Geoscience Reference
In-Depth Information
Table 10.4
Data variables recorded on biosolids application data forms
Basic information
Date
Site
Site size
Site location
Application information
Liquid volume applied
Percent solids
Dry lbs. material
applied
Total dry tons
material applied
Tons per acre
-
-
-
Nutrients (mg/Kg)
Organic nitrogen
Ammonia nitrogen
Phosphorus
Metals (mg/Kg)
Arsenic
Cadmium
Copper
Lead
Mercury
Nickel
Zinc
Molybdenum
Selenium
-
-
-
Participating households were selected from within these buffers. Since more
health effects would be expected in areas with closer proximity and possibly higher
exposure, (i.e., closest to permitted fields) all houses located on permitted fields
were selected for inclusion. A similar number of houses were randomly selected
from the houses within 1 mile of a permitted field and another group of houses were
randomly selected from the houses greater than 1 mile of a permitted field, of which
51%were between 1 and 2 miles and 49%were between 2 and 3 miles of a permitted
field. Houses more than 3 miles from a permitted field were excluded from the study
due to the small number of houses in those buffers. Ultimately, the respondents were
put into two groups, households up to one mile from a field and households greater
than one mile from a field. These same two distance groups were used in all three
studies. Figures
10.5
,
10.8
and
10.9
depict a one mile buffer around the permitted
fields for Lucas and Wood Counties and around confirmed applied fields for Greene
County.
Survey groups for the epidemiological study were partitioned into households
that were within one mile of several permitted fields (heretofore the exposed
group) and households that were further than one mile away from any permitted
field (heretofore the unexposed group). Epidemiological surveys were sent to the
addresses chosen randomly from the generated lists. The use of GIS in the selection
of survey households allowed for a random selection sample rather than a conve-
nience sample of potentially exposed populations living near biosolids permitted
fields and eventually biosolids applied fields. A convenience sample would not have
guaranteed potentially exposed respondents. Additionally, the ability to verify the
presence of a household on a property prior to mailing reduced the potential for
returns due to bad addresses. This was especially true with dealing with agricultural
areas as many properties have addresses but no one resides on the property. In addi-
tion, for Wood and Lucas Counties, many surveys were returned without delivery
with
Address Unknown
on the envelope. In the process of generating addresses for
the survey, we did not check to see if there was a house on the parcel. For Greene
County, prior to household inclusion, a visual inspection of aerial photographs was
performed to ensure that a residence was present on the parcel.
