Japan's Approach to the Reduction of Unintended Contamination of By-product Hexachlorobenzene (HCB)

It was recently identified in Japan that Hexachlorobenzene (HCB) was unintentionally contained as by-product at a significant level in certain chemical substances such as Tetrachlorophtalic anhydride (TCPA, CAS No.117-08-8) and its derivatives (e.g. Solvent Red 135, CAS No.20749-68-2).

HCB is to be eliminated globally based on the Stockholm Convention* and is designated in Japan as one of the Class I Specified Chemicals of which production, import and use are prohibited under the Chemical Substances Control Law. Since it is important to reduce the contaminant HCB, the Class I Specified Chemical, as a by-product in other chemical substances as much as possible, the Law requires its reduction by applying the BAT (Best Available Technology/Techniques) for preventing its generation.

In April 2006, the MHLW, METI and MOE established an "Assessment Committee on the BAT Levels for Reduction of a Specified Chemical as a Contaminant By-product" to evaluate the technically and economically best feasible level (BAT level) for reduction of by-product HCB. In addition, the three Ministries required manufactures and importers of TCPA and other substances to take their best measures to reduce the contaminant HCB in these products as well as to manage and report the status of their production, import, sales and storage.

The Committee had conducted hearings with producers and importers of TCPA and Solvent Red 135 to evaluate the BAT for reducing HCB. In August 2006, the three Ministries published the draft report of the Committee and invited public comments on it. Taking the comments into consideration, the Committee finalized its report on November 9, 2006, which proposed the BAT levels for reduction of by-product HCB in these chemicals (200ppm for TCPA and 10ppm for Solvent Red 135).

The three Ministries are going to require manufacturers and importers of these chemicals to make their further efforts for reducing by-product HCB in accordance with this report. Furthermore, the three ministries and the Committee has just started to evaluate other chemical substances including by-product HCB such as Phthalocyanine derivatives (e.g. Pigment Green 7 (CAS No.1328-53-6) and Pigment Green 36 (CAS No.14302-13-7)) and several TCPA derivatives other than Solvent Red 135.

* Stockholm Convention on Persistent Organic Pollutants

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