A REPORT ON THE ANIMAL HEALTH IMPLICATIONS OF THE PLANNING
APPLICATION PK/08/0458/F FOR COMPOSTING OF GREEN WASTE
at
SOUTHCROFT FARM, OLD SODBURY, BRISTOL
by Roger Blowey, BSc.,BVSc.,FRCVS.,ARAgS
125 Bristol Road, Gloucester, GL2 4NB
1. CONCERNING ROGER W BLOWEY
I am a qualified veterinary surgeon, a registered member of the Royal College
of Veterinary Surgeons and an Honours graduate in Biochemistry. I have
spent over 30 years in general practice, where I specialise in herd health and
preventive medicine. I am author of a range of veterinary textbooks (for
example, A Veterinary Book for Dairy Farmers, Mastitis Control in Dairy
Herds, A Colour Atlas of Diseases and Disorders of Cattle, Bovine Medicine),
all of which are sold in both the UK and overseas. I have received numerous
Awards, including a Fellowship of the Royal College of Veterinary Surgeons,
and am one of a small number of Registered Cattle Specialists in the UK.
Much of my day to day work is associated with fertility, mastitis and lameness
control programmes in dairy herds, but I also provide a service as a general
veterinary practitioner to a wide range of farms. I work only with farm
animals.
I do not have expert knowledge on the composting of green waste, but I am
able to comment on the potential adverse effects of fungi and bio aerosols on
farm livestock. I have also had personal experience of animal health issues
associated with composting and ingestion of fungi and toxins
2. DOCUMENTS USED
I have not visited the proposed composting site at Southcroft Farm nor have I
discussed this case with the Applicant or with those objecting to the
application.
The information I have used was contained in letter from Alex Megaw of
Pannone LLP dated 25th April 2008, which included
-
a report from Ahlim Hashm dated November 2006, which was
commissioned by Julia Coulthard, plus appendices
-
the Environmental Agency Policy on Composting and the potential
health effects from bioaerosols dated 23rd October 2007.
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I received a subsequent email from Alex Magaw on 6th May 2008, containing
a site map showing livestock grazing areas.
3. THE PURPOSE OF THIS REPORT
In this Report I have
a. discussed my personal experiences to show that there is an
increased emission of bio aerosol during turning activities at an
exempt site
b. reviewed the potential adverse animal health conditions that are
known to result from exposure to bio aerosols, and especially
Aspergillus fumigatus
c. discussed the evidence showing that increased exposure to bio
aerosols increases the risk of animal disease
d. listed my own experiences of the adverse effects of fungi and
yeasts on animal health
Bio aerosols are clouds of mixed bacteria, yeasts, fungi and mycotoxins. There
may be no smell present and hence their presence may not be obvious to those
exposed to the noxious compounds.
4. LEVEL OF EMISSIONS FROM ANOTHER EXEMPT SITE
I am informed that Southcroft Farm currently has an exempt site where open
windrow green composting takes place. The composted green waste heats up and
is partially decomposed by an aerobic fermentation process. To facilitate the
fermentation, the windrows have to be aerated on a regular basis. This is
commonly achieved by lifting the material – a process known as ‘turning’ - with a
mechanical loader shovel. It is during the lifting, ie when the material is being
moved, that the majority of the bioaerosols are emitted
I have personally been involved in the taking of samples to check the level of
emission from a small exempt site at another location. A range of testing methods
is available to assess the atmospheric load of fungi. Many involve air samplers
that draw a fixed volume of air through a sampler and then measure the number of
colony forming units (cfu) per litre or per cubic metre of air. An alternative
method is to simply expose a plate to the atmosphere for a fixed period of time
and then culture the plate to quantify the organisms deposited. This latter method
has been used at exempt site that I have referred to above. The figures are too few
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in number to be statistically significant, but they do give an example of the
potential level of exposure.
Sabourald agar plates, ie plates that specifically grow fungi and yeasts, were
exposed for 15 minutes at each site, and then cultured for 5 days at 25C. The
results that were obtained during turning of the windrows are given in the
following
Sample site
DURING TURNING
Slightly to the side of windrows
during turning
Directly
downwind
of
windrows during turning
Also downwind of windrows
during turning
In cubicle shed during turning.
