Ka Man Lai

Shaping cities for health: complexity and the planning of urban environments in the 21st century

3·4 billion people—about half the world’s population--live in urban areas, and this number might rise to 6·3 billion by 2050.1 The proportion of the global population living in cities will be 60% by 2030,2 a 72% increase in 30 years (figures 1 and ​and2).2). Urban growth will be greatest in Africa and Asia, followed by Latin America and Oceania.5 Even in long-established urban areas in Europe, urban population growth during that period will reach almost 5%.5 This growth will not only result in more megacities (cities of more than 10 million people), increasingly concentrated in Asia, but also in more medium-sized cities, especially in Africa. UN estimates are that about 1 billion people, nearly a sixth of the global population, live in slum-like conditions. With the worldwide population predicted to expand to 9 billion by 2030, the number of people living in slum-like conditions could reach 2 billion.5 Figure 1 World population growth, 1950-2050 Figure 2 Proportion of the world population living in urban areas The understanding of how urban environments affect health outcomes and can produce health benefits is therefore an urgent priority, as recognised by WHO in their declaration of 2010 as the Year of Urban Health. From this perspective, there are reasons to be optimistic. The idea of the so-called urban advantage encapsulates the health benefits of living in urban as opposed to rural areas. However, factors such as economic growth and associated urban expansion cannot be relied on to drive improvements in health outcomes. Health improvements need to be actively planned for. The Healthy Cities movement has appreciated this fact and generated much action. Assessments have, however, pointed to a gap between aspirations and outcomes and limitations in the coherence of the models behind action. In response to this problem, the UCL Lancet Commission met from November, 2009, to June, 2011, bringing together an interdisciplinary team of experts to under stand how better health outcomes can be delivered through interventions in the urban environment in cities across the world, and to generate policy recommendations. We began with the definition of health as both the absence of ill health and the presence of mental and physical wellbeing,6 and the urban environment as the physical context within which urban activities take place, including the material fabric of buildings and infrastructure and their spatial organisation. The Commission focused on the potential for shaping the urban environment for better health outcomes; we explicitly did not address the issue of health-service provision within cities, but acknowledge that this is a key component of urban policy. We undertook expert-led reviews of available studies and desk-top research into the connection between urban planning and health in more than a dozen cities, with additional information provided by Commission members who have experience of working in many of these cities. The work informed discussions at monthly meetings with experts in public health, planning, architecture, building physics, engineering, development studies, anthropology, and philosophy. The Commission developed an approach based on complexity thinking—an approach that looks at the interconnected elements of a system and how that system has properties not readily apparent from the properties of the individual elements—and used this approach to develop proposals for an effective way forward. We begin by addressing the arguments around the urban advantage idea and then review the work of the Healthy Cities movement in the promotion of action for urban health. We then set out a complex systems approach for the understanding of how urban environments affect urban health, followed by five short case studies of urban interventions: the inter-related domains of sanitation and water management, building standards and indoor health, transportation and the links to mobility, urban form and the urban heat island effect, and the promotion of urban agriculture. We then turn to the implications of our analysis for urban governance if effective interventions to improve urban health are to be delivered, concluding with recommendations for policy and practice.

Prediction of the bioaccumulation factors and body burden of natural and synthetic estrogens in aquatic organisms in the river systems

This study undertakes an initial prediction of the bioaccumulation factors and body burden of the steroid estrogens, estrone, estradiol, estriol and ethinylestradiol in a range of aquatic organisms (plankton, benthic and free-living invertebrates and fish) in river systems using a food-web model. These data are compared to that derived from less complex predictions based on octanol-water partition coefficient and molecular connectivity index. The model predicted that bioaccumulation of steroid estrogens occurred in all organisms, however, the values were small, and the maximum and minimum bioaccumulation factors in this study were found in the fish at the lowest trophic level with ethinylestradiol (332) and the fish at the highest trophic level with estriol (1.8), respectively. Moreover, the bioaccumulation factors were sensitive to the metabolic rates of the estrogens in the free living organisms, while the concentration of estrogens in sediment was a significant factor in determining these values in benthic invertebrates. Biomagnification contributed little to the overall bioaccumulation, but the importance increased in fish exposed to ethinylestradiol. The predicted bioaccumulation factors from the food web model were generally smaller than the calculated bioconcentration factors from the simpler octanol-water partition coefficient/molecular connectivity index based estimates. Compared to literature measured data, the predicted values for fish were approximately 1000 times less than the values observed in laboratory tests, while for invertebrates, the modeled values were less than two orders of magnitude below laboratory results. However, the model predicted a similar bioconcentration factor for plankton in relation to experimental data for Chlorella vulgaris for estrone and estriol.

