FEATURES BIOCHEMISTRY
What we don’t see in the
and
appealing colours Noelle breaks down the colours all around us, exposing the deadly toxicity lurking underneath the surface of some... Lee SFC1 Pigments have added so much colour to our lives, influenced by the consumerist society to manufacture thousands of artificial colours. Yet what if someone told you that these pigments could be a deadly weapon? From bright red to platinum white to extravagant green, these pigments are considered three of the most poisonous pigments in the history of mankind.
(and orange and yellow) Cadmium is the 48th element in the periodic table, a scarce transition metal discovered in the 19th century, and an important pigment to artists which could produce bright reds, oranges and yellows in miniscule amounts. Featured in world-renowned artworks such as "The Scream" by Edward Munch and "Sunflowers" by Vincent van Gogh, it angered artists when the ban of cadmium paint was proposed in 2015 by the European Chemical Agency (ECHA) after Swedish officials suggested that artists polluted the water supply during cadmium paint disposal. As you wonder why cadmium paint is still widely used at present, cadmium only poses a dangerous health risk once inhaled, which is why dissolved lowconcentration cadmium paint is not the - biggest threat. In fact, we should be more concerned about the paint manufacturers who produce the paint from dry cadmium powder, which is why they can only produce paint a few days per year due to the hazards associated with inhaling cadmium. Cadmium, when inhaled, could bring detrimental or fatal effects to the human body. After entering the bloodstream, cadmium is widely distributed in the body, and mostly accumulates in the liver and kidney. 31
Does the body ever contribute anything into combatting cadmium toxication? In fact, it does. Metallothionein (MT) is a small cysteine-rich protein that is especially abundant in the liver and kidney and plays important roles in protection against heavy metal toxicity, DNA damage and oxidative stress. Due to MT’s high affinity for heavy metals, cadmium binds easily to it to form inert CdMT complexes, which are degraded by lysosomes to be excreted through urination. However, at higher levels of cadmium (Cd), Cd ions exceed the buffering capacity of intracellular MTs so are unable to stop cadmium from roaming around the body and destroying cells. Although we cannot blame our body for not producing enough metallothionein, cadmium undoubtedly brings irreversible damage to almost every system in the human body. What makes this heavy metal a deadly "wild card"? Instead of targeting certain organs, cadmium attacks vital substances and cell components in the body, such as DNA repair proteins and the mitochondria. Cadmium inactivates DNA-repair proteins, and those with zinc-binding domains (ZBD) are especially sensitive targets. Cadmium ions (Cd2+) like to displace ions of similar charge, such as Zn2+ ions, and by doing so, they inhibit ATP synthase and helicase activities - these are enzymes crucial to respiration and DNA replication respectively.
Inactivation of Zinc Binding Domains or Zinc Fingers. Downloaded by Virginia Commonwealth University on 20/03/2017 23:32:15.
Possible outcomes are changes in chromosome structure or number (chromosomal aberrations) and breaking of DNA strands, hindering cell growth and causing apoptosis (cell death) or inactivating tumour suppressor genes. We all know what follows: cancer. Directly or indirectly, DNA-protein inhibition increases the cadmium carcinogenicity, inducing lung, prostate and renal cancer.