Cows were in and feeding at
the time
Downwind of windrows one
and a half hours after turning
windrows had finished
Fungi and moulds, Cfu per 15
mins exposure
50
68
89
42
35
Results clearly show
a. colony counts are higher during turning than after turning has been
completed
b. levels are higher outside during turning than in the cubicle house during
turning
c. colony counts in the cubicle house during turning are similar to counts
outside when turning has been completed.
On another occasion,. Sabourald agar plates were again exposed for 15 minutes,
then cultured for 5 days at 25C, but this time when no activity was taking place
near the windrows, ie no turning of compost nor tipping of waste. The results are
strikingly lower
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Sample site
NO TURNING
1. no action taking place at windrows.
Taken a distance from windrows near
proposed new site. No material near.
2. near to windrows no action at
windrows
3. close to windrows no action taking
place
4. close to windrows no action taking
place
5. in a field,2 miles away from
windrows
.
Fungi and moulds, cfu per 15 mins
exposure
10
25
41
39
7
These results show that
a. values are much lower on a day when no windrow turning is taking place.
Compare this table with the table above
b. Samples 2, 3, and 4, taken near to the compost site and near to the
windrows have higher colony counts than those some distance from the
site (= sample one)
c. Colony counts in a field two miles away are much lower and perhaps
represent the true back round level found on farms
The Report of Ahlim Hashm contains a map of the proposed composting site,
and it is clear from this that there is a significant area of pasture land
surrounding the windrow operations. This land is likely to be used either for
the grazing of cattle and sheep, and/or for the production of conserved forage
for later feeding to livestock, although I have not asked those using the land
what use is proposed for the future.
On 6th May 2008 I was informed that in the past this land has been used for
-
grazing of beef cattle, cows and young calves
grazing of horses
grazing of sheep
In my opinion the siting of a composting facility near to livestock or near to
areas used in the production of food for livestock, represents a significant
animal health risk. I have explored these potential animal health risks in the
following sections.
5. POTENTIAL ANIMAL HEALTH ISSUES FROM BIO AREOSOLS
Although much of the following refers specifically to Aspergillus fumigatus, it
should be remembered that a wide range of other organisms, yeasts and
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moulds, and toxic material such as bacterial endotoxins and mycotoxins are
emitted in bio aerosols from composting green waste.
5.1 Aspergillus fumigatus
Aspergillus fumigatus is a fungal infection that can cause a range of diseases in cattle,
pigs, sheep, poultry and man. Disease in cattle include
a.
abortion in late pregnant cows, caused by ingestion of infection. The
fungus passes to the placenta via the blood stream, leading to placental
degeneration and subsequent abortion. Documents are attached
confirming the importance of this syndrome (Appendix One - Colour
Atlas of Diseases and Disorders in Cattle p. 171 and Appendix Two ‘A
Veterinary Book for Dairy Farmers – VBDF - pages 4 and 274).
b.
pneumonia in young calves can occur, caused by inhalation of infection,
where the fungal spores can either be acting as an irritant (Appendix 3,
VBDF pages 72 to 74) or where the fungus becomes established and
grows in the lung tissue
c.
Mastitis, from fungi and/or yeast, resulting from topical exposure, can
occur at any stage of lactation, especially if cows are exposed to a heavy
environmental load (Appendix four). If this occurs in the last two weeks
of pregnancy, when the teat canal starts to open and the cow becomes
highly susceptible to infection the fungi may remain dormant in the udder
to cause mastitis at any time in the first three months after calving.
Although not the most common, Aspergillus and yeasts are significant
causes of mastitis in affected cows because they do not respond to
conventional treatment with antibiotics and many affected cows have to
be culled . In 100 mastitis samples cultured in our own lab prior to 1-1007 we grew yeast in pure culture in one sample and obtained a profuse
yeast growth from further 7 samples in association with one or two other
organisms. Hence from this small study the incidence of mycotic mastitis
in our own laboratory would be 8%
d.
If ingested in large quantities, Aspergillus can also cause digestive
disorders (Colour Atlas of Diseases and Disorders of Cattle, p.56,
Appendix five). I have very recently had personal experience of this on
the farm of a client in Gloucestershire. The top layer of the animal feed
was warm and contained a white mould typical in appearance to
Aspergillus. Almost 10% of the cows in this herd were affected by a
severe and painful digestive upset over the period of a few days. No
further cases were seen following removal of this material.
e.
