Fluoride – it’s more than just toothpaste!

©2011 Inorganic Ventures, Inc.

Fluoride.  It’s good for your teeth and bones!  It’s a communist mind control plot!  It prevents cavities!  It’s highly toxic!  These arguments have raged for many, many years over the practice of adding fluoride to drinking water, and will likely rage for many years to come.  Fluoride is the (-1) oxidation state of the element fluorine, and if you don’t remember about oxidation states, see the previous article on chromium (VI).  It does indeed help prevent cavities by forming an acid resistant coating on your teeth which is less likely to break down in the presence of the acids formed by plaque causing bacteria in your mouth.  And it can be toxic in high enough doses; but just like with most things, it’s the dose that makes the poison.  A little can be good, too much can be bad. The effects of fluoride on tooth decay were first discovered in the late 1800’s as scientists began researching the cause of the tooth streaking and mottling people get when exposed to high concentrations of naturally occurring fluoride.   It was also noticed that in these same areas, the incidence of tooth decay was a great deal lower than the average.  It didn’t take long before someone put two and two together, and by about 1945 municipalities started adding fluoride to the drinking water in an attempt to prevent tooth decay.  By the early 1950’s, studies had been conducted that showed significant reduction in the number of cavities in those areas where fluoride was being added.  And to this day, not a single one of those areas has been over-run by communists!  Public health and wellness organizations, such as the American Dental Association and the Centers for Disease Control, still recommend the addition of a small amount of fluoride to drinking water in those areas where it is not naturally occurring.  Fluoride has been in the news quite a bit recently in the United States because changes as to the recommendations on the amount of fluoride to be added to drinking water have been proposed.  Currently, the U.S. Department of Health and Human Services recommended range is 0.7 mg/L to 1.2 mg/L, but they are proposing to change it to just 0.7 mg/L, making it the same as the current recommendation from the Centers for Disease Control.  The EPA is also reviewing the Primary Maximum Contaminant Level (MCL) for fluoride, which is currently 4.0 mg/L, and the Secondary Maximum Contaminant Level (SMCL), which is 2.0 mg/L; California has its own primary MCL of 2.0 mg/L.  There is some fluoride in almost all groundwater, but generally it is below the current MCL’s and SMCL’s.  However, there are many places in the U.S. where the fluoride levels may be at or slightly exceed 0.7 mg/L.  If this level were to become an enforceable standard, then many water systems would have to implement fluoride removal treatment, which can be quite costly.

A little hexavalent chromium information.

©2011 Inorganic Ventures, Inc.

On December 20, the Environmental Working Group (EWG) released a report on a “study” they did regarding chromium (VI) in drinking water.  Since then there have been a lot of newspaper and other media reports coming out talking about the same thing, so here’s some background info on the whole issue.  Chromium (VI), which you’ll also see as chrome(VI), chrome-6, chromium-6, Cr (VI), hexavalent chromium, and many other variations on that theme, is a form of the metallic element chromium, which you used to be able to find on the bumper of every car.  Other uses for this metal have included plating of other metallic parts; manufacturing stainless steel; producing dyes; as a wood preservative; and as an additive for anti-corrosion purposes.  The (VI) or 6 part is a chemical designation that refers to what’s called the oxidation state of the element, which relates to the number of electrons the atom has. In this case, it is the highest oxidation state of chromium, the others being (II) and (III), with (III) being by far the most common. Although too much chromium in any state would not be good to eat, it is the highest oxidation form, chromium (VI) which is most reactive, and therefore of greatest concern from a health perspective. Small quantities of chromium (III) are actually required by all of us for proper sugar metabolism, but because chromium (VI) is so much more reactive, it can be disruptive to cellular metabolism and is a proven cancer causing agent when inhaled; it’s effect when ingested at low levels is still open to debate.   Although there is no EPA or state regulation requiring monitoring or treating for Cr (VI), a Public Health Goal (PHG) of 0.02 ug/L has been proposed in California.  Once a PHG has been formalized, then the process for determining an MCL will begin, and will take into consideration the economic and technical aspects of treating for this compound.

What the Heck is Perchlorate?

With the problems with perchlorate in many areas of the United States that have been in the news and that many, if not all of you, have heard about, you may be wondering what this chemical is and why it’s a problem. So I thought I’d talk a little bit about that, as well as some rather peculiar relationships between perchlorate and another chemical a lot of people in the drinking water and waste water business work with every day – more on that later.
Perchlorate is the most highly oxygenated form of chlorine – a chlorine atom with 4 oxygen atoms attached (see chart below). Usually, the more oxygenated something is, the more unstable and reactive it is. But perchlorate is quite stable, although definitely reactive, and having a stable molecule that packs a lot of oxygen atoms and is normally found as a solid is what makes it so important in manufacturing. Of course, when it dissolves in water is when it’s a problem for many of us.

Perchlorate is valuable as a source of oxygen for combustion, which is why the solid rocket boosters of the space shuttle contain 350 metric tons of the stuff. That’s also why it’s widely used in road flares, fireworks, and other explosives, like the detonators that fill the airbags if your car is in an accident. When perchlorate gets into the groundwater or surface water and then into our drinking water, it can have serious health effects. Perchlorate is an endocrine disrupting compound (EDC) in that it affects the proper uptake of iodine by the thyroid gland, a part of the human endocrine system. Improper thyroid function can lead to osteoporosis, as well as problems with metabolism and body temperature regulation, among other things.
A related, but less highly oxygenated compound that is use every day in many drinking water systems to disinfect the water supply is hypochlorite, generally applied as sodium hypochlorite, a liquid, or calcium hypochlorite, a solid. Hypochlorite is a chlorine atom with one oxygen atom attached (see chart), and is an excellent disinfectant, ensuring that the water we drink is free of the harmful pathogens, such as cholera, that plague so many people in the world. But hypochlorite can change form and add oxygen atoms as it ages, changing into chlorite and chlorate, and eventually becoming perchlorate. That’s one reason it is recommended that hypochlorite is never stored for more than 30 days, because small amounts of perchlorate may be formed given the right conditions.