The numbers are rising, wildlife is crossing boundaries, and viruses are touching children’s hands. None of these are stories of ‘someone dying today.’ This is precisely why, without a mechanism to make these risks visible, it may be too late by the time we realize them.

In Asaminami Ward, Hiroshima City, at Asa Zoological Park, and in the jurisdiction of Fukuyama City Health Center—three different types of risks surfaced simultaneously from the end of June to July in Hiroshima Prefecture. These include groundwater contamination by PFAS (per- and polyfluoroalkyl substances), the appearance of wild Asian black bears within the zoo grounds, and an alert for hand, foot, and mouth disease. While none of these pose an immediate threat to life, they share a common structure: the issue of who visualizes these risks and how they are communicated.

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PFAS—The Significance of the Increase from 10 to 13 Houses

In Asaminami Ward, Hiroshima City, the number of residences where PFAS was detected in drinking groundwater—exceeding the national provisional guideline value (50 nanograms per liter for the sum of PFOS and PFOA)—has increased from 10 to 13. At first glance, this merely appears to be an increase of three houses. However, the significance of these three houses is not trivial.

PFAS is a collective term for organic fluorinated compounds used in a wide range of applications, including foam fire extinguishers, water-repellent treatments, and semiconductor manufacturing, due to their water- and oil-repellent properties. They are known as ‘forever chemicals’ because they do not break down in the environment. Accumulation in the body has been internationally linked to decreased immune function and increased cancer risk. However, symptoms do not appear the day after consumption; it can take years for effects to manifest—this is why they are ‘invisible.’

The increase from 10 to 13 houses indicates a possible expansion of the contamination area beyond initial assumptions. Groundwater flows independently of surface boundaries. The location of wells, the direction of aquifers, and the permeability of geological formations all influence the spread of contamination, making it difficult for authorities to predict ‘where next’ even when investigations are conducted at the household level. The city has requested residents to cease drinking from affected wells and is expanding water quality investigations, but has not yet identified the source of contamination.

The question here is, ‘What comes after the request to stop drinking?’ Securing alternative water sources, covering the costs of switching to municipal water, and establishing a long-term health monitoring system—if residents can take the action of ‘not drinking,’ what mechanisms are in place to support their lives afterward? While it is appropriate for the authorities to announce the fact that the numbers exceed guideline values, the announcement is not the goal but the starting point. Only when the residents of the 13 houses can concretely envision ‘what to do next’ can we say that visualization has functioned.

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Asian Black Bears—When Boundaries Become Unstable

A wild Asian black bear was captured on camera within the grounds of Asa Zoological Park. The zoo has closed certain areas to ensure safety and is alerting visitors.

The essence of a zoo lies in ‘drawing a clear boundary between wildlife and humans.’ Cages and fences serve as physical barriers while also providing a psychological safety zone for visitors, indicating ‘beyond this point is a managed space.’ The intrusion of an unmanaged wild bear into this area is not merely a case of ‘bear sightings’ but an event where the boundary itself has become unstable.

This is set against the backdrop of an increasing trend in bear sightings and encounters in Hiroshima Prefecture in recent years. Factors such as depopulation in rural areas, the expansion of abandoned farmland, and fluctuations in the availability of food sources like nuts have combined to bring bear habitats closer to human living spaces. Asa Zoological Park is located at the boundary between urban areas and mountainous regions, where wildlife does not recognize ‘boundaries’ in the first place. The lines drawn by humans are unknown to the bears.

The zoo’s response—monitoring through cameras, area closures, and collaboration with relevant agencies—seems like a reasonable decision based on limited information. However, the question remains about ‘what comes next.’ How long will the closures last? Will bears be captured or driven away? How will the zoo’s structure be reassessed to prevent future occurrences? For visitors, especially families with children, a sign indicating ‘some areas closed’ does not provide enough information for decision-making. Why are the areas closed? What level of risk is involved? Is there a timeline for reopening? Only when this information is conveyed can it transform into a judgment of ‘safety’ or ‘caution.’