Like all fungi, Aspergillus can produce toxins known as mycotoxins and
in sufficient concentrations these may also lead to health disorders in
cattle (Wilde 2005, Appendix six). One such disease is the pruritis-
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pyrexia-haemorrhagic syndrome (Colour Atlas of Diseases and Disorders
of Cattle, p.145, Appendix seven), and there are many other much less
well defined syndromes. There is currently so much concern over the
potential animal health and welfare issues associated with accidental
ingestion of mycotoxins, that many farmers routinely incorporate
supplements such in the feed such as ‘Mycosorb’ (Tm Allteck Ltd) to
counteract these effects.
5.2 Is Aspergillus an Opportunist Infection or a Pathogen?
It might be argued that fungal disease in cattle occurs only when the immunity
of the animal is compromised in some way, for example from poor feeding or
from intercurrent disease, and if this was the case then exposure to increased
levels of bio aerosols would be of limited importance. This is not my opinion. In
my opinion there is ample evidence that an increased exposure to Aspergillus and
other bio aerosols increases the risk of disease.
The major risk of Aspergillus and other mycotic diseases comes from
exposure to the pathogen. The higher the level of exposure, then the greater is the
risk of disease. Radostits et al confirm this, in that they state (page 1279 Appendix
eight) , when discussing abortion in cattle ‘The incidence of mycotic abortions is
much greater (up to 30% of all abortions in the herd) in the winter months in
housed cows than in any other group, probably because they are exposed to an
environment which is likely to be heavily contaminated with spores from mouldy
hay and silage. A correlation also occurs between the abortion rate and a high
rainfall in the hay making season prior to conception’.….’.
Caldow and Gray (appendix one, page 586, Appendix nine) also support this
concept, in that, when discussing the prevention of mycotic abortion, they are
concerned only with environmental factors, ie ‘…by reducing the degree of
contamination pregnant cows are exposed to, particularly in preserved forage’.
There is no mention of any involvement of immunosuppressant factors. In their
opinion, and I would support their view, reducing the level of environmental
challenge is the key factor in control.
The reverse of this is that increased exposure, such as would arise from an
adjacent composting facility, would increase the risk of disease, thus
compromising both health and welfare.
5.3. Natural levels of exposure of cattle and animals to Aspergillus fumigatus.
In paragraph 2.3 of her Report, Ahlim Hashm refers to Dr Burdens statement relating
to‘…..the many other farming activities which have the potential to increase the level
of bioaerosols.’
It is true that Aspergillus fumigatus was once a common organism in cattle feed and
the cattle environment. This has changed considerably in the past ten or more years
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however, and there has been a marked reduction in the degree of exposure of cattle to
the organism. This is due to three main reasons, namely

Changes in feed stuffs. Cattle were once fed hay and bedded on straw.
If either crop was baled when the weather was wet, then the risk of
exposure to fungal spores was high. It is now much more common to
feed the cattle on silage, and as this is made damp it does not normally
produce mould (exposure to air is the greatest risk for the growth of
mould in silage)

Changes in bedding. Cattle were once commonly bedded on straw, and
if baled damp this also lead to mould growth and exposure to
Aspergillus. More commonly dairy cows are now housed in cubicles
and lie on mats or mattresses, with bedding being sand, sawdust, wood
shavings, or waste paper products. Even if there is straw bedding
covering mats or mattresses, the quantities used are very much smaller,
and hence the risk of exposure to fungi is much less.

Changes in housing. It was once thought that cattle, including milking
cows, needed to be kept warm and free from drafts. It is now
recognised that one of the major reason why cattle are housed in the
winter is to protect the land, not to protect the cows. Dairy cows
especially, produce so much heat and moisture (around 50 litres per
day in the urine, faeces, breath and sweat) that buildings must be kept
very ‘open’ and well ventilated. This considerably reduces the risk of
exposure to Aspergillus species, and other noxious bio aerosols. The
importance of good ventilation and freedom from fungal spores and
other particulate material is also recognised in young stock housing,
where ventilation rates are much higher, bedding changes are more
frequent and great care is taken to avoid use of mouldy straw.
It would therefore be a serious retrograde step if composting once again exposed
cattle to high levels of bio aerosols.
