Trial measures chemical exposure
Reporter: Sean Murphy
First Published: 23/11/2003

A quick swim in this portable dipping station and these sheep are instantly free from the scourge of ectoparasites such as lice.

But the Australian sheep industry's love affair with cheap, reliable organophosphates known as diazanon is under threat.

New South Wales Agriculture Livestock Officer Edward Joshua says diazanon, which has been around since 1957, is under review.

"The chemical is an anti-chlorino-esterase compound which reduces nerve action in the human body and its broad scale use in the industry can have an impact on human beings who use it and apply it and also people who handle the sheep or materials, wool, meat, after the fact so there's a whole heap of occupational health and safety issues for abattoirs and wool stores and all those people involved down the chain," Mr Joshua said.

"So it could easily be deregistered and lost to the industry.

"We need to be fully protected so none of the dip wash gets on us so we have to wear this waterproof stuff underneath everything we do.

"This is an experiment to measure what gets on people who use this equipment and do this sort of job and from there people will be able to make recommendations about what should or should not be used. The current recommendation is full length overall with gum boots, a hat and rubber gloves.

"In this case we're using a respirator, it hasn't got the normal cartridges in it, it's just got the filters so we're using this to measure what we inhale. It's not part of the recommended thin, it's just part of the measuring process.

With funding from Australian Wool Innovation, the University of Queensland's Centre for Pesticide Application Science, the National Occupational Health and Safety Commission and NSW Agriculture are undertaking a comprehensive study of diazanon exposure.

It's a $400,000 investment this year which could save the industry $400 million next year.

Mr Joshua says without this trial, there was a chance diazanon could be deregistered by Christmas.

The Australian Pesticides and Veterinary Medicines Authority's Joan Ashton says the authority has been reviewing its registration of diazanon since 1996 and has already banned some products.

"We've still got a range of products registered for continuing use on animals, particularly on sheep," Ms Ashton said.

"We basically have this chronic lack of information, a chronic lack of exposure data. This trial will give us the information to enable us to put a proper occupational health and safety assessment together and reach a good regulatory decision based on some hard data. Without this trial we would have had to make regulatory decisions based on assumptions and that would have been a concern for us and particularly users looking to retain these uses."

In the United States, diazanon products are being phased out of agriculture after a review by the Environmental Protection Agency. Chemical companies voluntarily withdrew their registration rather than pay for costly trials to prove their safety.

"In Australia it's somewhat different, our assessment has indicated we can be satisfied for some of the ongoing uses but where we've got these data gaps we've really said to the users we really need to obtain a bit more information in order to develop practices that are protective of your farm workers and also the environment," Ms Ashton said.

"All of our needs have to meet our legislative criteria and without these trials that would be a difficult thing for producers to do.

"Although a total ban on diazanon for on-farm usage is only a remote possibility it's a serious concern to the Livestock Contractors Association, which claims many of its members would be forced out of business and farmers would face massive cost increases.

In 1997, Landline reported an industry promotion:

"Sheep grazing has come of age, it is a highly technical business and among the techniques available to the grazier, none is more valuable than the buzacott rotating power spray dip.”

When this industry promotion was made, 60 per cent of Australia's national flock was lousy.

Improved techniques and application efficiency have halved that rate and although alternatives such as insect growth regulators are available, diazanon has stood the test of time.

"It's been one of our very reliable wet dips that've been available to us where over the years," Roger Lund, the NSW Agriculture Technical Officer, said.

"There have been quite a number of back lines and such like which have come and gone, that have suffered the problem of pesticide resistance. Diazanon doesn't have that problem, it's still a very reliable dip and its also very economic."

In 1997 Roger Lund headed a NSW Agriculture trial into more effective application techniques.

It was the so-called blue sheep trial because blue dye was added to the dip wash to also provide preliminary evidence on worker exposure.

"A lot of these wet chemicals actually rely on the sheep being absolutely saturated so that work was focused on wetting of the sheep but it was a great opportunity to follow through and look at how wet we actually got as operators," Mr Lund said.

The blue sheep trial helped improve application techniques but also led to new industry protocols for safer use of diazanon.

NSW AGRICULTURE VIDEO : "Power sheep conveyors improve sheep flow and reduce the effort required to dip large numbers of sheep they also allow operators to stand back from the dip and so reduce the risk of being splashed with insecticide. But it’s still advisable to use protective equipment."

"We're handling a wet product, we're handling pumps, we're handling a water based thing and we're handling wet sheep and in the past we've been a little inclined, it's done in hot weather, it's hot hard work, so we've been a little inclined to just have fairly minimal clothing on and just do it," Mr Lund said.

"The issue now is to have gloves and overalls, I know it's a little uncomfortable to do so but it doesn't in our opinion take much to overcome the problem of getting wet doing this work, so I think this work will indicate that we can safely use this product. It would be a shame if we lost it," Mr Lund said.

The diazanon worker exposure trials will continue in Stanthorpe, Queensland, later this month and its preliminary findings will be released next February.

Thanks to scientific protocols developed by the University of Sydney, those results are likely to aid Australia's regulator in any future registration applications.

CONTACTS

University of Queensland and Centre for Pesticide Application and Safety
07 5460 1293

NSW Agriculture(Trangie Research Station)

Australian Pesticide and Vetinary Medicines Authority
02 6272 5158

National Occupational Health and Safety Commision
Ph 02 6279 1000

http://www.abc.net.au/landline/stories/s986893.htm