06 December 2012
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Recent reports have suggested a link between the use of gypsum, from waste plasterboard and other gypsum-containing wastes, in animal bedding and a number of livestock deaths when mixed with slurries.
The agitation and mixing of manures and slurries in livestock sheds is already known to release hydrogen sulphide (H2S). The toxic gas affects the nervous system causing a range of symptoms including discomfort, disorientation, collapse, or sudden death.
As gypsum contains sulphur, mixing it with slurries will increase the total amount of hydrogen sulphide gas produced. Hydrogen sulphide will produce an odour but at concentrations above 140 parts per million, the human sense of smell becomes unable to detect the odour. At concentrations of 700 parts per million, hydrogen sulphide can be lethal. Farmers are reminded that the use of waste gypsum in slurry and dry bedding systems for livestock is illegal.
To understand the potential levels of hydrogen sulphide associated with the use of gypsum in animal bedding, SAC Consulting Environment and Design conducted an air quality assessment in September 2012. The assessment aimed to determine whether detectable levels of hydrogen sulphide gas could be found during the removal of farm yard manure from a site where gypsum had been used.
It was found that as soon as the farm yard manure was disturbed hydrogen sulphide gas was detected at levels up to 2705 parts per million, while carbon dioxide readings also increased.
Gavin Hill from SAC Consulting's Farm Rural Business Services said:
No matter what advantages are seen in using gypsum as animal bedding, it is simply not a risk worth taking. Recent tragedies have highlighted the issues that face us and we must take all steps to eliminate the risks."
Gary Walker, Principal Policy Officer (Waste), of the Scottish Environment Protection Agency (SEPA), said:
The results of this study illustrate the dangers associated with the use of waste gypsum in animal bedding. The use of plasterboard, gypsum and gypsum-containing wastes can lead to the production of the highly toxic gas hydrogen sulphide (H2S).
"When used in animal bedding, it is likely waste gypsum will produce considerable levels of hydrogen sulphide due to the damp, non-ventilated conditions. In such circumstances, hydrogen sulphide presents a significant risk to animal and human life, as well as the environment, and we would advise against anyone using it for this purpose."
Information from SAC Consulting and SEPA on the use of waste gypsum and slurry can be found at: www.sruc.ac.uk/gypsum
Notes to editors
SRUC was formed by the merger of Barony, Elmwood and Oatridge Colleges with SAC (Scottish Agricultural College).
For information and advice from SAC Consulting, please contact Gavin Hill on 0131 535 3434 or firstname.lastname@example.org.
SEPA Regulatory position
SEPA advises against the use of waste gypsum and gypsum from waste plasterboard in animal bedding on basis that it may present a serious risk to life.
As there are no exemptions in the waste legislation to allow the use of waste gypsum and waste plasterboard as animal bedding, any such uses may be reported to the Procurator Fiscal as an offence under section 33 of the Environmental Protection Act 1990.
SEPA will not agree to the use of plasterboard and waste gypsum as animal bedding until there is clear scientific evidence to demonstrate that it does not pose a risk to livestock, humans and the environment from hydrogen sulphide generation.
SEPA is aware that research into the use of gypsum in different bedding systems may be undertaken and we will review this SEPA Position Statement if and when the results of research become available.
The SAC study underlines the reasons for SEPA's clarification of the regulations.
SAC General enquiries Jane Smernicki, Head of Communications Tel: 0131 535 4331 or 07979 245 943 Email: email@example.com