First in a series
It tops the U.N. Environment Program’s most-wanted list. It is a persistent, poisonous chemical with problems transcending borders.
Dioxin is the name for a family of chemicals with a similar basic structure and varying toxicities, the most toxic of which, 2,3,7,8-TCDD, is the most powerful poison known to man. It has been shown to cause cancer, sexual irregularities and impair development in lab animals and is suspected of wreaking the same havoc on humans.
Dioxin exists and persists in low levels nearly everywhere but has been found in relatively high levels in the air in Japan — especially near big cities.
Mostly an unintended byproduct of waste incineration and certain industrial processes, industrial accidents involving dioxin have plagued many countries, and many have taken steps to stem dioxin creation and emission.
Now Japan has taken notice.
A TV Asahi news report on Feb. 1 alleged that high levels of dioxin — .64 to 3.8 picograms — had been found in “leafy vegetables” grown near Tokorozawa, Saitama Prefecture. There was an implication that spinach was among the leafy vegetables.
Demand for locally grown agricultural goods dropped drastically after the show’s airing, forcing politicians to react and the central and prefectural governments to conduct emergency surveys of the Tokorozawa area.
The news report was later clarified Feb. 9 when the broadcaster said the levels found in spinach were between .63 and .75.
But the original broadcast had already set off a chain reaction. Prime Minister Keizo Obuchi established a council of 13 Cabinet ministers on Feb. 24 to shape the nation’s dioxin policies. It marked the first time dioxin had been addressed at such a high level.
And the collaborative survey of dioxin contamination in and around Tokorozawa by the Environment Agency and the ministries of Health and Welfare and Agriculture, Forestry and Fisheries marked the first time several ministries and agencies jointly took part in an area-specific dioxin contamination study.
The results of the study, which focused on spinach, tea, air, water and farm soil in and around Tokorozawa, were released March 25 and showed levels within the range of prior studies and “not high enough to impact human health.”
Nonetheless, the episode fanned fears of the chemical, highlighted the nation’s lagging efforts to curb it and sent the government into full-fledged policymaking mode.
Japan first addressed dioxin in 1996, when the Health Ministry finally set a tolerable daily intake limit — the amount that can ostensibly be ingested without harm to one’s health — at 10 picograms per kilogram of body weight per day. A picogram is a trillionth of a gram.
“This (timing) was a little later than that in other countries,” said dioxin expert Hideaki Miyata, a professor of pharmacology at Osaka’s Setsunan University. “Other nations established TDIs in the late 1980s or early 1990s.”
Miyata attributes Japan’s tardiness to the nation’s high dependence on incinerators and lack of appreciation for the health threat they pose to humans.
But the government now seems to be looking to make up for lost time.
In its third meeting at the end of March, the Cabinet-level council approved guidelines to steer national dioxin policy. They set an ambitious target of reducing dioxin emissions by nearly 90 percent compared with 1997 levels by 2002.
They also commit the government to including coplanar polychlorinated biphenyls (coplanar PCBs) — a chemical closely related to dioxin — and re-evaluating the TDI figure by the end of June.
Some sources within the ruling Liberal Democratic Party, however, say the re-evaluation may come by late this month.
Both the Health Ministry’s TDI of 10 picograms and the Environment Agency’s tolerance level of 5 picograms are to be synchronized and reduced.
In light of increasing evidence that dioxin is more than a carcinogen and that it may affect the immune system and hormone functions of people in lower doses and in ways unimaginable until a few years ago, the World Health Organization last May scaled down its TDI to a range of 1 to 4 picograms — 1 being the ultimate goal and 4 the acceptable upper limit.
Domestically, two opposition parties have already drafted legislation to reduce dioxin and are currently in talks with the LDP, which has been hesitant to embrace some of the wording in the bills.
The LDP opposes giving citizens the right to request government dioxin surveys, the setting of dioxin food standards and a proposed compensation system because of what it calls “the difficulties” involved.
“TDI is going to be the biggest sticking point” in seeking agreement with the LDP, predicted Masahiro Tabata, head of New Komeito’s environmental policy council. Earlier this year, his party submitted a bill to the Upper House to create a law to regulate dioxin.
Preceding the most recent Tokorozawa dioxin hullabaloo and the central and local government’s joint study, the Democratic Party of Japan, the largest opposition group, submitted its own bill to the Upper House.
“Essentially, we feel that dioxin is such a toxic chemical that the government needs to address it specifically,” Tabata said.
When the government establishes a new TDI it will become the foundation for setting tolerable levels in the air, water, soil and sediment. The number must be realistic, but at the same time stringent enough to drive change.
Until now, the government has addressed dioxin in a fragmented way by relying on established laws, such as the Air Pollution Control Law and Water Pollution Prevention Law, Tabata said. Under the bills proposed by New Komeito, dioxin would be addressed in one law, he said.
Both The DPJ and New Komeito bills propose dropping the TDI of dioxin to 1 picogram and setting environmental standards to achieve this stringent level.
Experts estimate that the average person living in urban areas ingests around 2.5 to 3.72 picograms of dioxin per day, with 70 percent to 90 percent of the figure coming from fish, meat, eggs and dairy products.
But the LDP nixed the 1 picogram figure, and instead the three parties are poised to agree on the wording of “4 picograms or less,” and will leave the setting of a precise figure up to the Environment Agency and the Health Ministry.
Differences still remain, and the three parties have continued to work behind closed doors to iron them out. If all goes well, an amended version of New Komeito’s bill may be approved during the current Diet session.
However, some LDP officials warn against excessive expectations. “Passage during this session is possible, but not probable,” said Nobuhiko Igarashi, a secretary for Tsuneo Suzuki, director of the LDP’s Policy Research Council’s environment division.
These differences will likely be resolved, but probably not before June 17, the end of the regular Diet session, he said.
If passed, the legislation would place Japan near the head of the class in terms of dioxin regulation among advanced countries. But whether the nation can deliver on realizing major dioxin reductions remains to be seen.