BIOTRANSFORMATION AND BIOCONCENTRATION OF STEROID ESTROGENS BY CHLORELLA VULGARIS

ABSTRACT The biotransformation and bioconcentration of natural and synthetic steroid estrogens by Chlorella vulgaris were investigated by using batch-shaking experiments with incubation for 48 h in the light or dark. Estradiol and estrone were interconvertible in both light and dark conditions; however, this biotransformation showed a preference for estrone. In the light, 50% estradiol was further metabolized to an unknown product. Apart from biotransformation, estrone, as well as hydroxyestrone, estriol, and ethinylestradiol, was relatively stable in the algal culture, whereas estradiol valerate was hydrolyzed to estradiol and then to estrone within 3 h of incubation. All of the tested estrogens exhibited a degree of partitioning to C. vulgaris; however, the concentrations of estriol, hydroxyestrone, ethinylestradiol, and estradiol valerate were always below the quantification limits. For estradiol and estrone, the partitioning of these estrogens in the algal extracts to the filtrates was <6% of the total amount present. The average concentration factor for estrone was ca. 27; however, the concentration factor for estradiol was not reported since no equilibrium was reached between the aqueous solution and that within the cells due to continuing biotransformation.

The effects of natural and synthetic steroid estrogens in relation to their environmental occurrence.

Laboratory-based acute toxicity data and physiological studies relating to natural and synthetic steroid estrogens in a range of animals and plants are reviewed. Steroid estrogens may induce adverse effects in animals that do or do not express the estrogen receptor, and in plants, and they may mimic other hormones or induce nonestrogenic effects. Although the findings of such studies should be treated with caution when extrapolated to possible environmental effects, the available data indicate that a wide range of effects may be manifested in a diversity of species. The environmental occurrence of the compounds and possible environmental exposure routes are also reviewed and discussed in relation to the laboratory-based acute toxicity data. While there are likely to be difficulties in relating some of the observed laboratory data to possible environmental effects, studies undertaken on fish are directly relevant because exposure pathways and concentrations were related to those occurring in the environment. Effects that may occur in the environment are discussed in relation to their significance to the individual and at the species level.

Isolation and Optimization of PAH-Degradative Bacteria from Contaminated Soil for PAHs Bioremediation

The objective of the present study is to isolate PAH-degradativebacteria from petroleum-contaminated soils and to optimize theirdegradative conditions including pH, glucose, nitrogen andphenanthrene concentrations required for bioremediationpurposes. Several bacterial strains were isolated throughenrichment and one strain, Burkholderia cocovenenans (BU-3)that was tentatively identified by the Biolog system,demonstrated a high removal rate of phenanthrene over otherstrains. More than 95% in 100 and 500 mg L-1 and 65% in1000 mg L-1 of phenanthrene contents was reduced in theculture media, respectively. Maximum rate of phenanthrene removalup to 4.2 mg hr-1 occurred in the culture containing 1000 mgL-1 phenanthrene. Media at a pH between 6.5 to 7.0 weremore favorable for the degradation of phenanthrene by BU-3.Although increasing glucose concentrations from 0.45 to 3 gL-1 resulted in a better bacterial growth of the isolatedbacteria, the degradation of phenanthrene was reducedsignificantly. Nitrogen supplement did not exert a significanteffect on bacterial growth and phenanthrene degradation. Theisolated Burkholderia cocovenenans BU-3 demonstrated to bea feasible strain for degradation of phenanthrene at a neutralpH, even up to a phenanthrene concentration of 1000 mg L-1.

