The truth about insecticides used at Nui Dat



Insecticide deceit?:

By John Mordike*
Over the last two years I have undertaken a study on the use of
insecticides at the 1 ATF base at Nui Dat, the home of the Australian
and the New Zealand fighting force in Vietnam. The most important
finding of this study is that much of the truth about insecticide use by
1 ATF has never been revealed.
Taking a broad perspective, my study has revealed the roles played by
the Army, the Department of Veterans’ Affairs and the Department of
Primary Industry in the examination and reporting of the use of
insecticides by the Australian Army in Vietnam.
This article narrows the focus. It presents a synopsis of the findings of
my study in relation to the use of insecticides at Nui Dat.
The article is based on primary source documents from Army’s
Vietnam records. The records are held by the Research Centre,
Australian War Memorial, Canberra, and are available to the public for
research under the terms of the Archives Act (1983).
After the passage of forty years and a Royal Commission in 1983-5, it
is time the truth was revealed.
Developments at Nui Dat in 1970
In August 1970, the Officer Commanding Detachment 1 Field Hygiene
Company at Nui Dat realised that very serious errors were being made
with the use of insecticides. He brought his concerns to the attention
of Headquarters 1st Australian Task Force (HQ 1 ATF), Nui Dat. In turn,
HQ 1 ATF wrote to Headquarters Australian Force Vietnam (HQ AFV),
located in Saigon, with the advice that:
‘All insecticides/pesticides containing DIELDRIN are to be
withdrawn from issue, as in the Hygiene Officer’s opinion the
use of this chemical in any form is dangerous to humans …’.
The Hygiene Officer’s advice about Dieldrin was correct. He
subsequently advised that Dieldrin’s toxicity was officially rated as
‘Extremely Toxic’. Dieldrin was a very dangerous chemical and it
posed real dangers for human health and the environment. But there
were other very dangerous insecticides being used at Nui Dat, such as
Chlordane, Lindane and Diazinon.
How toxic were these insecticides?

On 22 May 2001, delegates from 120 nations, including Australia,
signed an international treaty banning twelve of the world’s most
dangerous chemicals in Stockholm. The dangerous chemicals were
described as ‘persistent organic pollutants [which] are among the most
dangerous of all manufactured products and toxic wastes which
cause fatal diseases and birth defects in humans and animals’.
Dieldrin was one of those chemicals. Chlordane was another.
Both of these insecticides were used regularly at the 1 ATF base at Nui
The Hygiene Officer’s advice should have brought a stop to the use of
Dieldrin, at least, in 1970. But it did not.
Army’s Supply Policy on Insecticides was Flawed
Although Dieldrin and Chlordane were banned internationally in 2001,
their extreme toxicity and danger to human health were known in the
1970s. Yet Army supply policy failed to reflect this.
When the Hygiene Officer’s advice to cease using Dieldrin was
considered at HQ AFV in August 1970, it was realised that Army’s
official supply policy placed no restrictions on the issue and use of
Dieldrin and any other insecticides with ‘extremely toxic’ and ‘very
toxic’ ratings. According to Army’s documented supply policy, any unit
could request these highly dangerous insecticides. Furthermore,
personnel dispersing them required no qualifications or training. It
was a very serious policy error.
My research has shown that, as a result of the policy and lack of
awareness, ‘extremely toxic’ and ‘very toxic’ insecticides were
dispersed at Nui Dat over a period of years in alarming volumes. An
indication of the quantities involved will be given later in this article.
Remarkably, the realisation in August1970 that the Army’s supply
policy was wrong produced no changes in the issue and use of
Dieldrin, Chlordane and other dangerous insecticides at Nui Dat. The
same insecticides were used again without restriction in 1971.
Two Classes of Insecticides
To assist in understanding what happened at Nui Dat, it is necessary
to understand how insecticides are classified and how they work.
Insecticides are divided into two classes which dictate the way in which
they are intended to be used:
• Knockdown Insecticides; &,
• Residual Insecticides

