Robert C. Cooper

Comparison of aerobic and anaerobic methylation of mercuric chloride by San Francisco Bay sediments

Abstract The methylation of mercury under aerobic and anaerobic conditions was examined in three types of sediment collected from San Francisco Bay. The net amount of methylmercury produced under anaerobic conditions was greater than that found under aerobic conditions for all three sediments tested. The amount of organic matter in sediments greatly affected methylation capability. There are indications that methylmercury produced in anaerobic sediments is more stable than that produced in aerobic sediments.

Asbestos in drinking water and cancer in the San Francisco Bay Area: 1969-1974 incidence.

The relationship between ingested asbestos (through drinking water) and cancer of various body sites was examined. This study was a follow-up to another article that investigated this relationship. Age-adjusted, sex and race specific 1969–1974 cancer incidence ratios for 410 census tract groupings (‘super tracts’) of the San Francisco-Oakland Standard Metropolitan Statistical Area were compared with measured chrysotile asbestos counts in drinking waters of super tracts. The earlier article analyzed cancer data for the 3 yr period, 1969–1971. The present study used that data and an added set of cancer cases for 1972–1974. The water supplies serving the area have varying contact with naturally occurring serpentine. The t-test for multiple regression coefficients and the t-test for correlation coefficients showed significant (p < 0.01) relationships between chrysotile asbestos content of super tract drinking water and white male digestive tract, esophageal, stomach and pancreatic cancers. For white females, significant (p < 0.01) relationships on these tests were found for esophageal, stomach, digestive related organs, and pancreatic cancers. These associations appeared to be independent of income, education, asbestos occupation, marital status and mobility.

Enteric virus survival in algal-bacterial wastewater treatment systems—I: Laboratory studies

Abstract The survival of a representative enteric virus, poliovirus type 1, in laboratory models of algal-bacterial sewage treatment systems and the interactions of poliovirus with stabilization pond water was studied. In laboratory reactors a fraction of the total poliovirus present rapidly adsorbed to stabilization pond water solids by a reversible process, conforming to a Freundlich adsorption isotherm. In laboratory cultures the growth of Scenedesmus quadricauda and Bacillus megaterium in sterile sewage had no detrimental effect on poliovirus survival, whereas the growth of heterogeneous populations of stabilization pond bacteria in the same medium resulted in substantial virus inactivation. Appreciable poliovirus inactivation occurred in laboratory cultures of mixed algal-bacterial populations obtained from stabilization ponds. Because the degree of antiviral activity in these cultures was greater than that in cultures of stabilization pond bacteria alone, additional microbial factors must contribute to this virus inactivating phenomenon. The results of this study suggest that in algal-bacterial treatment systems both virus adsorption to solids and virus inactivation due to microbial activity play a role in reducing the enteric virus concentration in wastewater.

Risk-Based Review of California’s Water-Recycling Criteria for Agricultural Irrigation

AbstractCalifornia currently recycles treated wastewater at a volume of approximately 8.0×108  m3 of water per year, with a potential to recycle an additional 1.9×109  m3 per year. A key challenge in promoting the expansion of water recycling for agricultural purposes was addressing the perceived concern about whether recycled water produced in conformance with California law is protective of public health. The California Department of Public Health (CDPH) established an expert panel to consider the concern. The panel found, based on quantitative microbial risk assessment (QMRA), that the annualized median risks of infection for full tertiary treatment ranges from 10−8 to 10−4 (for human enteric viruses Cryptosporidium parvum and Giardia lamblia, and Escherichia coli O157:H7) based on the assumption of daily exposure. The panel found that risk estimates are consistent with previous CDPH estimates and concluded that current agricultural water recycling regulations do not measurably increase public health risk.

Virus survival in solid waste leachates

Abstract Disposal of domestic solid waste either in open dumps or in sanitary landfills results in leachates which may find their way into groundwater aquifers. This study is concerned with the survival of microorganisms of sanitary significance, with particular emphasis on enteric viruses, in leachates produced by model disposal systems. Data are presented that indicate the presence of considerable amounts of human and animal feces in fresh domestic refuse. Significant numbers of coliforms, fecal coliforms, and fecal streptococci are present in refuse and also persist for weeks in the leachates produced. A method for the concentration and recovery of virus from relatively large volumes of leachate is evaluated. Viruses were sporadically recovered for periods up to 20 weeks from leachates generated by systems to which poliovirus was purposely introduced as well as from control systems. The leachates produced were shown not to be acutely toxic to poliovirus.

