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Medicine Earth Government Science Technology

How Cities Are Using Dry Ice To Kill Rats (usatoday.com) 429

Some of the United States' biggest cities have resorted to using dry ice to kill rats. Since dry ice (frozen carbon dioxide) turns into a gas, sanitation officials simply need to drop chunks of it into rat infested burrows and let science do the rest. Longtime Slashdot reader mi writes: USA Today reports: "Earlier this week, USA TODAY observed Chicago sanitation department workers at one of the city's oldest parks scoop chunks of smoking dry ice into a burrow before quickly covering the entry and exit holes with dirt and newspaper to stop any rats from escaping as the -109.3-degree Fahrenheit gas dissipated. Sanitation workers say they treat burrows during morning hours, when rats are less active and most likely to be huddled inside the burrows. The asphyxiated dead rats then decompose in place and out-of-sight of city denizens who count the disease-carrying vermin among the vilest of indignities of urban living. 'We are seeing 60% fewer burrows in areas where we are using the dry ice,' said Charles Williams, Chicago's streets and sanitation commissioner. 'It's more environmentally friendly, and it's very humane on the rodents as well.'" Humane or not, what is so especially "undignified" about rats? What makes them worse, than, for example, cats, deer or wild horses?
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How Cities Are Using Dry Ice To Kill Rats

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  • by Anonymous Coward
    Asphyxiation via C02 is an absolutely HORRIBLE way to die, regardless of the creature. There's a reason Carbogen (C02/Oxygen mix) is used to induce anxiety to test out anxiolytics. I mean I get that they need to solve the infestation problem but can't we choose a method that isn't also a completely inhumane method?
    • by Anonymous Coward on Friday September 16, 2016 @07:52PM (#52905063)

      who fuckin cares. They're rats.

      • We routinely kill pigs using CO2 as well. (I guess nitrogen is too expensive.)
    • by Anonymous Coward

      Well they tried C4 and the neighbors bitched about the noise. you just can't make anyone happy these days.

    • Asphyxiation via C02 is an absolutely HORRIBLE way to die, regardless of the creature. There's a reason Carbogen (C02/Oxygen mix) is used to induce anxiety to test out anxiolytics. I mean I get that they need to solve the infestation problem but can't we choose a method that isn't also a completely inhumane method?

      Not only that, but have you ever stuck your nose into a pure CO2 environment? It burns, because of the carbonic acid [ilpi.com] formed when the CO2 hits your mucus membranes. It would be a truly nasty way to die.

      But, yeah, they're rats.

      • by dbIII ( 701233 ) on Friday September 16, 2016 @08:11PM (#52905199)

        But, yeah, they're rats.

        The normal way is to make them eat a lot of warfarin until internal bleeding kills them.

        If you want to kill stuff than is not neatly lined up in the stockyards it's generally going to be messy and horrible.

        • If you want to kill stuff than is not neatly lined up in the stockyards it's generally going to be messy and horrible.

          And even if it is, it doesn't exactly measure up to your appendectomy.

    • by AaronW ( 33736 )

      After having dealt with rats in my attic, CO2 is a better alternative than the baits, which can poison other animals and make the rats bleed to death internally.

    • by Beeftopia ( 1846720 ) on Friday September 16, 2016 @10:19PM (#52905735)

      Asphyxiation via C02 is an absolutely HORRIBLE way to die, regardless of the creature. There's a reason Carbogen (C02/Oxygen mix) is used to induce anxiety to test out anxiolytics. I mean I get that they need to solve the infestation problem but can't we choose a method that isn't also a completely inhumane method?

      This is just not true. Low concentrations of CO2 can cause distress. High concentrations are fast and painless.

      There have been lake and volcanic outgassing events which release massive amounts of CO2 and it kills people and animals where they stand, in seconds.

      See the Lake Nyos incident to see how CO2 kills. [arizona.edu]

      And here's the final report on the incident from the USGS (PDF): "In this incident, asphyxia resulted from the displacement of normal atmosphere (approximately 21 percent oxygen) by a cloud of carbon dioxide gas. Under such circumstances, victims will literally "drop in their tracks" after taking a few breaths and experience no feeling of suffocation. The actual mechanism of death is believed to be a paralysis of the respiratory centers in the brain by very high concentrations of carbon dioxide. Lethal levels of carbon dioxide are in the range of 8 to 10 percent (Sittig, 1985)." - pp. 18-19 [usgs.gov]

      Also: "Additionally, many victims were found in their beds still covered by bed clothing. Victims found outside appeared to have collapsed suddenly without substantial movement. Animals were described as "dead in their tracks" in herds rather than dispersed." - page 17

      An accepted humane way to kill lab animals is with high concentrations of CO2. The key is "high concentrations."

      This concept, of dry ice generating carbon dioxide which flows down into holes at high concentrations, is actually brilliant and humane.

  • by fredrated ( 639554 ) on Friday September 16, 2016 @07:57PM (#52905103) Journal

    They carry disease, eat infrastructure, chew holes in your house, shit and pee on your stuff, chew holes in your stuff, eat and contaminate your food, and many more things I can't fit into the margin of this book.

