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are pcb's dangerous ?

Discussion in 'Electronic Basics' started by programmerforhire, Nov 13, 2003.

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  1. Has anyone heard the news item about the ships which were sent
    from the u.s. to the u.k. for decomission and cause some pretest
    due to the fact that it contains 'asbestos and pcb`s '.
    I new asbestos was dangerous, but since when are pcb's
    dangerous, or is there some other kind of chemical with the same
    name ?
    rex.
     
  2. James Beck

    James Beck Guest

    Yes PCB is a chemical.
    PCB = poly-chlorinated biphenyls

    Nasty stuff.

    Do a web search.

    Jim
     
  3. Polychlorinated Biphenyls (PCBs) (sorry for the wrap)

    http://environment.about.com/gi/dynamic/offsite.htm?site=http:/%
    2Fwww.atsdr.cdc.gov%2Ftoxprofiles%2Fphs17.html
     
  4. Don Bruder

    Don Bruder Guest

    "PCB" in this particular case equals "(P)oly(C)hlorinated(B)iphenyls" -
    Some *SEVERELY* nasty toxic crap that, before we figured out it was bad
    news, was heavily used in a lot of things like high-voltage transformer
    and capacitor oils. Once it was figured out how bad it actually is to
    have anywhere near anything that remotely resembles "alive", it was
    outright banned in many countries.

    About that time, disposal of the stuff was changed from the usual "Well
    duh... just dump it someplace" to "OK, you say you've got a pint of
    PCB-tainted oil? No problem. You just need to fill out these 87 pages of
    forms, in triplicate, twice, staple one set to your forehead, tape
    another to the jar, mail one set to the EPA, file the fourth set for the
    next 23 years, deposit a 5th set with your local hazardous wate board,
    and keep the 6th set in your hand at all times until the stuff is gone.
    Once you've completed that, you're required to build or rent a 37
    million dollar airtight incinerator that allows nothing but CO2 and
    water to escape, hire 39 legal consultants, buy 14 billion dollars worth
    of liability insurance, pay the wages of 19 EPA advisors, sumbit to and
    pay for weekly groundwater tests to be conducted randomly at sites
    located anywhere within a 40 mile radius of the location where the
    container of waste oil is stored, pay for any cleanup of any detected
    residue, and live with an EPA inspector grafted to your hip for the next
    10 years. Only THEN may you file an application for a permit to dispose
    of the stuff."

    And the worst part is, the stuff actually IS bad enough to warrant such
    overkill :(
     
  5. so why do these ships contain this chemical, what do they do with it ?
     
  6. James Beck

    James Beck Guest

    Probably in some of the power transformers and anywhere else a
    dielectric oil was used for cooling.

    The best way to get rid of it is to burn it. Supposibly it renders it
    harmless. I know locally it has been blended with fuel oil and used to
    heat road asphalt.


    Jim
     
  7. thanks, and thanks to keith for the very very useful link.

    Igonorance Is A Handicap
     
  8. PCBs stands for polychlorinated biphenyls. I forget the name of the
    movie but Ron Howard starred in it, about a farmer that had to kill
    all his cattle because the cattle feed was polluted with PCBs. The
    stuff has been banned for a long time, but it was used in oil cooled
    transformers and other electrical equipment, and so is still around in
    many places. Locally, a transformer on a power pole blew out and
    splattered the stuff all over the people's lawm. Because of the PCBs,
    the fire dept had to scoop up and dispose of all the grass and dirt
    around the pole. It gets into your body and causes all sorts of
    problems.

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  9. According to the URL given in the other followup,
    http://environment.about.com/gi/dynamic/offsite.htm?site=http://
    www.atsdr.cdc.gov%2Ftoxprofiles%2Fphs17.html
    It's not so much how bad it is, but how persistent it is in the
    environment. Like other compounds containing clhorine, it breaks down
    very slowly and the amount in the enviromnent has been building up
    steadily. Like it says, everyone in industrialized countries has some
    of it in their bodies. And like is says, it's probably carcinogenic,
    but there are other things far worse. since they are similar to
    hormones, they cause some strange effects in the body. I didn't say
    they weren't bad, I am saying that they're already there, so you can't
    do much about it to get rid of them. Except die. :p




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    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
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  10. Don Bruder

    Don Bruder Guest

    BZZZZZZTTTTTTTT!!!!!!!

    Sorry, Watty, old bean, but that's an incorrect response.

    That movie you mention (whose title I also can't recall... "Bitter
    Harvest" is coming to mind, but I'd bet that's *WAY* wrong) was about
    the mid-to-late 70's incident where a bulk-truck that was supposed to be
    loaded with vitamin and mineral supplement for use in mixing animal feed
    somehow (to this day, I haven't heard a coherent explanation for it) got
    loaded with *PBB* - Polybrominated Bipheynl - a flame-retardent that's a
    close chemical cousin of PCB, and was (then) frequently used on kids'
    pajamas, furniture, and draperies, among other things - and then got
    dumped into the Michigan Farm Bureau's main supply bunk, where it got
    stirred into cattle and chicken feed, most of which got shipped out and
    used across the state (and to a much lesser extent, into Wisconsin and
    Ohio) before anyone had any idea anything was wrong.

