Sludge Watch ==> Transport of sludge pathogens - through air, runoff, sediment

[maureen.reilly at sympatico.ca]

>From Dr Edo McGowan:

Maureen, in one of your recent posts when talking of sewer sludge, you 
note-----These toxic substances not only adversely impact the soil but also 
travel off sludge sites through air and water. Studies show that viruses can 
be airborne at least a quarter mile from the sludge site.

To expand on this, we need to also talk about water transport of sewer 
sludge from application sites. Water transport can take viruses and other 
pathogens for hundreds of miles. Thus if one looks at sludge applied fields 
that have runoff or irrigation return, there is no reason to assume merely a 
quarter mile. Consequently, the Hinkley site with storm water runoff 
potential is a worrisome situation. Further, once beyond the applied field 
who is looking for the contamination, it is seldom a monitoring issue and 
moreover, will bacterial indicators be are all that may be used, thus no one 
will ever know (see Gerba below)?

If San Bernardino County Health, for examle,  refuses or is reluctant to 
monitor in the cases of sewer sludge land application, considerable 
contamination may actually be accruing to this land spreading activity. 
Additionally, as noted in the Sugar Creek study (see below) the movement of 
biosolids from fields into water transport mechanisms has been 
demonstrated---the king's new clothes are there for all to see if regulators 
just honestly look. Additionally, as I have previously demonstrated, the 
nematodes, in their gut bacteria, can spread pathogens readily from field to 
field via mud sticking to wheels of equipment. This is a known fact. 
Nematodes are found in almost all soils.

The work of Chuck Gerba tends to show this easy movement of pathogens with 
sediment, hence transport via water, see abstracts below. Further, the 
standards used are inadequate, as noted by Gerba--- (Viruses were detected 
periodically in waters that met current bacteriological standards for 
shellfish harvesting).

Thermostabilization of enteroviruses by estuarine sediment.

Liew PF, Gerba CP.

The effect of estuarine sediment on the thermoinactivation of poliovirus 
type 1 and echovirus type 1 was evaluated. Poliovirus survival was prolonged 
at 24 and 37 degrees C but not at 4 degrees C in the presence of sediment 
over the time periods observed. Further inactivation studies were performed 
at 50 and 55 degrees C to maximize the thermal effects, and similar 
protection was observed. The supernatant fluid from a mixture of seawater 
and sediment lacked the protective effect against thermoinactivation, 
suggesting that prolonged virus survival in the presence of sediment was due 
to adsorption to particulates. From these observations, it appears that the 
adsorption of enteroviruses to estuarine sediments may play a significant 
role in protecting them against thermoinactivation.
++++++++++++++++++

Influence of estuarine sediment on virus survival under field conditions.

LaBelle RL, Gerba CP.

The survival of poliovirus 1 (LSc) and echovirus 1 (Farouk) in estuarine 
water and sediment was studied in Galveston Bay, Texas. Viruses were 
suspended in estuarine water and sediment both in dialysis tubing and in 
chambers constructed with polycarbonate membrane walls. Virus inactivation 
rates in seawater were similar in both types of chambers. Virus adsorption 
to sediment greatly increased survival time. The time required to inactivate 
99% (T-99) of poliovirus increased from 1.4 days in seawater alone to 6.0 
days for virus adsorbed to sediment at a relatively nonpolluted site. At a 
more polluted site, poliovirus T-99 was increased from approximately 1 h to 
4925 days by virus adsorption to sediment. This study demonstrates that 
under field conditions virus association with estuarine sediment acts to 
prolong its survival in the marine environment.

NOTE HERE THAT 4925 DAYS IS 13.5 YEARS, AND FROM THIS ONE MAY ASSUME THAT 
THERE IS AMPLE TIME FOR MOVEMENT OF SEDIMENT FOR HUNDREDS OF MILES. IN MANY 
AREAS HARBORS ARE DREDGED AND SPILLED SEWAGE MAY BE PUMPED LATER BY DREDGE 
DOWN THE BEACH TO WHERE ALL THE TOURISTS PLAY ON THE BEACH WITH THEIR 
CHILDREN. ++++++++++++++++++++++++++++++

Influence of pH, salinity, and organic matter on the adsorption of enteric 
viruses to estuarine sediment.

LaBelle RL, Gerba CP.