City of San Diego potable reuse of reclaimed water: Final results

Abstract Water reclamation is becoming a common component of water resource planning. In the past the driving motivation for water reuse was to provide a means of avoiding effluent disposal into surface waters. With continued drought and increased water demand reclaimed wastewater is now considered an important water resource. Nonpotable and potable use of reclaimed water can enable communities to maximize and extend the use of limited water resources. This paper summarizes results from the Health Effects Study (HES) portion of the City of San Diegos Total Resource Recovery Project, which includes study and implementation of an advanced wastewater treatment system. The HES represents the product of a substantial research effort to estimate the potential health risk associated with the reclaimed water relative to an existing raw water supply to the City.

Fish toxicity of jet fuels. I. The toxicity of the synthetic fuel JP-9 and its components

Abstract The toxicity of the jet fuel JP-9 and its components RJ-4, RJ-5 and MCH was assessed in static bioassays on the warm water fish, golden shiner (Notemigonus chrysoleucas). The 96-h LC50 of emulsions was 2.0 mg 1−1 for JP-9, 0.51 mg 1−1 for RJ-4, 0.61 mg 1−1 for RJ-5 and 72 mg 1−1 for MCH. As determined by the 96-h LC50 values unemulsified fuel (pools of fuel) JP-9 was 235 times less toxic, RJ-4 was 196 times less toxic, RJ-5 was 7700 times less toxic and MCH was 3.3 times less toxic than the corresponding emulsified materials. In continuous flow bioassays with the water soluble fraction of the fuel and its components the effect on egg hatchability and fry development of flagfish (Jordanella floridae) and rainbow trout (Salmo gairdneri) was studied. The no effect of level on flagfish egg hatchability was 0.23 mg 1−1 for JP-9 and 0.05 mg 1−1 for RJ-5. Concentrations of 0.83 mg 1−1 MCH and 0.2 mg 1−1 RJ-4 did not affect egg hatchability. In rainbow trout studies 97-day LC50 values for RJ-4 and RJ-5 were 0.045 mg 1−1 and 0.072 mg 1−1, respectively, and 23-day LC50 values for JP-9 and MCH were 0.26 mg 1−1 and 1.3 mg 1−1, respectively. The accumulation of fuels in fish bodies was studied and it was found that flagfish can tolerate a total body burden of 0.5 mg MCH g−1 wet weight without lethality. It was also found that body burdens of 0.43 mg RJ-4 g−1 and of 0.27 mg RJ-5 g−1 on a wet weight basis will produce 50% mortality in rainbow trout. Voiding of MCH from fish bodies occurs readily in fuel-free water, but RJ-4 and RJ-5 are retained in the tissues.

A natural mutant of plasmid RP4 that confers phage resistance and reduced conjugative transfer

A natural isolate of RP4 (PRC#116) acquired from the Stanford University Plasmid Reference Center differed from the wild-type Incompatibility Group P plasmid in several respects. Cells of Escherichia coli harboring PRC#116 were resistant to the IncP pili-specific bacteriophage PRD1 and GU5, and transferred this plasmid at a lower efficiency than the wild-type RP4. Phage sensitivity was restored, and transfer considerably improved in PRC#116+ bacteria transformed with plasmid constructs containing the origin of transfer (oriT region) of RP4. Mutant RP4 plasmids equivalent to PRC#116 were selected at a high frequency from an RP4+ E. coli population infected with PRD1 indicating that this RP4 variant may be the product of a very common mutation of the wild-type plasmid.

The hygienic aspects of wastewater reuse

Historically drinking water contaminated with wastewater discharged from nearby communities has been a major public health problem whose solution was directed towards the treatment of drinking water rather than of the source of contamination. The increased need for deliberate wastewater reuse has stimulated greater interest in the ability of wastewater treatment processes to produce a product in which the risk of infection, upon reuse, is reduced to an acceptable level. A brief overview of the disease agents involved, human dose-response considerations, microbial standards, and treatment plant reliability is presented. Selected experiences with the question as to how our terrestrial experience can be applicable to advanced life support systems is addressed.