Tuesday, July 11, 2006

Big, bad asbestos and your garden

As though the warnings about lavender and tea tree oil that I summarized in the last post weren't enough, the July 8 issue of Science News has this article: Dirty little secret: asbestos laces many residential soils (available online for non-subscribers). We're not talking about houses built on old waste dumps, either. Asbestos is a mined mineral, and when asbestos-containing deposits are found near the surface, disturbances (such as the housing development described in the article) can send the cancer-causing fibers flying. Though the fibers in question are larger and don't drift as far as those released from old insulation materials and other asbestos found in old buildings, they do pose a risk when they're kicked up by wind or machinery. Unfortunately, though asbestos use in construction and its removal from old buildings are highly regulated, there are no laws restricting construction on sites where veins of asbestos-containing minerals have been uncovered.

But even if your home isn't built on a tremolite vein (one common asbestos-containing mineral), concerns about asbestos contamination of vermiculite mines a few years ago had gardeners and horticulturalists up in arms. Vermiculite, of course, is the stuff put in potting mix to lighten it while helping retain water. Experienced gardeners know you can buy it by the bagful if you want to create your own potting mix. It's also mixed into fertilizers, and has dozens of commercial and industrial uses, from fireproofing to nuclear waste disposal.

So what's a gardener to do? If you use vermiculite, the EPA recommends these steps to reduce exposure to the dust:
  • Use vermiculite outdoors or in a well-ventilated space (outdoors is best).
  • Dampen vermiculite before using it to prevent dust from flying.
  • Use purchased, moist potting mixes to reduce total vermiculite exposure.
  • If using vermiculite outdoors, peel off outer layers of clothing before going inside, and wash them.
A dust mask might not be a bad idea, also.

The National Cancer Institute has more recommendations for reducing cancer risk from asbestos.

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