This study was designed to determine the degree of adsorption of enteric 
viruses to marine sediment and factors controlling this association. 
Adsorption and elution characteristics of several enteroviruses and one 
rotavirus to estuarine sediments were studied under varying conditions of 
pH, salinity, and presence of soluble organics. Greater than 99% of the 
added poliovirus type 1 (LSc), coxsackievirus type B3 (Nancy), echovirus 
type 7 (Wallace), and rotavirus (SA-11) adsorbed to sediment. Echovirus 1 
(Farouk) and a recent isolate typed as coxsackievirus B4 adsorbed 
significantly less than poliovirus 1 under similar conditions of varying 
salinity and pH. The presence of soluble organic matter, in the form of 
secondary sewage effluent or humic acid, did not affect these patterns of 
adsorption. Only echovirus 1 (Farouk) desorbed when the pH or salinity was 
altered and then only to a small extent. Three recent isolates of echovirus 
1 and echovirus 29 (strain JV-10) also demonstrated varying amounts of 
adsorption to sediment. These data indicate that enteric viruses can become 
readily associated with sediment in the estuarine environment and that this 
association may play a major role in their hydrotransportation and survival.

++++++++++++++++++

Human enteroviruses in oysters and their overlying waters.

Goyal SM, Gerba CP, Melnick JL.

The presence of enteroviruses in oysters and oyster-harvesting waters of the 
Texas Gulf coast was monitored over a period of 10 months. Viruses were 
detected in water and oyster samples obtained from areas both open and 
closed to shellfish harvesting. Viruses were detected periodically in waters 
that met current bacteriological standards for shellfish harvesting. No 
significant statistical relationship was demonstrated between virus 
concentration in oysters and the bacteriological and physiochemical quality 
of water and shellfish. Viruses in water were, however, moderately 
correlated with total coliforms in water and oysters and with fecal 
coliforms in oysters. Total coliforms in water were realted to total 
coliforms in sediment were related only to total coliforms in sediment. 
Among the physiochemical characteristics of water, turbidity was related 
statistically to the organic matter content of water and to fecal coliforms 
in water. There was a marked effect of rainfall on the bacteriological 
quality of water. Of a total of 44 water samples, 26 yielded virus in 
concentrations from 4 to 167 plaque-forming units per 100-gallon (ca. 
378.5-liter) sample. Of a total of 40 pools of 10 to 12 oysters each, virus 
was found in 14 pools at a concentration of 6 to 224 plaque-forming units 
per 100 g of oyster meat. On five occasions, virus was found in water 
samples when no virus could be detected in oysters harvested from the same 
sites. This study indicates that current bacteriological standards for 
determining the safety of shellfish and shellfish-growing waters do no 
reflect the occurrence of enteroviruses.

+++++++++++++++++

Role of sediment in the persistence of enteroviruses in the estuarine 
environment.

Smith EM, Gerba CP, Melnick JL.

The survival of four enteroviruses commonly found in sewage effluents was 
examined when the viruses were adsorped to marine sediments in estuarine 
water and compared with virus survival in estuarine water alone. Echovirus 
1, coxsackieviruses B3 and A9, and poliovirus 1 survived longer when 
associated with marine sediment. When the estuarine water was polluted with 
secondarily treated sewage effluent, virus survived for prolonged periods in 
sediments, but not in the overlaying estuarine water.
++++++++++++++++++++

Development of a quantitative method for detecting enteroviruses in 
estuarine sediments.

Gerba CP, Smith EM, Melnick JL.

Several investigators have reported on the detection of enteric viruses in 
marine sediments, but none determined the efficiency of their methods and 
only limited volumes of sediment were sampled. The purpose of this 
investigation was to develop a quantitative method for detecting 
enteroviruses in marine sediments so that their relative proportion to 
viruses freely suspended in estuarine water could be more accurately 
determined. Poliovirus was found to adsorb readily to natural marine 
sediments collected along the Texas Gulf coast. A number of substances were 
evaluated for their ability to elute adsorbed viruses. A solution of 10% 
fetal calf serum adjusted to pH 10.5 and 0.05M ethylenediaminetetraacetate 
(pH 11.0) were found to be the best eluents. Using 
ethylenediaminetetraacetate as an eluent, it was possible to elute virus 
from large volumes of sediment and reconcentrate the sediment eluate into an 
economically assayable volume (30 to 50 ml). Poliovirus could be recovered 
from the sediment with an overall efficiency of 50%. This method was found 
to be satisfactory for the recovery of naturally occurring animal viruses in 
estuarine sediments from the upper Texas Gulf coast.