SOURCE

Mercury has been used for medications and is also found in many products that can cause toxicity to our bodies. Many know that the main consumption of mercury for humans is through seafood, but it is also found in vaccines to infants, dental amalgams, and some prescription medications.

MECHANISM OF ACTION

Mercury ions produce protein precipitation, enzyme inhibition, and corrosive action through their binding to sulfhydryl groups.

TOXICOKINETICS

Absorption of mercury into our bloodstream accounts for 90% of mercury binding to our red blood cells and 10% of mercury binding to our plasma cells. Humans that consume large amounts of mercury daily it was found that inorganic mercury was found in the whole blood (7%), plasma (22%), breast milk (39%), liver (16-40%) and urine (73%). Methylmercury is completely absorbed from our GI tract, distributed to the brain, liver, and kidney. Excretion is primarily in the feces.

 

SIGNS & SYMPTOMS

HISTORY

Mercury has been around for many centuries and used in scientific research. One example would be the use of mercury in thermometers. While these types of thermometers are no longer in use in the health care sector, China still produces several devices that contain mercury.

 

REFERENCES

Broussard, Larry, et al. “The Toxicology of Mercury.” LSU Health Sciences Center, 2021, watermark-silverchair-com.proxy.lib.ohio-state.edu/labmed33-0614.pdf.

Czaika, Ellen, et al. Mercury Science and Policy at MIT, 15 Jan. 2013, mercurypolicy.scripts.mit.edu/blog/?p=367.

National Research Council (US) Committee on the Toxicological Effects of Methylmercury. Toxicological Effects of Methylmercury. Washington (DC): National Academies Press (US); 2000. 2, CHEMISTRY, EXPOSURE, TOXICOKINETICS, AND TOXICODYNAMICS. Available from: https://www-ncbi-nlm-nih-gov.proxy.lib.ohio-state.edu/books/NBK225779/

Pesticides – Picaridin

BACKGROUND / HISTORY

As we approach the warmer summer months, bug spray is the perfect way to enjoy the outdoors by keeping the mosquitoes, flies, ticks, fleas, and triggers away. As an alternative to DEET, a newer form of bug spray contains the chemical picaridin, an insect and acarid repellent in the piperidine chemical family.

The history of picaridin goes back to when it was first developed in the 1980s by Bayer, and the EPA later registered it in 2001. It wasn’t until 2005 that it was first approved for use in the United States. The chemical name for picaridin is 1-piperidine carboxylic acid 2-(2-hydroxyethyl)-1-methylpropylester.

MECHANISM OF ACTION

How does picaridin work to repel insects? The insects detect the chemical sprayed on your skin or clothing through their olfactory sensing consisting of odorant receptors that need a common co-receptor and ionotropic receptors, leading to the insect’s inability to recognize its host’s cues. Researchers studied how mosquitoes respond to picaridin and found that the chemical stimulates sensory hairs on the mosquito’s antennae. This appears to prevent the mosquito from recognizing its host’s cues.

For humans, picaridin has limited dermal absorption and is metabolized via hydroxylation and glucuronidation. It is excreted in the urine.

 

TOXICOKINETICS

The toxicological profile of picaridin is classified as slightly toxic if ingested. The U.S. EPA considered picaridin to be slightly toxic for acute dermal and ocular exposure. Picaridin is not considered a skin irritant and is not a sensitizer, but it can cause slight to moderate eye irritation and practically non-toxic for inhalation exposure. Additionally, there is no evidence of genotoxicity, carcinogenicity, teratogenicity, reproductive toxicity, or neurotoxicity. Below you can find a chart from the National Pesticide Information Center of the different toxicology classifications.

SIGNS AND SYMPTOMS OF TOXICITY / TREATMENTS

  • Dermal irritation on human subjects following application of 20% picaridin aerosol, 20% picaridin lotion, or technical grade picaridin administered at the rate of 50 mg/cm.
  • Researchers noted a 39-year-old man developed an allergic reaction of contact dermatitis several hours after using repellent containing 10% picaridin.
  • There are no reported cases of major effect or death after the use of picaridin.

Treatment of dermal irritation caused by picaridin clean your skin with mild soap and lukewarm water to remove any irritants. Stop using picaridin and apply bland petroleum jelly like Vaseline to soothe the area. Try using anti-itch treatments such as calamine lotion or hydrocortisone cream (Cortisone-10).

 

SOURCES

  1. “Icaridin.” ChemSpider, www.chemspider.com/Chemical-Structure.111359.html.
  2. “Icaridin.” Uses, Interactions, Mechanism of Action | DrugBank Online, go.drugbank.com/drugs/DB14074
  3. “Picaridin.” National Pesticide Information Center, npic.orst.edu/factsheets/archive/Picaridintech.html.
  4. “Picaridin.” National Pesticide Information Center, npic.orst.edu/factsheets/PicaridinGen.html#:~:text=Picaridin%20can%20be%20used%20on,liquids%2C%20aerosols%2C%20or%20wipes.