Sludge is a compendium of thousands of chemicals of biological and manmade origin.  Less than 5% of the constituents of sludge have ever been examined and only about 1% has been assayed with any frequency.  Sludge concentrates many of the contaminants in sewage.  Hence its composition mirrors the diverse chemicals released to wastewater treatment facilities.  The consequences of exposure to sludge will vary as a function of the environmental situation in which it is applied, the manner of application and the proximity of vulnerable human and wildlife populations.  To date we have barely scratched the surface in terms of understanding sludge composition, let alone the myriad of breakdown products, transport and fate and the potential effects on humans and the environment.  Many constituents will act in combination, akin to swallowing a multitude of medicines together without knowledge or consideration of any negative interactions.  The more you ingest, the greater the risk.  The diversity of chemicals in sludge exceeds that in any pharmacy storeroom. 

Odor is specifically mentioned in the proposed regulations (510 3.d).  Odor is a response of our biological receptors to contact with a chemical or chemicals.  Thus perception of an odor confirms chemical exposure, as well as off-site transport of these chemicals.  Humans have evolved to recognize odors associated with potentially dangerous situations, such as decaying food, dead bodies and excrement, all of which can transmit disease. These odors register as “unpleasant”.  We are programmed to avoid them.  As such, continued exposure to offending odors negatively impacts our sense of well-being and health.  This is particularly problematic when no avenue for escape exists, such as when the odors enter and remain in our home environment.  Commonly reported symptoms associated with nearby sludge applications are nausea and headaches, with attendant increases in stress and its associated consequences. 

While extension of buffers to protect “odor-sensitive individuals” may have positive consequences, we must be wary of simply removing the odor “canary in the coal mine”.  Many chemicals to which we can be exposed do not produce an odor, even at potentially toxic levels.  Toxic chemicals may not track precisely the fate and transport of odor-producing ones. The proposed changes in regulations do not eliminate the release of any chemicals.    Virginians have reported respiratory symptoms consistent with airborne exposure to irritants which may relate to exposure to some of these chemicals.  The proposal here may increase public acceptance of land application, but may not adequately protect “health, safety and welfare of citizens”…the stated purpose. 

With respect to forest applications of sludge, wildlife inhabit and are free to enter and leave areas where sludge is applied.  Hence they can be directly exposed to contaminants therein.  Hunters may also be vulnerable due to the nature of forest applications.  Unincorporated sludge on grazing pastures represents another area where risk is greater. Increased buffers alone will not impact these issues. 

Despite the above-mentioned uncertainties, the practice of land application of sludge on forests and agricultural fields (the source of our food supply) has often been labeled “safe”.  This conclusion conflicts with the basic tenets of scientific risk assessment, as well as common sense.  It is not “sound science”.  More information is needed before this conclusion can be reached and adequate regulations, protective of humans and the environment, designed.  To date more resources have been expended to increase “public acceptance” than to evaluate uncertainties and establish risks.  In some cases efforts have been made to discourage independent investigation.  Until we better understand the composition and consequences of reintroduction of these wastes back into the environment the effectiveness of regulations in meeting their stated purpose will remain uncertain.