THMs : What are they and why are they dangerous?

There has been a lot of talk about THMs (trihalomethanes) recently and there have been more studies published recently which brings new light on how they effect the body and the degree in which they actually can cause cancer. Therefore in this article we will explore THMs in more detail than we have before. We will look at what THMs actually are, how they are used in the every day world, how they are produced and also look at the studies that reveal how THMs can be hazardous to humans. Finally in this article we will discuss methods in which we can eliminate THMs from our homes and thereby create a healthier environment.

So what exactly are THMs?

There are actually 7 different types of THMs - they are all chemical compounds. The majority of literature discussing THMs focus on the presence of THMs in drinking water and shower water in our homes, as toxic by-product of the chlorination process of water, it is often forgotten that THMs actually have a commercial and industrial usage as well. THMs are actually used within refrigerants and in this usage are known to have an adverse effect on the ozone layer as these THMs are released into the atmosphere. They are also used very widely as solvents. In fact Chloroform is an extremely common type of solvent, you will find it in nearly all chemistry labs as it is used as an inexpensive cleaning agent.

All world governments and health organisations classify THMs as an environmental pollutant and they are regarded as a carcinogenic toxic chemical. There is no instance where the usage of THMs is beneficial for our environment or our health. This is the exact reason why there is a large amount of conce
regarding THMs in our drinking and shower water. THMs are produced as a by-product of the chlorination process of tap water. When chlorine that is added to water, it reacts to organic materials that are naturally found in water. For example water in reservoirs often contain harmless organic material such as dead leaves, algae or river weeds. When residual chlorine reacts with these organic materials they produce THMs, which are tasteless and odorless but are extremely toxic.

THMs produced in water stay present in that water until they reach the point of their use, whether that be in the kitchen or in the bathroom or anywhere else around the house. They are a very volatile chemical and when water with THMs is exposed to air it usually dissipates into the air. Therefore the World Health Organisation states that exposure to THMs (chloroform) is particularly hazardous to individuals during showering in chlorinated tap water, because of inhalation of the THM and dermal exposure during showering and bathing.

What studies have been conducted on THMs?

A large study by the University of Florida report that exposure to THMs can increase the risk of cancer. Rebekah Grossman stated in the report that Chloroform and dibromochoromethane are both carcinogens and a different type of THM (bromodichloromethane) has the ability to mutate and alter DNA. A different study in Califo
ia proved that THMs might actually be responsible for miscarriages and trouble with reproductive systems. This study showed that there was a 15.7 percent rate of miscarriage for women who drank five or more glasses of cold water containing more tha
0.075 mg/l of TTHM, compared to a much lower rate of 9.5 percent for women who drank water with lower TTHM contents.

A study in 2002 of 50 women living in Georgia and Texas showed that showering increased the levels of THMs in the blood by a factor of four.

How can we remove THMs from our home environments?

Our THMs exposure is greatest in our bathrooms. THMs are volatile chemicals which are released into the air we breath very easily. In an environment where water is heated and liquids are turned into gas from hot steamy showers we run the risk of high levels of exposure of THMs from the air and also from open pores in our skin. Additionally our bathrooms are generally smaller than other rooms in or homes, therefore in this smaller tight space, there is a higher concentration of THMs in the air we breath then for example somewhere like our kitchens.

We must ensure that we remove chlorine from our showers and baths through use of shower filters, bath filters and even basin filters. The contents of these filters may include any type of dechlorination material, from the very inexpensive Granulated Active Carbon to more expensive and higher quality KDF type dechlorination mediums.

In bathrooms there should always be adequate ventilation, whether that be in the form of windows or extraction fans. It is vital to ensure that our bathrooms do not become a 'tomb' of highly concentrated toxic fumes.

In the kitchen we should always filter our water before using it for drinking or cooking. Though generally if we leave water uncovered for a while most THMs exposed to air in this water will naturally expel itself. Still pregnant women should take extra care to avoid drinking or being exposed to water with high THM content.