Journal of Japan Society for Safety Engineering

It　is　known　that　zirconium　cydride　（ZrHx，　0くx＜＝2）reacts　with　oxygen　in　air　to　ignite　and　deflagrate　like　zirconium．Energy　of 50％ ignition　is　effected　by　the　sample　volume　and　air　content　in　it　as　well　as　hydrogen　content，x．It　was　observed the　energy　of 50％ ignition　decreased　with　Iower　hydrogen　content　and　with　smaller　gap　length　in　zirconium　hydride．In mixtures　of　zirconium　hydride　and　oxidants，the　energy　of 50％ ignition　deereased　with　the　lower　hydrogen　content　and　was lowest　with100％zirconium　hydride　colltent．In　a　stoichiometric　mixture　of　zirconium　hydride　and　oxidant，the　energy　of 50％ ignition　showed　to　decrease　and　to　be　effected　by　capacitance　of　condencer，hydrogen　content　of　Zirconium　hydride，type　of　oxidants　used，and　particie　size　of　oxidant．In　the　mixtures　containing 80 to 95％ zirconium　hydride, oxidant works like　dilute，and　starting　voltage　of　discharge　is　changed　so　that　energy　of 50％ ignition　increases　abnormally.

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It　is　well　known　that　the　mercury　in　hair　of　people　eating　fishes　is　comparatively　high　concelltrations．111recent　years，elevated　mercury　concentrations　have　been　reported　in fish　on　foreign　comtries、Although　the　amount　offish　consumption is　still increasing，the　action　level　of　big fish　such　as　tuna　with　mercury　levels　exceeding　state　health　standards　is　non regulation　in　Japan、Therefore，current　mercury　intake　from　foods　in Japanese　people　is　unknown. The　purpose　of　this investigation　was　to　estimate　the　mercury　intake　from　environment．Foods　available　in　the　market　were　used　as　samples for　mercury　investigation．Total　mercury　from　foods，eatable　base，was　the　intake　of　O.15mg　per　week　Approximative 100％ of　mercury　intake　from　environment.　resulted　from　fish　eating．According　to　the　hypothesis　that 75％ of　total　mercury　is methylmercury，the　weekly　intake　of　O.11mg　as　methylmercury　was　corresponding　amount　to　about 62％ of　provisionaI tolerable　weekly　intake　O．／7mg　di丘ned　by　the　Welfare　Ministry

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