The inactivation of radioactively labeled poliovirus type 1 and coxsackievirus B 1 in soils saturated with surface water, groundwater, and septic tank liquor was directly proportional to temperature. Virus persistence was also related to soil type and the liquid amendment in which viruses were suspended. At 37°C, no infectivity was recovered from saturated soil after 12 days; at 4°C, viruses persisted for at least 180 days. No infectivity was recovered from dried soil regardless of temperature, soil type, or liquid amendment. Additional experiments showed that evaporation of soil water was largely responsible for the decreased recovery of infectivity from drying soil. Increased rates of virus inactivation at low soil moisture levels were also demonstrated. Increasing concern over efficient use of limited water resources has resulted in research on the possible use of sewage or sewage sludges for land reclamation and fertilizer (9, 14, 18). Viruses and other pathogens remaining in the sewage or sludge could contaminate crops, surface water, or groundwater. For viral contamination to occur, however, viruses must remain infectious after a period of association with soils. Knowledge of virus persistence and movement in soils is presently incomplete and sometimes contradictory. For example, Tierney et al. (19) have shown that viruses in sewage or sludge used to irrigate crops may persist for up to 11 days in soil at summer temperatures and for over 96 days under winter conditions. Wellings et al. (23) demonstrated that enteric viruses can survive irrigation and move at least 6 m vertically and 38 m laterally through soil to monitoring wells.

The effects of moisture content on the survival and regrowth of seeded and indigenous enteric bacteria in raw sludge were determined. Cultures of six strains of fecally associated bacteria grown in sterilized, liquid sludge (5% solids) were all quite stable at this moisture level for over 90 days at 21 degrees C. When the moisture content of the sludge containing these organisms was reduced by evaporation and the samples were stored at 21 degrees C for extended periods, bacterial inactivation rates were generally proportional to the moisture losses of the samples. A dramatic reversal in this effect was observed in samples containing more than 90% solids. In this dried sludge, every bacterial species studied except Proteus mirabilis was found to be extremely stable. Bacteria indigenous to sludge were also found to survive for long periods in dried sludge. Regrowth of bacterial isolates in sterilized raw sludge was found to occur readily at 37 degrees C in samples containing less than or equal to 75% solids, but no growth was observed in samples with greater than or equal to 85% solids. Some growth, but to less than saturation densities, occurred with 80% solids. Growth of seeded Salmonella typhimurium was also found to occur in the presence of indigenous organisms in both liquid and dewatered raw sludges. However, the population density attained was well below that found in sterilized samples of the same sludges. In addition, the number of salmonellae dropped below detectable limits within a few days in sludges containing viable indigenous organisms, whereas little decrease occurred during this time with salmonellae grown in previously sterilized sludges.

The loss of infectivity of poliovirus in moist and dried soils was a result of irreversible damage to the virus particles. The damage included (i) dissociation of viral genomes and capsids and (ii) degradation of viral ribonucleic acid (RNA) in the soil environment. Under drying conditions, capsid components could not be recovered from the soils. Further studies in sterile soils indicated that, under moist conditions, the viral RNA was probably damaged before dissociation from the capsid. However, in sterile, dried soil, RNA genomes were recovered largely intact from the soil. These results suggest that polioviruses are inactivated by different mechanisms in moist and drying soils.

Two studies were carried out to determine the influence of moisture content of the survival of bacteria in raw wastewater sludge. The first study involved the effect of water loss by evaporation on the bacterial population. The second used these dewatered samples to measure the effects of moisture content on the inactivation of bacteria sludge by ionizing radiation. Both studies involved survival measurements of six representative fecally associated bacteria grown separately in sterilized sludge as well as survival data on bacteria indigenous to sludge. Growth of bacteria was stimulated in sludge during the initial phase of moisture removal by evaporation, but the reduction of moisture content below about 50% by weight caused a proportional decrease in bacterial numbers. In comparison with the original sludge, this decrease reached about one-half to one order of magnitude in all dried samples except those containing Proteus mirabilis, which decreased about four orders of magnitude. The rates of inactivation of bacteria by ionizing radiation in sludge were usually modified to some degrees by variations in moisture content. Most bacteria were found to be somewhat protected from ionizing radiation at reduced moisture levels. The largest effect was found with Salmonella typhimurium, whose radiation resistance approximately doubled in dried sludge. However, no excessively large D10 values were found for any bacterial species tested.

Gamma radiation from cesium-137 has been shown to be effective in reducing pathogens in sewage sludge to levels where reuse of the material in public areas meets current regulatory criteria for protection of the public health. A 7,250-kilogram per day pilot plant is in operation and full-scale demonstration facilities are being developed. This paper discusses program research and engineering history related to sludge irradiation, as well as current activities and future plans.

was treated with ceftriaxone, vancomycin, azithromycin, and bicarbonate. Potassium and magnesium were replaced. She expired despite all resuscitative measures which included mechanical ventilation and vasopressor support. The majority of tenofovir associated nephrotoxicity has been reported in the HIV population. To our knowledge, this is one of the rare cases reported in a non-HIV patient. The patient's non-anion gap metabolic acidosis, hypokalemia, glucosuria, proteinuria, ketonuria, multiple spontaneous rib fractures and osteopenia were consistent with Fanconi's syndrome. The severity of the acidosis and renal failure likely contributed to this patient's inability to withstand the stress of severe sepsis. Recently the WHO has issued guidelines regarding the management of renal diseases in patients being treated with tenofovir for chronic hepatitis B that include obtaining baseline and biannual renal indices. Tenofovir induced renal failure and Fanconi's syndrome can significantly worsen the prognosis of patient with severe sepsis.