The goal of my Summer Institute (SI) research in Japan was to explore the feasibility of using algae as an alternative indicator of water contamination by gastrointestinal (GI) disease pathogens.  I formulated this goal based upon (1) my perceptions of the magnitude of GI diseases on global morbidity and mortality, and (2) my commitment to identifying practical environmental health solutions.  

In Japan, I was able to fulfill this goal and witness several other environmental health projects.  Although the ensuing report focuses on my studies of algal bioindicators of GI pathogens in water, it also describes what I learned regarding (1) lead in household water pipes, (2) nanofiltration for remote water purification, (3) disinfection byproducts and endocrine disrupters in water, (4) water supply infrastructure, research, and response to public health threats, and (5) ecology, plant biology, environmental design and health

Worldwide, GI diseases are the second leading cause of death after cardiovascular disease. Further, their prevalence may be increasing due to habitat change and microbial evolution. Although GI diseases particularly prevail in developing countries with precarious sanitation and mitigation systems, they are ubiquitous and universal agents of illness, transcending nation-state boundaries and affecting populations in all pockets of the world. Because conventional monitoring methods are not procedurally and financially feasible for many resource-challenged areas, my goal was to investigate alternative methods for detecting water supply contamination.

Specifically, I sought to examine algae as a bioindicator of GI pathogen presence, as it naturally coexists in the water environments from which we draw our drinking water. I chose to conduct my studies in Japan due to existing infrastructure and expertise at the National Institute of Public Health in Tokyo. I participated in this study under the direction of Dr. Han-Seung Kim, Ms. Sugimoto, and Dr. Michihiro Akiba.

We focused on Cryptosporidium, a protozoal GI pathogen that has been responsible for numerous acute public health outbreaks in Japan, the US, and elsewhere around the world. Contamination of water sources by Cryptosporidium oocysts has been a problem for water suppliers globally because this parasite is resistant to chlorine, the typical disinfection agent used in water treatment facilities around the world. Successful removal of Cryptosporidium likely indicates effective water treatment, as other pathogens are typically easier to remove. However, direct monitoring of Cryptosporidium is difficult because it is time consuming and studies on Cryptosporidium itself have been limited by its health risk.

NIPH’s experimental model of water purification involved a series of tanks, pipes, stirrers, and flocculators (Fig 2). To simulate actual water treatment the coagulant poly-aluminum chloride was used and artificial turbidity was induced using Kaolin solution. pH was fixed at 7.0 using NaOH and HCl, and alkalinity was controlled using NaHCO3 solution. Samples were taken at fixed time intervals during 150 minutes and were evaluated for particle count and microscopy for Cryptosporidium and/or Scenedesmus.

To adequately analyze relative removal rates under fluctuating turbidity and pathogen concentration levels, as might be present in natural waters, the residual presence of organism (Cryptosporidium or Scenedesmus) was evaluated in each of four scenarios:

At the time of this writing, the data were still being processed in Tokyo and are therefore not here discussed. However, gross examination of the raw data shows that Cryptosporidium is consistently easier to remove by the coagulation and filtration process than Scenedesmus. Hence, the removal performance of Cryptosporidium can be evaluated by monitoring the removal rate of our bioindicator Scenedesmus, as hypothesized. This suggests that Scenedesmus is an effective bioindicator of GI pathogens in drinking water sources, in the specific context of Cryptosporidium contamination. These findings have the potential to be a very powerful tool for water health monitoring and management-- especially in resource-limited areas-- as algal populations are more easily monitored than GI pathogens themselves, requiring less expertise and resources.

My goal during these 8 summer weeks was not only to pursue the research study I had proposed, but also to gain a general picture of environmental health research in Japan. I therefore sought to engage with other research groups at the National Institute of Public Health as well as other government, academic, and private institutions around the country. The sections below describe the topical areas that I explored as part of my inquiries and interactions.

My site visits to the Tokyo Metropolitan Government Water Quality Management Center and Tokyo University Department of Urban Engineering, in addition to the activities at my home institution, the National Institute of Public Health (NIPH), demonstrated that lead contamination of drinking water is a significant issue in Japan.  Lead is a toxic metal, causing severe developmental defects in children and neurological deficits in those of all ages.  Traditionally, lead pipes have been used in waterworks around the world, due to its structural soundness.  It has only been in the past several decades that public health and infrastructural campaigns have replaced municipal lead pipes with others made of iron, vinyl, and other materials.  The problem remains within older households, however, as their internal plumbing still consists of lead pipes and is beyond the reach of public works commissions. 

At the (NIPH) I interacted with researchers Dr. Kasuaki Mori and Dr. Toshimitsu Akai in studies of lead dissolution from pipe into flowing water (Fig 3).  Specifically, the studies aimed to delineate how different combinations of pipe materials, lengths, and stagnation times would influence lead concentration in downstream water.  At the Tokyo Metropolitan Government Water Quality Management Center I observed experiments on household water filters that sought to quantify relative lead removal efficiencies. 

Although many think of Japan as a very densely populated country, many regions are sparsely populated and lack complete water purification facilities due to their remote locations and poor infrastructure. As a result, many areas receive water that has only undergone primary treatment and not secondary treatment, a situation that may produce water that is turbid, dirty, unaesthetic, and potentially pathogenic.

