US Government warns of ‘potential risk to workers’ using common vermiculite granules

The US Government’s Environmental Protection Agency (EPA) made the announcement on 22 August after becoming concerned about the mineral from news stories linking asbestos contaminated vermiculite from a closed mine in Libby, Montana to the deaths of more than 200 mineworkers and Libby residents. It also said that there was ‘a minimal risk to consumers who use vermiculite in gardening’ after finding low levels of asbestos. In that case vermiculite ore from the mine was found to be laced with tremolite, a rare, particularly dangerous type of asbestos.

Vermiculite is a granular substance mined for uses in horticultural products, such as pesticides, and insulation materials. For lawn and garden uses, it is often sold straight to be mixed with soil by the consumer or in pre-mixed potting soils, promoting faster root growth and giving quick anchorage to young roots.

“EPA is making this information available as part of our effort to expand the public’s right to know and protect public health and the environment,” said Susan Wayland, Acting Assistant Administrator for the Office of Prevention, Pesticides, and Toxic Substances. “We tested a number of bags of straight vermiculite and pre-mixed potting soil that contained vermiculite. Low levels of asbestos were found in a handful of these bags, primarily those bags of straight vermiculite. These levels were very low and do not pose significant health risks. However, we feel it is important for consumers to be armed with this information when making their decisions.”

EPA analysed 16 vermiculite products from the Seattle area and found that one contained asbestos at a level ‘that could pose a potential for exposure’. Then 38 vermiculite products from across the country were studied; five were found to contain similar level of asbestos and a further 12 contained trace amounts of the substance.

EPA recommends that consumers use pre-mixed potting soils, which ordinarily contain more moisture and much less vermiculite than pure vermiculite products and are therefore far less likely to generate any potentially dangerous dust which might be inhaled. EPA also recommends consumers to purchase soil supplements other than vermiculite, such as peat, sawdust, perlite or bark. It also advises consumers who are mixing vermiculite-only products with soil, do so outdoors or in a well-ventilated area, keep the vermiculite damp during use to avoid dust, and avoid bringing dust into the home on clothing. Workers handling vermiculite are advised to use dust respirators and safety goggles.

The US Government is also developing a set of standard scientific protocols for sampling in-place vermiculite insulation in the attics and walls of people’s homes to help assess the potential health risks.