Toxicity in some granite counter tops

Unbelievable!! It never ends. Well, we just got granite countertops in our kitchen and their beautiful. -I will enjoy my kitchen whether it kills me or not!

Julie

CP418,

I appreciate the link to our page on the toxic heavy metal aspects of granite countertops.   And yes, we do have a vested interest in informing people about the issues of competing countertop materials, however if we didn't do this, the problems would be completely unknown.  The toxic heavy metal issues have been known  to the stone industry for decades, as all granites that are sold commercially (for commercial work like bank lobbies, courthouse and public buildings, and exteriors of buildings) are tested for heavy metal content.    Why, I don't know because people aren't having a lot of skin contact with stone used for those purposes.  But I am glad someone is considering any risks.

But, a granite countertop, that is way different.  People prepare food on them, many stone websites will mention rolling dough or cooling cookies on granite tops. People use them for cutting boards, there are even videos of stone fabricators cooking steaks on granite slabs then eating the steaks!

Most of these heavy metals are water soluble, some are fat soluble, others are in an oxidation state that is safe UNTIL a slightly acidic ( cleaning solution,tomato juice, soda, or even coffee) or slightly alkaline food or liquid comes in contact.   One expert said he wasn't sure if he wanted a cleaning product that would remove the heavy metal present on the surface or if he would prefer a cleaning solution that didn't dissolve the heavy metals.

The testing and research is just now beginning, no one has looked into this issue except for the commercial stone tests that have been done for decades, but the countertop granites are untested at this point in time.  The stone industry lobby association, the MIA, knows of the problems but is doing nothing to find out the truth.  Like the radon/radiation in granite issue, they are likely to fight this tooth and nail to prevent the facts from coming out.

 One common misconception is that members of the Solid Surface Alliance fabricate and sell only solid surface.  Not true, most are like our shop, which sells granite and every other type of product.   What makes us different is that since we are multi material shops, we can afford to find out the facts and deal honestly with our customers.  We feel that consumers have the right to know and make their own choices of whether to take the risk or not.

A few weeks ago, one of our members (an industrial hygienist that has been assisting us on the radon/radiation issues) took a sample of a countertop into a scientific lab supply company and did an XRF reading.   The machine reported 10,260 ppm of Thallium, that would be over one percent!   Heavy metals have different allowed content numbers depending on their toxicity, lead in childrens toys has to be less than 600 ppm and most other heavy metals must be less than 100 ppm.  So this granite, a Bordeaux countertop that was removed after it was found to be highly radioactive, is over 1,000 times over the safe limit for a toy. 

 Here is a link to more info including the data spreadsheet from the XRF test.

http://forum.solidsurfacealliance.org/viewtopic.php?f=7&t=177

 What is even more troubling is the skin contact limit for Thallium, one tenth of a  milligram per square meter of skin.  To put this in perspective a postage stamp without the backing paper would weigh around 57 milligrams, so the maxium allowed skin contact of Thallium per 8 hour day for a worker is 570 times less than the weight of a postage stamp!    Keep in mind this is for an industrial worker, who knows of the risk, accepts the risk as part of his employement, and whose exposure and health is  carefully monitored.  Most industrial limits are far, far, higher than what is allowed for the general public.

Another way to look at this is to assume that the Thallium is spread evenly throughout the granite contertop (it won't be but we have to simplify to get anywhere).   A lot of granites will weigh around 18 pounds per square foot, and if one percent is Thallium, there is .18 pounds of Thallium present per square foot of stone. That would give you 81,467 milligrams per square foot of stone, then assume 1,000 th of the Thallium is at the suface where it can be in contact with food or human skin, and you have a major problem,  81.6 milligrams of Thallium spread over the surface of the stone.

From our research on radiation in stone, we know that some stones will have a large quanity of uranium (another heavy metal that is extremely toxic) uniformly mixed into the entire slab, other stones will have less uranium but it will be concentrated in veins, pockets,  or specks..  Heavy metals will concentrate in the same manner as uranium, either uniformly mixed or in hot sections, so there is really no way to be sure how much heavy metal is exposed on the surface.

Here is what Wikipedia had to say about the toxicity of Thallium:

Thallium is highly toxic and is used in rat posions and insecticides, but its use has been cut back or eliminated in many countries. Because of its use for murder, thallium has gained the nicknames "The Poisoner's Poison" and "Inheritance Powder" (alongside arsenic).

(It has a dull silvery look, which is common in lots of granites, small specks up to pencil eraser size in some cases)

 In the presence of water, thallium hydroxide is formed. Thallium and its compounds are extremely toxic, and should be handled with great care. Contact with skin is dangerous, and adequate ventilation should be provided when melting this metal. Thallium(I) compounds have a high aqueous solubility and are readily absorbed through the skin. Exposure to them should not exceed 0.1 mg per m² of skin in an 8-hour time-weighted average (40-hour work week). Thallium is a suspected human carcinogen.