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Unexpected Lessons in Dermatotoxicology: De minimis Magnesium⁺⁺

By: Hongbo Zhai, MD, and Howard I. Maibach, MD, University of California

Posted: April 30, 2010, from the May 2010 issue of Cosmetics & Toiletries.

Traditional dermatotoxicologic investigations focus on dermatitis as well as potential systemic effects¹ but rarely have they focused on trace ions. The following lesson opens new avenues of thought and investigation for intimate care product developers, since the trace ions described may dramatically impact the end product.

Toxic Shock Syndrome
Toxic shock syndrome (TSS), a rare but potentially fatal illness, is caused by toxins produced by bacteria and is characterized by the sudden onset of fever, chills, vomiting, diarrhea, muscle aches and rash. It can rapidly progress to severe and intractable hypotension and multisystem dysfunction. Desquamation, particularly on the palms and soles, can occur 1–2 weeks after the onset of the illness.² TSS was first reported in children of both sexes in 1978 and subsequently brought to the public’s attention when it became associated with menstruating women using tampons.²

In 1980, an outbreak of TSS occurred involving mostly young women who had been using one brand of superabsorbent tampons. How the tampons caused TSS is partially understood; it has been hypothesized² that when a superabsorbent tampon is left in place for a prolonged period of time, the tampon becomes a bacteria breeding ground. Others have suggested that the tampon’s superabsorbent fibers can abrade the vagina surface, making it possible for bacteria or their toxins to enter the bloodstream. However, the tampon brand associated with the original TSS epidemic in the 1980s was voluntarily taken off the market by the manufacturer and afterwards, the number of TSS cases declined dramatically.²

Most TSS cases are caused by the Staphylococcus aureus bacteria but can also result from toxins produced by streptococcus bacteria.³ While TSS often occurs in menstruating women, it can also affect men, children and postmenopausal women. In fact, one third of all cases of TSS occur in men. Other risk factors for TSS include skin wounds and surgery.

Magnesium Ions
In 1985, Mills et al.³ reported that the in vitro production of toxic shock syndrome toxin-1 (TSST-1) by Staphylococcus aureus is influenced by the concentration of magnesium ions (Mg⁺⁺) in the culture medium. The complete removal of Mg⁺⁺ from the culture medium was found to severely restrict the multiplication of the test staphylococci. On the other hand, with the addition of a small amount of Mg⁺⁺, toxin production increased; yet with excess amounts of Mg⁺⁺, toxin production was diminished.^2-4 Figure 1 shows the effect of the concentration of magnesium ion on the concentration of TSST-1. The tampon fibers caused the epidemic TSS bound Mg⁺⁺ and therefore strikingly increased toxin production.⁵