    • by PsychoSlashDot ( 207849 ) on Friday September 16, 2016 @08:19PM (#52905249)

      They carry disease, eat infrastructure, chew holes in your house, shit and pee on your stuff, chew holes in your stuff, eat and contaminate your food, and many more things I can't fit into the margin of this book.

      Yes, children are unpleasant little monsters, aren't they?

      • You should see them when they grow up and start posting on the internet.

      • Children? I thought they were talking about humans. Nasty disease-ridden varmits - once they've infested an area you may as well leave, they're only going to keep multiplying and contaminating the area until it's unfit for anything but rats and cockroaches.

    • Useful clue for whoever wrote TFS: indignity is not the same as undignified. Yes, they both have "digni" in the middle. doesn't give them the same meaning.

      Bad enough when the commenters are semiliterate, now the editors are semiliterate too?

    • by Dutch Gun ( 899105 ) on Friday September 16, 2016 @09:28PM (#52905557)

      During World War 2 when the Dutch were near starvation late in the Nazi occupation, my grandmother - a young woman at the time, obviously - heard her baby sister suddenly start screaming from her crib in the next room. She rushed in to discover a rat chewing on the baby's chest.

      They're nasty, disease-carrying vermin, and anyone who feels sorry for them (or, idiotically, asks how they're worse than cats, deer, or wild horses) simply hasn't had a close encounter with them. I specifically keep cats around as nature's own anti-vermin patrol. My cats are well worth their value in purchased cat food and vet visits just for that function alone, and as a bonus, every once in a while they deign to permit me to pet them for a while.

      • Well, my kitteh brought a live mouse to my (mouse-free) house and set it free, without incapacitating first.

        On the other hand, once he kept, over the course of two days, bringing a lot of tiny mice and one big. Family reunion in the belly of a Master Race predator :)

  • by jrumney ( 197329 ) on Friday September 16, 2016 @07:58PM (#52905117)
    They still haven't shaken off the stigma of the bubonic plague. But somehow cats have gotten away with schizophrenia for all these years.
    • by sims 2 ( 994794 )

      Do cats cause schizophrenia? I thought it was the other way around.

      • Do cats cause schizophrenia? I thought it was the other way around.

        Schizophrenia causes cats?

        Who knew?

        • by sims 2 ( 994794 )

          Ahaha I missed the joke I get it now You were talking about cats being schizophrenics because they are all crazy and I was talking about crazy people that end up with 20+ cats.

          • by gtall ( 79522 )

            Cats are only crazy at night, they wait for us to go to sleep and then let loose.

      • by SuricouRaven ( 1897204 ) on Saturday September 17, 2016 @02:07AM (#52906339)

        Not directly, but they are the carrier for a very common parasite, T.gondii. It's endemic just about everywhere domestic cats can be found. It infects humans too, though it can't reproduce in them. In humans it concentrates in the brain, usually to symptoms so mild they go unnoticed - the victim just feels tired and slightly feverish for a short time - but the presence of the parasite has been linked to a number of mental health conditions.

        T.gondii is notable for influencing host behavior - it causes rats to become less fearful, increasing the chance of getting caught by a cat and consumed so the parasite can continue it's life cycle in a cat. The same mechanism of altering brain chemistry that causes rats to become less fearful is also active when it infects humans, but as it evolved to mess with rat brains the effect on humans is different.

        As a matter of public health, it would be wise to place restrictions on domestic cats - at the very least to deny them access to outdoors areas where they may have contact with wild animals. But cats are cute and everyone loves them, so such measures are politically non-viable.

  • Was the bubonic plague started by cats, deer or wild horses? Silly Op...

  • When I was a kid, I used to help my grandfather try to control moles around his cattle. Cattle, horses, etc. would step into the entrance to the mole's burrow and break a leg.
    • Re: (Score:2, Funny)

      by Anonymous Coward

      When I was a kid, I used to help my grandfather try to control moles around his cattle. Cattle, horses, etc. would step into the entrance to the mole's burrow and break a leg.

      Were you able to help all those moles with their tiny broken legs?

  • by TheCycoONE ( 913189 ) on Friday September 16, 2016 @08:13PM (#52905207)

    "Humane or not, what is so especially "undignified" about rats? What makes them worse, than, for example, cats, deer or wild horses?"

    The author of the summary has obviously never had a rat infestation. They can swim, dig several feet down, chew through concrete, plastic, wood, drywall, and otherwise go to amazing destructive measures to get to a heat or food source. Unlike mice, keeping your food in the cupboard or Tupperware containers is useless as they chew right through them, and destroy your home's foundation while they are at it. No, rats are not at all like wild horses, cats, or deer. Rats are a special kind of hell.

    If you need an ecological reason. The destructive urban rats are an invasive species, not native to North America. We brought them here - and I for one applaud every effort to get rid of them.

  • Worse (Score:5, Insightful)

    by Kohath ( 38547 ) on Friday September 16, 2016 @08:14PM (#52905219)

    Cats, deer, and wild horses generally won't climb walls and crawl into your house. And they don't share rats' long history of spreading disease and eating grain from storage containers. Deer are food. Horses can be tamed and used to do valuable work. Cats can be tamed and used to protect grain from rodents.

