Hot News‎ > ‎

Better Standards?

posted Mar 21, 2015, 8:28 AM by Rachel Aronoff   [ updated Mar 23, 2015, 12:10 PM ]
Laws are being proposed to update the Toxic Substances Control Act (which, interestingly, was actually started as the Food Drug and Cosmetic Act of 1938, because of rampant toxicity of early methods to remove unwanted hair). 
However, whatever the politicians in congress decide, with 1000s of untested compounds, it is a long shot that even the next generation will benefit from possibly (depending on the outcome of democracy/industry) improved risk assessments…
Our personal choices thus remain extremely important!
In the meantime, what is considered safe - and what needs emergency responses - is largely based upon 'macro' scale effects, at the limit between cell genomic integrity and outright symptoms. 
For instance, see the case of benzene exposure which has carcinogenic potential after being metabolized:
    • 700 to 3,000 ppm: Drowsiness, dizziness, headaches, tremors, confusion, unconsciousness, abnormally rapid heart rate (tachycardia), and irritation of the moist linings (mucous membranes of the respiratory tract).
    • 3,000 ppm and above: Slow and shallow breathing; a deeper level of unconsciousness, due to narcotic-like action on the CNS; and with prolonged exposures, seizures, paralysis, abnormal (potentially fatal) heart rhythms (cardiac arrhythmia), and cessation of breathing (apnea).
    • 20,000 ppm for 5 minutes: Cessation of breathing (apnea) due to accumulation of fluid in the lungs (pulmonary edema).
    • If benzene is ingested and vomited, inhalation of benzene-containing vomitus into the lungs (aspiration) may cause potentially fatal lung damage.
    • Mild to moderate: Irritation, redness (erythema), and burning sensation.
    • Severe: Fluid accumulation (edema), blistering (vesication), and inflammation (dermatitis).
    • Absorption through the skin is slow, but it may contribute to whole-body (systemic) toxicity.
    • See Inhalation Exposure
As always, the dose makes the poison, and these symptoms mean emergency clean up of such compounds requires complete respiratory and chemical protective gear.  Still, on the other hand, ingredients of concern in personal care products, like benzene derivatives, even if used in low doses, are directly applied to the skin and may have the full day to be gradually absorbed past epidermal layers and perhaps even into cell nuclei  As shown by controlled experiments and In spite of what some* might want to believe, the unconsidered 'time' factor has already been invoked, as reviewed previously, in terms of risk of exposure to hormone-mimetic substances, which don't allow straightforward dose/response conclusions as to expected effects.  Some of these substances (like BPA) also can be viewed as affecting genomic integrity (by changing gene expression or even, based on their chemical structures and predicted metabolites, by directly interacting with nucleic acids). 

The reason why the 'bad luck' aspect of stem cell level genomic hits is so important could simply have to do with random, low frequency events - even if effects from individual choice/exposures, on top of the inherent error of the DNA replication system due to base isomerisation, which can always be argued as essential for evolution, cannot be ruled out.  To retain surviving cells with just the wrong genetic defect can be worse than the actual death of exposed cells, as stated previously.  Additionally, outright toxicity of some sort vs. perturbations in genomic integrity have such different time scales that the latter is rarely assessed - although examples are gradually getting out there (again, here is a benzene example, with three tested assays). 
AGiR! hopes to encourage more such efforts. 
In addition, amazing examples of basically blown apart chromosomes in cancer, can be taken to imply some cataclysmic event…  (high exposure to something that penetrates to cell nuclei?) 
Unfortunately, funding sources can induce significant bias, a continuing problem, thus weakening not only the strength of results, but public perception of scientific endeavors.

*Expect more in this regard, in an upcoming blog post!
Hoping for some more feedback...
Take care!