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cremation urn ashes

Are human cremation ashes toxic?

Are cremation (cremains) ashes toxic?


Can they be harmful in any way?

Somewhat, if concentrated amounts are placed on grass it can cause a ‘burning’, a similar effect of putting on too much fertiliser. So they need spreading out and if you are putting them in the soil you need to dig them in to prevent concentrated matter in one place. Once spread out it appears that it will have either no impact or if in significant amounts it will take on some of the properties of a limestone soil.

Also, large amounts in sensitive ecosystems such as at the top of a mountain may alter the natural ecology – so don’t choo­se the summit!

Cremated remains are mostly dry calcium phosphates with some minor minerals, such as salts of sodium and potassium. Sulfur and most carbon are driven off as oxidized gases during the process, although a relatively small amount of carbon may remain as carbonate. – Wikipedia

Second Reference: The analysis of burned human remains By Christopher W. Schmidt, Steve A. Symes

17 thoughts on “Are human cremation ashes toxic?

  1. Reply
    Patrice Holmes - 21st July 2021

    If remains are handled several times without a mask or without gloves can be harmful to your body?

    1. Reply
      Richard Martin - 28th July 2021

      No it wont.

  2. Reply
    TJ Whetstone - 6th January 2021

    I live across the street from a funeral home that does cremations, and sometimes they don’t mix the oxygen at the proper level. That causes a dark, black smoke to belche out of the smokestack thta comes directly from the oven. I’ve seen it fill my neighborhood as well. The smell is the most disgusting you’ve ever smelled. So, I’m being exposed to partially cremated human remains. That is a far cry from ashes. That can’t be good for a person! What say you to this?

    1. Reply
      Richard Martin - 7th January 2021

      What say I? That is awful. I am guessing that you are in the States where localised crematoria are more common. If it was me I would report them to Environmental Health Team (I am sure there is a similar body where you are). You should not have to put up with that. I would suggest filming it too to go along as evidence with your compliant.

  3. Reply
    Erin - 12th December 2020

    If embalmed for a viewing is the cremated remains more toxic or does it burn off during cremation?

    1. Reply
      Richard Martin - 14th December 2020

      I have seen no evidence to say that ashes are more toxic due to embalming of a body. Modern embalming fluids are designed to be non toxic. Also bodies buried may be embalmed so they would go directly into the environment as such if there was any concern then this would not be allowed to happen. The temperatures used would indeed combust any embalming fluids. Therefore I would say that there should be no concern over increased toxicity of scattering the ashes.

  4. Reply
    jim Lawrence - 9th February 2020

    How many cremains to an acre would it take to become toxic to the water system? A company wants to move in next door and create a cemetery of cremains with apx. 1000 burial sites per acre in a wooded fir forest. Is this viable? It would happen over many years..

    1. Reply
      Richard Martin - 10th February 2020

      Dear Jim
      I am afraid I can’t give you a definitive answer, it would depend on an number factors including: depth of burial, soil type, uptake by plants inter alia. I would expect that the local authority would have asked for a environmental impact assessment as part of the planning – this should be a public document that you could refer to.
      Kind regards

  5. Reply
    Dr Moore - 23rd October 2019

    Ashes contain around 1 cup of salts. Salt is not good for soil biology and tree health. Ashes also have a ph of 12/14 the same as bleach and oven cleaner.

    Saying that scattering ashes isn’t as bad is like saying scattering cigarette butts isn’t as bad.

    Dilution is still pollution. The science around salt and photosynthesis is established.

    People that say ashes are not bad for soil biology could not possible have studied the impact of ashes on soil health.

    1. Reply
      Richard Martin - 28th October 2019

      Thank you for this, I appreciate you time and input. The question was are ashes toxic, I would stand by the argument that they are not.
      It is not the same as the cigarette butt argument. Cigarette butts are man made, they don’t break down and we create the demand.
      Humans live and then they die, the ashes are the bones. If a squirrel dies in a forest I doubt that there would be many bemoaning it’s bodies impact on the soil.
      Yes the salts are high and this has a negative impact on soil. I have not seen evidence that puts human ashes anywhere near a ph of 14.
      Humans are a natural thing, for thousands of years their bones have reintegrated back into the land. It’s like saying volcanoes are bad for air quality, true they are but they are the environment. We are the environment.
      The dilution agreement is difficult and I take the point – mercury, endocrine disruptors they all still bioaccumulate. But I don’t think concrenation the source is a valid argument the other way.
      Wide dispersal over wide areas seems a sensible and pragmatic approach. And I have only ever seen extreme cases where human ashes impacts the local ecosystem so greatly that it can’t support its original flora and fauna.

    2. Reply
      kristen burgess - 24th February 2020

      Would it be possible to contact Dr. Moore? I would be interested in his information. I am a geologist in the USA conducting studies on the effects of human ash on the forest floor.

      1. Reply
        Richard Martin - 25th February 2020

        I will see what I can find.

  6. Reply
    Mike M - 9th March 2018

    There’s a typo in your post: “so don’t chose the summit!” Should be “choose” not “chose”.

    1. Reply
      Richard Martin - 9th March 2018

      Oops thanks Mike

    2. Reply
      Farzaneh - 19th May 2023

      Does it smell bad if we burn it with fire?

      1. Reply
        Richard Martin - 24th May 2023

        You can’t burn ashes – they are what’s left after the burning process

  7. Reply
    Scattering Ashes on Radio 4 – Feed Me To The Wind | Scattering Ashes - 20th March 2012

    […] My only beef with the programme was the chap who went on at length say how toxic cremation ashes are, whilst the programme did balance this up, those I spoke to took away the point that they ‘ [had] never realised that cremation ashes were high toxic!’, in truth they a pretty much inert. See the post: are cremation ashes toxic? […]

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