Nanofiltration technology could be the answer to this difficult situation. It involves filtering water through very small honeycombed sieves that are specially constructed to remove suspended, colloidal, dissolved, and even ionic solids due to their very small openings (on the scale of nanometers). Nanofiltration can be superior to conventional treatment because it requires far less construction, smaller facilities, and requires no active monitoring by personnel, though the filters must be periodically changed and are expensive.

The United States, France, and Germany have done much experimentation on nanofiltration. Because the efficacy of nanofiltration depends on specific water composition and environmental setting, these results are not directly applicable to Japan. Japanese researchers are not sure what kind of membrane composition (polyamide vs. cellulose acetate vs. ceramic vs. propylene vs. polyethylene) and tube construction (hollow fiber vs. tubular vs. spiral) is suitable for purification of Japan drinking waters. I spent time with an NIPH researcher, Dr. Masaki Itoh, who was comparing the relative efficacies of 14 different filters in removing contaminants of various molecular weights, with a specific focus on ionic materials and dissolved organics.

I took an informal survey while I was in Japan, asking Japanese individuals what they thought was the biggest environmental problem in Japan. The unanimous answer was endocrine-disrupting chemicals. Although we hardly hear about it in the United States, endocrine disrupting chemicals are a real threat in Japanese minds because these industrial and incineration byproducts are currently blamed for changing the gender of certain animals in parts of Japan. The population fears that human beings could be the next victims of such dire consequences.

Endocrine disrupting chemicals (EDCs) generally spread via water. As such, my group at the NIPH has a division focused on chemical analyses of EDCs in drinking water. I interacted with an NIPH research, Dr. Mari Asami, to learn about her work on EDCs as well as other chemical contaminants of drinking water supply. Bromate, an ozonation disinfection byproduct, is of particular concern since it is carcinogenic. The NIPH is testing granular activated carbon and biological activated carbon as bromate removal agents. Pesticides are another significant concern because they have carcinogenic and developmental influences. Dr. Asami and her group are exploring pesticide reactivity in environmental waters and treated (ozonated) drinking water, with the hopes of understanding their dynamics and health effects in our water supply.

To appreciate the full context of water supply provision, environmental response, and public health mitigation in Japan I visited and spoke with executives and managers at several government, academic, and private institutions focused on these goals.

At the Tokyo Metropolitan Government Water Quality Management Center I examined their water quality monitoring and testing stations, and also learned about their active research projects. The most striking aspect  of this visit was hopping onto a bus they had equipped as a miniature laboratory, equipped with billion-yen scientific instruments that could be deployed at a moment’s notice should an environmental catastrophe strike in a distant location or an earthquake debilitate the main laboratory (fig 4). Visiting Tokyo University’s Department of Urban Engineering showed me how academic research in Japan focuses on practical problems with unique academic rigor, while maintaining intimate links and collaborations with government-directed research activities.

While at the NIPH, I also witnessed a real-time public health investigation. A neighboring prefecture, Kanagawa, was experiencing picoplankton (tiny tiny plankton!) in its water supply and was unable to identify the responsible agent. Not knowing the identity of this contaminant caused concern for many public health officials, as some plankton species can produce toxins and cause illness. Samples were sent to our office at the NIPH, where my colleagues immediately jumped on trying to isolate and identify the mysterious agent. When I departed, the plankton had still not yet been identified.

To maximize my learning and exposure to Japanese thought processes, research methods, and implementation techniques in areas other than water and sanitation, I also spent time visiting and working with several researchers in disciplines relevant to my previous work in ecology, biology, and environmental design. I describe them here briefly, as they were not intimately linked to the main thrust of my summer research into water quality and health.

1- Laboratory of Tropical Ecology, National Institute for Environmental Studies, Tsukuba: here I gave a seminar on my previous research on sustainable forest management biology and policy and learned about current attempts to integrate GIS technology into sustainable forest management.

2- Environmental Microbiology Laboratory, National Institute for Environmental Studies, Tsukuba: I spoke with mycologists to learn more about the algae I was studying at NIPH in our GI pathogen research.

3- Division of Forest Science, Osaka City University: I also gave a seminar here on my previous sustainable forest management biology and policy research and learned about current tree composition and ecological changes in the local forests (Quercus to Podocarp) due to increasing deer populations.

4- Tropical Forest Resources and Environments, Kyoto University: I visited a professor who works in the same types of forests in which I used to work in Asia.

5- Center for Ecological Research, Kyoto University: I also gave a seminar here on my previous sustainable forest management biology and policy research

 

　

My summer research and amazing cultural experience would not have been possible without the generous support of the US National Science Foundation, JISTEC, and Japan’s National Institute of Public Health. Special thanks to Dr. Shoichi Kunikane (NIPH), Dr.Masataka Kawai (NIPH), Dr. Han-Seung Kim (NIPH), Dr. Michihiro Akiba (NIPH), Dr. Toshimitsu Akai (NIPH), Dr. Mari Asami (NIPH), Dr. Yamakura (Osaka City University), Ms. Kimiko Kobayashi (JISTEC), Professor Suzuki-san (Tsukuba), Professor PS Ashton (Harvard University), Professor NM Holbrook (Harvard University), Harvard Medical School, everyone at the NSF Tokyo Office, and my colleagues from the SI program. Domo arigato gozaimasu!