solidsurfacealliance.org Blog

In the past few years of researching the issue of radiation in granite countertops, many things were found to have multiple recomendations. One issue that has been consistent is the allowed doses for pregnant women, even the skeptics prefer not to take a chance with a developing fetus.

Basically, the developing fetus is far more likely to suffer damage during the first few months of pregnancy. So if a health issue arises with the mother, the dose from radioactive medical procedures must be know, then the risk/benefit of the procedure discussed with the patient, and a decision made on whether or not to have the procedure.

Here is a link to some info on Fetal Doses for common medical procedures.

It is of interest to this discussion in two manners, to show the risk of radiation from any source to developing babies, and to show that granite countertops can provide the same dosage given enough exposure time.

As an example, we have in our shop this week a slab of Four Seasons granite that was found during a survey of one of our suppliers. It measures 12.5 mR/hr for Alpha, Beta, and Gamma. Blocking the Alpha resulted 10.5 mR/hr. Blocking both Alpha and Beta resulted in 3.5 mR, Gamma radiation only.

To put this into perspective, an abdomen X ray from the Fetus dose chart showed 240 mR dose, so keeping it conservative by using the Gamma results of the Four Seasons granite, means that 68 hours of standing in front of or sitting at this counter would provide the same radiation exposure. Two hours per day, 34 days. Of course even being in the kitchen within five or six feet will provide a dose as well, less so because of distance, but some radiation will hit.

We recently found a case of a hot spot in Bordeaux, right at the most popular place in the kitchen for sitting. Luckily, the lady’s pregnant neice had not used the penninsula, just the kitchen, so the dose was much lower.

A chest X ray according to the Fetal Dose chart, provides less than 10 mR per Xray. The Health Physics Society claims that an average dose to an adult is around 5 mR per Xray. Using the 3.5 Gamma only from the Four seasons, sitting there for one hour and 25 minutes gives a fetus 5 mR radiation dose.

So like a medical procedure, a pregnant woman needs to know that radiation is coming from that granite countertop, and decide for herself if the risk is acceptable or necessary.

Once found, shipments of simular granite were stopped by our supplier within minutes untill testing equipment was sent to Brazil. Also, current orders for that material were canceled till the existing slabs were checked. Once a meter was delivered to Brazil, they found that 3 out of 8 bundles would be acceptable for radiation content and quality. Once other importers start measuring radiation when purchasing granite, expect prices to rise on the low level slabs and prices to drop on the high radiation level slabs. Then it will become even more important for a homeowner to see the slabs tested before their very eyes as a cheaper high radiation level slab could be substituted for a more costlier low radiation level slab.