Availability of Heavy Metals for Brassica Chinensis Grown in an Acidic Loamy Soil Amended with a Domestic and an Industrial Sewage Sludge

The use of sewage sludge on agriculture provides an alternativefor sewage sludge disposal. Therefore, it was the aim of thepresent study to evaluate the feasibility of using a domestic(Tai Po sludge) and an industrial (Yuen Long sludge) sewagesludge produced in Hong Kong for the growth of vegetable crops.The acidic loamy soil with or without lime treatment was amendedseparately with each sludge at application rates of 0, 5, 10, 25and 50% (v/v) for the growth of a common local vegetable crop,Brassica chinensis. The plant available metal contents, asindicated by the DTPA extraction, increased with an increase insludge amendment, but decreased with lime amendment at eachsludge application rate due to the reduced metal availabilityat a higher pH. Sludge amendment enhanced the dry weight yieldof B. chinensis and the increase was more obvious for thesoil with lime treatment. The industrial sludge caused a loweryield than that of the domestic sludge amendment and asignificant reduction in yield at high application rates of YuenLong sludge was also noted. Tissue heavy metal contents, exceptfor Fe, increased as the sludge amendment rate increased whileplant grown in Yuen Long sludge amended soil contained higher Crand Zn contents at each sludge application rate. Liming the soilreduced the heavy metal contents in the plant tissues, exceptfor Fe, which were all below the allowable levels for vegetablecrops. The present experiment demonstrates that liming wasimportant in facilitating the growth of B. chinensis in sludge amended soil. The optimal sludge amendment rate for thesoil with lime amendment was 25% Tai Po sludge and 10% YuenLong sludge, while for the soil without lime amendment was 10% and5%, respectively.

Effect of sewage sludge amendment on soil microbial activity and nutrient mineralization

Abstract An incubation experiment was performed to study the effect of sewage sludge on microbial respiration and nutrient mineralization in a sandy soil as an indication of its effects on soil biological properties and nutrient transformation. Sewage sludge was amended with a sandy soil at 0, 25, 50, 150 and 350 g kg −1 fresh weight. An increase in the sludge amendment rate caused an increase in both pH and electrical conductivity (EC). However, pH decreased while EC increased and then decreased along the incubation time. Nevertheless salinity and heavy metal contents of the soil sludge mixture were all within the safety guidelines. Soluble NH 4 + , NO 3 2− and PO 3 2− increased after amending the soil with sewage sludge, but increasing the application rate to 350 g kg −1 of sludge decreased the N and P mineralization efficiency and created an adverse effect on nitrification. The daily CO 2 evolution pattern was the same in all treatments that CO 2 evolution increased initially and then decreased till the end of the incubation period. All the treatments had peak CO 2 evolution at day 7, except for the soil amended with 350 g kg −1 of sludge which had peak CO 2 evolution at day 2. Similarly, the percentage of C-mineralization decreased with an increase in sludge amendment rate. The present experiment indicated that an application rate of 50–150 g kg −1 sludge for sandy soil would have the optimal beneficial effect on the soil in terms of microbial activity and nutrient transformation.

Impact of climate change on the domestic indoor environment and associated health risks in the UK

