From Journal of Pesticide Reform, 1991. The toxic chemicals in treated poles seep out when poles are in place. The chemicals can be carried into both surface and groundwater in concentrations that can contaminate drinking water and impact the life of aquatic organisms. Three poles treated with penta and located adjacent to drinking water wells caused water contamination. Retreatment Retreatment processes and chemicals Treated wood poles have a life expectancy of about 40 years, with considerable variability depending on tree species, treatment method, and climate.
Utilities companies vary in their approaches to retreatment.
Other utilities have discontinued their inspection and retreatment programs, in one case for budgetary reasons. Retreatments may be applied either externally or internally. External treatments are used mostly with Southern or Ponderosa Pine and sometimes with Douglas Fir and Lodgepole Pine treated with penta. Fumigation, in which a volatile liquid or solid is placed into an inspection hole, which is plugged. Retreatment chemicals expand the number of hazardous chemicals associated with the use of chemically treated wood poles.