2013 08 16: borate is used to protect against termites. it is dyed green, i suppose so the applier can see that it has been treated. this is a relatively benign protection. the epa says:
“Borate preservatives (Disodium Octoborate Tetrahydrate or DOT) are low toxicity alternatives for protecting timber and composites from wood destroying organisms such as decay fungi and termites. They have proven effective for more than 70 years in residential and commercial construction, and their efficacy is backed by extensive field testing.
Borates are naturally occurring minerals that exist in trace amounts in rock, soil, water and all living things. Consequently, they have marginal environmental impact. Borates are also essential for plants, nutritionally important for people and key ingredients in fiberglass, glass, ceramics, detergents and fertilizers.”