5.4 Personal direct and indirect experiences with disease caused by Aspergillus and
other mycotic conditions
From my experience in farm animal veterinary practice over the years I am
well aware of the risks posed by Aspergillus and fungal toxins. These include
a. increased incidence of yeast mastitis associated with environmental
contamination from waste silage
b. digestive upsets in cattle associated with the feeding of mouldy
concentrate feed. (see paragraph 5.1.d above)
c. severe digestive upsets and death in cattle associated with the feeding of
grass silage that had had compost waste spread onto the pasture some 6
months prior to the silage having been harvested. Aspergillus was still
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present on the pasture 15 months after exposure, and a heavy growth of
Aspergillus was also present in the silage itself. In this instance the animal
health problems arose from the spreading of compost waste. In my
opinion the highly significant factor was that even though the waste had
been spread onto the field and a new crop grown, the Aspergillus was still
present 15 months later
d. increased levels of fungal abortion in cattle grazing near to an existing
composting facility. This was an exempt open windrow composting
facility, and the cattle were grazing within 250 metres of the composting
site.
The incidence of abortion in cattle has been reviewed by Caldow and Gray
(2004) (Appendix nine), and they concluded that a significant level of
abortions would be ‘.. 3% for abortions or losses after confirmation of
pregnancy after 6 weeks….’ Caldow and Gray also quote that 7% of abortions
are mycotic in origin (with 62% of these due to Aspergillus, one of the main
organisms arising from composting). At the farm referred to above, where
cattle were grazing within 250 metres of an exempt open windrow site, 60% of
the abortions were of fungal origin, ie grossly in excess of the 7% quoted by
Caldow and Gray The levels of fungi and moulds that these cattle were
exposed to were given in the tables in paragraph 4 earlier in this report.
5.5 Current levels of exposure of farmers to Aspergillus fumigatus.
The changes outlined in paragraph 4.3 above have also had an impact on human
exposure to fungal spores.
Farmer’s lung is a condition which was caused by inhalation of Aspergillus
Fumigatus fungal spores (1um – 3um in size) produced from mouldy hay, straw,
and crushed cereals fed to livestock. (See Lake, M, Appendix ten ).Mr Lake
refers to the current level of exposure of farm workers to fungi and bio aerosols
‘The Changes in farming practices, good health and safety programmes and the
use of mechanical handling methods to reduce dust levels, have been a
contributing factor in the reduction of incidences. Recorded numbers of
Aspergillosis have fallen sharply to a level where the condition is not at all
common’.
6. CONCLUSIONS
a. There is extensive evidence that there will be a significant emission of bio
aerosols, including Aspergillus, from the aerobic open windrow composting of
green waste.
b. This report has briefly described some of the more common animal health
disorders associated with the ingestion and/or inhalation of Aspergillus and
other mycotic organisms.
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c. I have had personal experience with the adverse animal health effects of
Aspergillus and other bio aerosol organisms.
d.
In my opinion the proximity of open composting windrows to cattle and
sheep grazing and to animal feed conservation areas, should be taken into
account when considering any planning application. This is in accordance with
the objectives of Article 4 of the Waste Framework Directive which states
that ‘Member States shall take the necessary measures to ensure that waste is
disposed of without endangering human health and without harming the
environment and, in particular: - without risk to water, air, soil and plants
and animals’.
Roger Blowey FRCVS
dated 6th May 2008
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Appendices
1. Blowey RW and Weaver, AD in ‘A Colour Atlas of Diseases and Disorders of
Cattle’, page 171
2. Blowey RW, in ‘A Veterinary Book for Dairy Farmers’ pages 4 and 274
3. Blowey RW, in ‘A Veterinary Book for Dairy Farmers’ pages 72 to 74
4. Blowey RW and Edmondson PE in ‘Mastitis Control in Dairy Herds’ page 41
5. Blowey RW and Weaver, AD in ‘A Colour Atlas of Diseases and Disorders of
Cattle’, page 56
6. Wilde D (2005) Proc British Cattle Vet Association 2005, pages 131 to 133
7. Blowey RW and Weaver, AD in ‘A Colour Atlas of Diseases and Disorders of
Cattle’, page 145
8. Radostits, OM, Gay CC, Blood DC and Hinchcliff KW (2000), in Textbook of
Veterinary Medicine, published by WB Saunders Company Ltd, pages 659,
876, and 1279
9. Caldow G and Gray D in ‘ Foetal Loss’, chapter 37 of Bovine Medicine,
second edition, edited by Andrews, Blowey, Boyd and Eddy, pages 577, 586,
published by Blackwell Scientific
10. Lake M (2002) in ‘Composting and Health’, page 46
11. Andrews AH (2004) in Bovine Medicine, second edition, edited by Andrews,
Blowey, Boyd and Eddy, published by Blackwell Scientific, pages 932 and
933
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