Californium

Warning: anything and everything made up of any combination of the any of the following elements is known to the State of California to cause cancer:

H - Hydrogen
He - Helium
Li - Lithium
Be - Beryllium
B - Boron
C - Carbon
N - Nitrogen
O - Oxygen
F - Fluorine
Ne - Neon
Na - Sodium
Mg - Magnesium
Al - Aluminum, Aluminium
Si - Silicon
P - Phosphorus
S - Sulfur
Cl - Chlorine
Ar - Argon
K - Potassium
Ca - Calcium
Sc - Scandium
Ti - Titanium
V - Vanadium
Cr - Chromium
Mn - Manganese
Fe - Iron
Co - Cobalt
Ni - Nickel
Cu - Copper
Zn - Zinc
Ga - Gallium
Ge - Germanium
As - Arsenic
Se - Selenium
Br - Bromine
Kr - Krypton
Rb - Rubidium
Sr - Strontium
Y - Yttrium
Zr - Zirconium
Nb - Niobium
Mo - Molybdenum
Tc - Technetium
Ru - Ruthenium
Rh - Rhodium
Pd - Palladium
Ag - Silver
Cd - Cadmium
In - Indium
Sn - Tin
Sb - Antimony
Te - Tellurium
I - Iodine
Xe - Xenon
Cs - Cesium
Ba - Barium
La - Lanthanum
Ce - Cerium
Pr - Praseodymium
Nd - Neodymium
Pm - Promethium
Sm - Samarium
Eu - Europium
Gd - Gadolinium
Tb - Terbium
Dy - Dysprosium
Ho - Holmium
Er - Erbium
Tm - Thulium
Yb - Ytterbium
Lu - Lutetium
Hf - Hafnium
Ta - Tantalum
W - Tungsten
Re - Rhenium
Os - Osmium
Ir - Iridium
Pt - Platinum
Au - Gold
Hg - Mercury
Tl - Thallium
Pb - Lead
Bi - Bismuth
Po - Polonium
At - Astatine
Rn - Radon
Fr - Francium
Ra - Radium
Ac - Actinium
Th - Thorium
Pa - Protactinium
U - Uranium
Np - Neptunium
Pu - Plutonium
Am - Americium
Cm - Curium
Bk - Berkelium
Cf - Californium
Es - Einsteinium
Fm - Fermium
Md - Mendelevium
No - Nobelium
Lr - Lawrencium
Rf - Rutherfordium
Db - Dubnium
Sg - Seaborgium
Bh - Bohrium
Hs - Hassium
Mt - Meitnerium
Ds - Darmstadtium
Rg - Roentgenium
Cn - Copernicium
Nh - Nihonium
Fl - Flerovium
Mc - Moscovium
Lv - Livermorium
Ts - Tennessine
Og - Oganesson

What’s that?
Oh, yes.
Even Californium.