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Hand, Foot and Mouth Disease—How to Convey the ‘Temperature’ of Alerts

Hiroshima Prefecture issued an alert after the number of reported cases of hand, foot, and mouth disease exceeded the alert threshold (5.0 cases per monitoring site) in the jurisdiction of Fukuyama City Health Center. Hand, foot, and mouth disease is an infection caused by enteroviruses, primarily affecting children under five years old. It is characterized by vesicular rashes in the mouth and on the hands and feet, and most cases recover naturally within about a week.

‘Usually mild’—this phrase tends to overshadow the seriousness of hand, foot, and mouth disease. In reality, there are rare cases where complications such as meningitis or encephalitis occur, and hospitalizations due to dehydration are not uncommon. Infants, in particular, may refuse to eat or drink due to pain in their mouths, rapidly depleting their strength. For parents, there exists an insurmountable gap between the statistical fact that ‘most cases are mild’ and the sight of their child crying in distress.

The alert system automatically activates when numbers exceed the threshold. This is a rational system design that eliminates subjectivity. However, how much the fact that ‘an alert has been issued’ changes parental behavior depends on how the information is delivered. Notifications through daycare centers and kindergartens, municipal websites, and social media—there are multiple channels for information, but whether they lead to ‘what should we do for our child right now’ in terms of specific action guidelines significantly affects the effectiveness of the alert. Thorough handwashing, avoiding sharing towels, and refraining from sending children to daycare if rashes appear—these specific measures become the circuit connecting the abstract signal of the alert to daily life at home.

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Common Structures Among the Three Risks

PFAS, bears, and hand, foot, and mouth disease. The subjects are entirely different—substances, animals, and viruses. However, when these three events are lined up, a common structure emerges.

First, they are all risks that do not lead to immediate death. The health impacts of PFAS accumulate over years, encounters with bears are a matter of probability, and most cases of hand, foot, and mouth disease are mild. Because they do not lead to immediate death, the priority for response tends to decrease. However, the characteristic of this type of risk is that a lower priority can lead to delayed responses and expanded damage.

Second, it is difficult to see ‘who the stakeholders are.’ PFAS contamination may seem like an issue only for households using well water, but groundwater flows across administrative boundaries. Bear sightings may seem like a zoo issue, but they overlap with the living spaces of surrounding residents. Hand, foot, and mouth disease may appear to be a children’s illness, but it affects the employment of caregivers, the operation of daycare centers, and the regional healthcare system. The more blurred the contours of the stakeholders become, the more a void is created with the assumption that ‘someone will take care of it.’

Third, the mechanism of visualization tends to stop at ‘announcement.’ The city announces the numbers. The zoo notifies of area closures. The prefecture issues alerts. All of these are correct initial responses. However, it requires another level of translation for the announced information to be transformed into specific actions by residents. The circuit that turns numbers into ‘personal matters’—this cannot be solely shouldered by the administration. Healthcare providers, educators, local media, and dialogue among residents support this translation.

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Who Visualizes ‘Invisible Risks’?

The administration provides the numbers. Experts add interpretations. The media provides context. Residents judge based on their own lives. If any link in this chain breaks, the risk remains in a state of ‘known but not felt.’

The three events that surfaced simultaneously in Hiroshima Prefecture are processed by different departments, different experts, and different response flows. This is naturally part of administrative division of labor. However, from the residents’ perspective, questions such as ‘Is the water in Asaminami Ward safe?’ ‘Is it okay to take my child to the zoo?’ ‘Can I leave my child at daycare?’ all arise within the same day. Risks are managed in silos, but daily life is not.

This is why a perspective that looks across different risks and continually asks, ‘Who does this make easier?’ is necessary. It is about translating risks along the lines of the lives of those receiving the information, rather than the logic of those providing it. That is the true meaning of ‘visualization.’

The 13 wells, one bear, and the number of cases per monitoring site—behind these numbers are hands turning on faucets, hands holding children’s hands, and hands checking foreheads for fever. The question is whether we can prepare the words that reach those hands as a system. This summer in Hiroshima quietly poses that question.