    • I'm with you on the deer and wild horses but let me introduce you to an Indonesian feral cat. My childhood nightmares were filled with these filthy creatures. They had mange, fleas and ticks. They were often deranged from rabies and would scream and fight at all hours. Oh, and they have a habit of pouncing on people. Get bitten or scratched and you had to get vaccinated for rabies. That required multiple injections in your belly. I have never understood my fellow American's tolerance for feline vermin.

      On

  • by tlambert ( 566799 ) on Friday September 16, 2016 @08:18PM (#52905237)

    Rats are very clean animals.

    Except, you know, for:

    lymphocytic choriomeningitis
    bubonic plague
    typhus
    hantavirus
    leptospirosis
    rat-bite fever (it's a real thing; look it up)
    salmonellosis
    Colorado tick fever
    cutaneous leishmaniasis ...but except for those, VERY CLEAN!

    • by Ungrounded Lightning ( 62228 ) on Saturday September 17, 2016 @12:04AM (#52906065) Journal

      Rats are very clean animals. Except, you know, for: ...

      They're also very friendly and cuddly. They tend to get into cribs with human infants and treat them like fellow rats: Cuddle up, clean their ears, etc.

      Unfortunately, rats react to a dead rat in the burrow by eating it. Humans, when they first fall asleep, tend to be in a deep sleep for something like 25ish minutes, from which it is very hard to rouse them - even by a rat bite. 25ish minutes is long enough for rats to decide a baby or child might be dead, test it by nibbling, then start chewing...

  • ... like how killing city rats may cause diseases to spread faster:

    http://nautil.us/issue/38/nois... [nautil.us]

    Now, it's possible that this technique manages to kill every rat in the colony, so they don't scatter ... but as rats that weren't in the burrow would realize that something is up when they come back, this could be a problem.

    I'd think they'd want to use carbon monoxide, not dioxide, at the very least ... assuming that rats have the same problems w/ humans in detecting it.

    • by wisnoskij ( 1206448 ) on Friday September 16, 2016 @08:51PM (#52905411) Homepage

      I really do not think there is a solution that involves not killing them. If you stopped killing rats for 4 months there would literally be something like a hundred times as many rats as there were before. They would explode out of the sewers and eat small children and babies in their cribs. Their ability to reproduce exponentially would mean that every edible morsel of food in the area, whether human, pet, or more generic foodstuff, would necessarily be converted into more rats within a few years time.

      • And they are mean sons of bitches. The people championing them here seem to think they're like lab rats, docile. Sewer rats are anything but. They will attack human infants and adults. I've been bitten by one in my sleep and seen a rat kill a cat.

        Mean sons of bitches.

      • Their ability to reproduce exponentially would mean that every edible morsel of food in the area, whether human, pet, or more generic foodstuff, would necessarily be converted into more rats within a few years time.

        Rats are nature's version of Grey Goo. [wikipedia.org]

  • by GerryGilmore ( 663905 ) on Friday September 16, 2016 @09:07PM (#52905475)
    ...I agree with nuking them. Living (voluntarily) in the country (North Georgia USA) I've come to very much appreciate the variety of life and their interactions, and I very much try to not screw with that to the degree possible. However...when the rats chew through my AC duct work and invade my living space, I kill the fuckers. I've drowned them, stomped them with boots and never felt an iota of the guilt of an errant daddy-longlegs caught in a bad spot.
  • Carbon Dioxide suffocation is pretty bad. It's basically the only form of suffocation your body is designed to violently react to. When killing rodents industrially for reptile feed, nitrogen suffocation is generally considered humane because they just fall asleep.
  • 'We are seeing 60% fewer burrows in areas where we are using the dry ice,' said Charles Williams, Chicago's streets and sanitation commissioner. 'It's more environmentally friendly, and it's very humane on the rodents as well.'"

    There is ongoing discussion over whether or not CO2 is humane for euthanizing rodents. It is not lack of oxygen that causes distress when holding your breath, but excess CO2. It is thought by some that lab and feeder rodents are put through unnecessary stress by using CO2 instead of an alternative gas/method.

  • nuke them from orbit or send in laser equipped alligators into the sewers?

  • Cats kill rats!
    they are not vermin, they control them.
  • Why is big government doing the job of the private sector?
    Who invested in vans, trucks, equipment and had to tender, bid for rat control work.
    Governments that set standards are using cheap science to alter the natural balance of capitalism.
    Think of the chemical sales, support jobs, local businesses that are all working to keep trucks stocked and chemicals flowing with the long term aim to stabilise rat populations.
    A large self supporting rat population can provide decades of control work, with very fe
    • by swb ( 14022 )

      The government does that job because the last time we used a private contractor, he stole all the children.

  • by sjbe ( 173966 ) on Saturday September 17, 2016 @09:58AM (#52907387)

    'It's more environmentally friendly, and it's very humane on the rodents as well.'"

    "Very humane"? Seriously? I don't have a problem with them taking measures to kill pests but suffocation isn't exactly what I would call humane. Necessary maybe but let's not pretend that they're doing something nice or pleasant to the rats.

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