EDITORIAL: High soil dioxin levels merit swift action by government

Asahi Shimbun 1998/05/07

After years of media attention to the problem of dioxin contamination of our air and food, a new issue has emerged--contamination of the nation's soil by this deadly toxin.

High levels of dioxin were detected recently in the soil around a waste incinerator in Toyono District, Osaka Prefecture. The levels, in fact, were far higher than anything measured in Japan so far.

The incinerator is believed to be the source of the contamination. Experts point out this incinerator has a structural flaw that makes it prone to incomplete combustion. The burner was also operated at low temperatures that promoted the generation of dioxin, and was poorly maintained as well.

Furthermore, the experts say, because the facility is surrounded by mountains on all sides, emissions tend to become concentrated in the immediate area. However, those factors still don't quite explain why contamination has reached such a high level.

Neither incinerator maker Mitsui Engineering & Shipbuilding Co., nor the local environmental administration cooperative set up by two towns was eager to examine the situation and control the pollution.

They shut the incinerator down only after they got caught neglecting to make their obligatory report to the Health and Welfare Ministry--even though emissions showed a level of dioxin that was more than double the "emergency action required" standard set by the government. The truth came out only after an investigative committee of experts, set up at the insistence of local citizens, conducted an intensive probe.

What is quite unsettling about this case is that it is apparently not unique to this particular locality. About 50 incinerators of the same type are in operation around Japan, and all emit on average more dioxin than allowed under the government's "emergency action required" standard. This means soil contamination is a real possibility everywhere.

One reason why no firm action has been taken is that Japan has no environmental standards for soil contamination.

Where dioxin itself is concerned, various regulatory measures have been introduced or reinforced over the last couple of years. The new rules include setting a "safe level" for daily dioxin intake and prescribing permissible emission levels under air pollution control laws.

But no regulatory standards have been set for soil contamination, on the grounds that soil, unlike air or food, has no immediate effect on human health. And in the absence of any regulatory standards, there are no regulatory measures, needless to say.

That was why the municipalities, residents and the incinerator maker involved in the Toyono case didn't know what to do, even after an abnormally high levels of dioxin had been detected in the soil.

The investigative committee has suggested that 10 to 20 centimeters of topsoil be scraped away and discarded from the heavily-contaminated 30,000-square-meter area. This solution was "borrowed" from what Germany prescribes for soil contamination in residential areas, but Japanese experts admit they are not quite sure if the topsoil depth and the size of the area are adequate for the purpose.

The two municipalities and the environmental administration cooperative are willing to go along with the committee suggestion. However, it will certainly not be easy to find a dumping ground for several hundred truckloads of contaminated soil. In addition, the cost of this operation may be too much of a fiscal burden on those small municipalities. And finally, Japan is totally inexperienced in neutralizing or detoxifying such a massive amount of polluted soil.

But local farmers are already beginning to suffer damages from unfounded rumors to the effect that their produce has been contaminated by dioxin in the soil.

Most experts maintain, however, that dioxin is rarely assimilated into plants from their roots, so that eating them will have no direct effect on health. It is to be strongly hoped that the parties concerned will deal appropriately with any irresponsible rumors that are spread just to scare people. Still, it is a fact that the soil has been contaminated quite heavily. Health checks are a must for local residents, if only to put their fears to rest.

It was only just recently that the Environment Agency announced plans to conduct soil surveys at 40 locations, starting this fiscal year. Now that one case of contamination has been confirmed, albeit only partially, the agency must add a lot more survey points to its list, at least in areas where incinerators of the same type as Toyono's are in operation.

The need for conducting such surveys and setting regulatory standards has been voiced repeatedly in the past. There is no question that the nation's environmental authorities have been grossly negligent in their duties.

They must act before visible damages occur. And they need to put together some comprehensive countermeasures against dioxin pollution as soon as possible, taking into account soil contamination by this deadly substance.