There is growing evidence that projected climate change has the potential to significantly affect public health. In the UK, much of this impact is likely to arise by amplifying existing risks related to heat exposure, flooding, and chemical and biological contamination in buildings. Identifying the health effects of climate change on the indoor environment, and risks and opportunities related to climate change adaptation and mitigation, can help protect public health. We explored a range of health risks in the domestic indoor environment related to climate change, as well as the potential health benefits and unintended harmful effects of climate change mitigation and adaptation policies in the UK housing sector. We reviewed relevant scientific literature, focusing on housing-related health effects in the UK likely to arise through either direct or indirect mechanisms of climate change or mitigation and adaptation measures in the built environment. We considered the following categories of effect: (i) indoor temperatures, (ii) indoor air quality, (iii) indoor allergens and infections, and (iv) flood damage and water contamination. Climate change may exacerbate health risks and inequalities across these categories and in a variety of ways, if adequate adaptation measures are not taken. Certain changes to the indoor environment can affect indoor air quality or promote the growth and propagation of pathogenic organisms. Measures aimed at reducing greenhouse gas emissions have the potential for ancillary public health benefits including reductions in health burdens related heat and cold, indoor exposure to air pollution derived from outdoor sources, and mould growth. However, increasing airtightness of dwellings in pursuit of energy efficiency could also have negative effects by increasing concentrations of pollutants (such as PM2.5, CO and radon) derived from indoor or ground sources, and biological contamination. These effects can largely be ameliorated by mechanical ventilation with heat recovery (MVHR) and air filtration, where such solution is feasible and when the system is properly installed, operated and maintained. Groups at high risk of these adverse health effects include the elderly (especially those living on their own), individuals with pre-existing illnesses, people living in overcrowded accommodation, and the socioeconomically deprived. A better understanding of how current and emerging building infrastructure design, construction, and materials may affect health in the context of climate change and mitigation and adaptation measures is needed in the UK and other high income countries. Long-term, energy efficient building design interventions, ensuring adequate ventilation, need to be promoted.

Enzyme Activities in a Sandy Soil Amended with Sewage Sludge and Coal Fly Ash

Previous studies showed that coal fly ash could stabilize sewage sludge by reducing metal availability, but fly ash may cause an adverse effect on soil microbial activities. Therefore, an experiment was performed to evaluate the effects of amendment of soil with anaerobically digested dewatered sewage sludge, stabilised with alkaline coal fly ash, on soil enzyme activity and the implications for soil nutrient cycling. Sewage sludge was amended with 0, 5, 10, 35 and 50% w/w of fly ash, and then the ash-sludge mixtures were incubated with a sandy soil at 1:1 (v/v). Dehydrogenase activity decreased with an increase in fly ash amendment level and the time of incubation. Soil receiving 5% ash-sludge amendment had a higher dehydrogenase activity than other treatments. Soil receiving 10% ash-sludge mixture had the highest urease activity and in general, urease activity decreased with increasing incubation time. Phosphatase activity was the highest at 5% ash-sludge mixture amended soil and no general trend was observed with time. Water-soluble Zn, Mn and Cu contents were suppressed by the addition of fly ash. The present experiment indicated that addition of 10% ash-sludge mixture should have a positive benefit on the activity of soil microorganisms, N and P nutrient cycling, and reduce the availability of heavy metals.

Flood management: prediction of microbial contamination in large-scale floods in urban environments.

With a changing climate and increased urbanisation, the occurrence and the impact of flooding is expected to increase significantly. Floods can bring pathogens into homes and cause lingering damp and microbial growth in buildings, with the level of growth and persistence dependent on the volume and chemical and biological content of the flood water, the properties of the contaminating microbes, and the surrounding environmental conditions, including the restoration time and methods, the heat and moisture transport properties of the envelope design, and the ability of the construction material to sustain the microbial growth. The public health risk will depend on the interaction of these complex processes and the vulnerability and susceptibility of occupants in the affected areas. After the 2007 floods in the UK, the Pitt review noted that there is lack of relevant scientific evidence and consistency with regard to the management and treatment of flooded homes, which not only put the local population at risk but also caused unnecessary delays in the restoration effort. Understanding the drying behaviour of flooded buildings in the UK building stock under different scenarios, and the ability of microbial contaminants to grow, persist, and produce toxins within these buildings can help inform recovery efforts. To contribute to future flood management, this paper proposes the use of building simulations and biological models to predict the risk of microbial contamination in typical UK buildings. We review the state of the art with regard to biological contamination following flooding, relevant building simulation, simulation-linked microbial modelling, and current practical considerations in flood remediation. Using the city of London as an example, a methodology is proposed that uses GIS as a platform to integrate drying models and microbial risk models with the local building stock and flood models. The integrated tool will help local governments, health authorities, insurance companies and residents to better understand, prepare for and manage a large-scale flood in urban environments.