Over the last year Iíve received several emails from pet owners worried about the safety of wood shavings used as bedding for their animals. There are different wood shaving types available - pine shavings are in widespread use and cedar and spruce shavings are marketed in the US. Many of the queries have been from the US and concern cedar shavings. I posted a message on the hamster Internet newsgroup (alt.pets.hamsters) and received some very helpful replies and useful information about wood shavings.
Wood shavings are popular because they are cheap, absorbent and reduce the odour from urine. They also have natural insecticidal properties and inhibit the growth of bacteria. They also kill or inhibit the spread of fleas, mites and other parasites. Wood from western red cedar (Thuja plicata) has one of the most potent insecticidal compounds, which accounts for its popularity to repel or kill clothes' moths.
These benefits come with a price tag. The chemicals in the wood that give it insecticidal and bactericidal properties are also irritant to the lungs and upper air passages. The main irritant in cedar is plicatic acid and western red cedar contains the highest concentrations. In pine, the main irritant is abietic acid, sometimes called sylvic acid. Studies in humans exposed to cedar and pine wood over long periods of time have shown a clear link with chronic chest disease1. There is also a possible link with cancer and liver damage but the results of various studies are unclear and conflicting (there is an excellent review of these studies by Laura Tessmer at cavycages.com/pine.htm). There is no reason to believe that the effects in rodents are any less significant and indeed they may be more significant given that rodents have a high metabolic rate and short lifespan.
To be fair, the evidence against pine shavings is less compelling compared with the evidence against cedar and claims that pine shavings are unsafe are disputed. What types of bedding are safe? Well, hard woods such as aspen are generally chemical-free and pine is often treated by kiln-drying which is believed to make it safer. There are many paper-based bedding products on the market and these are my preferred bedding type. Avoid the fluffy, cotton-wool type bedding at all costs! A campaign is in progress to have this type of bedding removed from the market.
In summary, we should be avoiding cedar shavings completely, and perhaps we should be checking that pine shavings are appropriately treated before being packaged as a bedding material.
Reference: 1. Respiratory toxicity of cedar and pine wood, Jeff Johnston
The deadline for submissions for the next journal is 5th January 2001. Merry Christmas!