    The resulting mess essentially wiped out Michigan's beef and dairy
    industry, and had a severe impact on poultry as well.

    I remember it well... I grew up in Northern Michigan, and it's hard to
    forget the images (seen over and over on the TV news every night, later,
    in the movie which you're talking about, and first-hand with my own
    glassy little peepers) of farmers watching Michigan National Guard units
    digging trenches in their fields, herding what was left of their stock
    into them, then gassing or machine-gunning them by the hundreds and
    filling in the hole. And I'll cheerfully call *ANYONE* who wants to
    claim that such things didn't happen a liar to their face... I watched
    it happen with my own two eyes just outside Petoskey. And Traverse City.
    And Charlevoix. And I have *NO DOUBT WHATSOEVER* that similar scenes
    could be found happening all over the state during those days. More than
    one of those farmers sucked off a shotgun afterwards, unable to live
    with the fact that their entire life's work, and in some cases, several
    generations worth of family effort, had to be destroyed due to
    somebody's screwup at a feed mill they'd never even laid eyes on, and
    wouldn't have recognized if they'd been taken on a guided tour.
     
  11. Terry

    Terry Guest

    AFIK the burning of PCBs has to be above certain temperature in
    order to safely destroy the chemical. PCBs were used I believe
    because they enhanced the heat dissipation characteristics of the
    oil used in power transformers etc. There was quite a fuss in
    Canada about disposing of it safely.
    Some abandoned DEW Distant Early Warning radar sites up north and
    other scrapped Cold War defence installations were found to have
    excessive amounts of such substances as PCBs etc. the long term
    dangers (cancer causing for PCBs?) were not known or acknowledged
    back then!
     
  12. Don Kelly

    Don Kelly Guest

    ---------
    PCB's got a bad name originally because they were present in a situation in
    Japan, way back when. However what did not hit the news was that in that
    case there were known carcinogens present. The bad name persisted. However,
    as it now stands, the PCB's have been cleared (?) of this but are presumed
    to be a factor in other nasty effects. Note that many linemen used PCB oils
    to clean their hands after doing dirty work- there seems to be no record of
    adverse effects. They are a poor substitute for salad oils - taste isn't
    good but the harm of ingestion is questionable.

    PCB's can be destroyed by burning- at a high enough temperature and there is
    a facility in Alberta, Canada which can do this. Simly throwing it in the
    fire may cause problems due to breakdown products which might be nasty.
    My own opinion, right or wrong, is that PCB's have a lot worse press than
    they deserve. We have a lot worse stuff around that we ignore.
     
  13. I remember seeing trucks spraying used transformer oil on the dirt
    roads in Ohio state parks in the late '60s and early '70s. I was told
    the electric companies "donated" the used oil to the state, and I always
    wondered if it was tested for PCBs before it was sprayed all over the
    place.
     
  14. Fred Abse

    Fred Abse Guest

    AIUI, that's the problem. Burning at too low a temperature releases
    combustion products (dioxins, etc.) that are more toxic than the PCBs
    themselves. ISTR that there is an office building somewhere that had a
    substation fire in the basement, and the PCB combustion products got into
    the ventilation system. The building had to be sealed, and will probably
    remain so for a long time.
     

  15. PCB's were used originally because they resited high voltages well and
    have a good dielectricity constant (meaning you can build capacitors
    with high capacitance values, high voltage specification and small foot
    prints). Also they are fire retardant, so can be used in equipment that
    gets hot (TV sets, power transformers and the like).

    They also have low *acute* toxicity, so they did not red-flag with the
    safety tests in use in the 50s and 60s.

    Unfortunately they have a couple of properties that make them a very big
    pain very low down in the neck: They are highly carcinogenic, live
    almost for ever once released into the environment (accumulating an
    adipose tissue and mothers milk) and upon improper incineration create a
    compound with the ominous name Tetrachlorodibenzodioxine, considered one
    of the most toxic compounds known to man (known to lay persons as
    "Seveso-poisson", after a city in Italy that got polluted with the stuff
    when a chemical plant blew up some 30 years back). As a general rule,
    any organic compound containing chlorine or bromine is bad news indeed
    for the environment.

    For those reasons the use of this material was banned many years ago,
    but it can still be found in old equipment (like the ships the OP
    mentioned). Those equipment need to be carefully dismanteled, the PCBs
    removed and then incinerated in specialised plants with appropriate
    scrubbers, a hugely expensive process.

    As far is I understand from the news (but nowbody seems to quite
    understand this dark-of-the-night operation), some company in England
    offered to dismantle the ships for a much lower price than would have
    been possible in the US. Apparently, they did not have permission to
    handle such materials however, and wanted to use cheap (=inadequate)
    procedures for disposal.

    Old rule for making a quick buck: privatise profits, then socialise
    costs (the cleanup required later).

    The use of materials now known to be very dangerous for hand cleaning is
    unfortunately no joke, I still remember benzene being used exactly for
    this purpose in the lab.
     
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