Everyone will be familiar with Knockdown Insecticides. They are the
insecticides that we use in our homes in pressure-pack spray cans.
The insecticide is released into the air in the form of an aerosol or
vapour. Knockdown insecticides are also dispersed by mosquito coils
and, for larger areas, by fogging and misting. The insect comes into
physical contact with the vapour or aerosol, generally when in flight.
The pyrethrum in the spray paralyses the insect while another mild
toxic element kills the insect. Because of their low toxicity, Knockdown
Insecticides are relatively safe to use in areas of human habitation.
Residual Insecticides function differently. This class of insecticides is
designed to be sprayed or applied directly to hard surfaces, sometimes
plants but generally buildings, where it forms a film which eventually
dries and crystallises. When the insect alights on, or crawls over, the
treated surface and remains in contact with the treated surface for a
period of time, it is poisoned and dies. To be effective, Residual
Insecticides require a high degree of toxicity and they also need to be
persistent, that is, they need to be long lasting. Only properly trained
personnel should use these insecticides in special circumstances under
close supervision.
Significantly, documents show that when the Hygiene Officer’s
representations were considered at HQ AFV in August 1970, it was
realised that the Army had no bulk Knockdown Insecticide in its
inventory. It never had. Therefore, all area spraying and fogging at Nui
Dat was executed with Residual Insecticides alone. This supply
problem was never rectified. The only Knockdown Insecticide available
was in the hand-held pressure-pack spray can.
The following table lists the range of Residual Insecticides used by the
Army in Vietnam. The toxicity rating of each – taken from the Hygiene
Officer’s documents at the time – are also shown. It will be noted that
Dieldrin and Chlordane were two of the most toxic insecticides.
Residual Insecticide Toxicity Rating
Dieldrin Extremely Toxic
Chlordane Extremely Toxic
Lindane Extremely Toxic
Diazinon Very Toxic
DDT Moderately Toxic
Malathion Slightly Toxic
Although Malathion was rated as ‘slightly toxic’ in the 1970s, in July
2006, the United States Environmental Protection Agency reported the
results of research that: “Malathion … is converted to its metabolite,
malaoxon … in insects and mammals’. The US EPA reported that tests
on rats showed that Malaoxon was ‘61x more toxic to adults [rats]
than malathion’. When Malathion was dispersed it could convert to
Malaoxon through oxidation in water treatment processes or through
reaction with ambient air. It was inevitable that Malathion dispersed
from aircraft over Nui Dat would settle on Rowe’s Lagoon, the open
water supply for Nui Dat. During the wet season, Residual Insecticides
would also have found their way into the water supply through runoff.
Further Developments at Nui Dat in 1970
In September 1970, a month after he first raised the issue of
insecticides, the Hygiene Officer wrote to HQ 1 ATF and HQ AFV with
the advice that:
‘Residual insecticides are dangerous poisons and therefore are
issued and used only by trained Army Health personnel.’
Apparently, the Hygiene Officer did not know that Army supply policy
permitted the ‘dangerous poisons’ to be issued freely to any unit and
to be dispersed by unqualified personnel. The officer then explained
briefly how Residual Insecticides worked and highlighted the problem
with the use of insecticides at Nui Dat:
‘It has been the incorrect practice in the past to use Residual
insecticides in a knock down capacity.’
Dispersing Residual Insecticides as though they were Knockdown
Insecticides was a largely ineffective method of eradicating insects,
but, significantly, as the Hygiene Officer pointed out to HQ 1 ATF and
HQ AFV, it was ‘somewhat dangerous to humans’.
Toxic insecticides could enter the human body through inhalation,
ingestion and absorption through the skin.
As a result of the Hygiene Officer’s advice, a senior medical officer was
alerted to the problem with insecticide use at Nui Dat. He commented
‘It is obvious that previous insecticide practice in 1 ATF is [sic]
And again in his end-of-tour report the same medical officer noted
‘Use of insecticides in 1 ATF has not been subject to adequate
Before leaving Vietnam on 23 December 1970, the senior medical
officer directed the Hygiene Officer to prepare an AFV policy document
on the use of insecticides.

In the draft policy document, the Hygiene Officer recommended that:
‘the chlorinated hydrocarbons, CHLORDANE, LINDANE, DDT and
DIELDRIN and any other of this group of insecticides be removed
from the scale of issue to Aust forces in Vietnam’.
There is no evidence that the AFV insecticide policy document was
ever promulgated. But, sadly, there is abundant evidence that the
same errors with insecticide dispersal were made at Nui Dat during the
next wet season in 1971; Residual Insecticides continued to be
dispersed in a knockdown capacity. Indeed, it is evident the method of
dispersal in 1971 was somewhat more dangerous for human health
than it had been in the past.
The Wet Season of 1971 at Nui Dat
On 15 May 1971, the Commander of 1 ATF issued Routine Order Part
1, Serial 28, Number 111. The subject of the Order was ‘Medical –
Prevention of Insect-Borne Diseases’.
In the introductory paragraph, the Order explained that insect-borne
diseases had caused high manpower loss in previous wet seasons and,
therefore, a co-ordinated campaign had been designed for 1971 to
combat the insect threat. Spraying insecticide from Australian aircraft
was to be the centrepiece of the campaign. In previous years, US
fixed-wing aircraft had sprayed insecticide over Nui Dat.
According to the Routine Order, the 1971 campaign was based on ‘the
latest medical advice’ and was to consist of the following measures:
‘(1) Residual spraying by fixed and rotary-wing aircraft initially
at fortnightly and later at weekly intervals.
(2) Residual spraying of bunkers and building interiors.
(3) Ground fogging of unit areas with residual and knock down
Remarkably, the campaign was based almost entirely on the use of
Residual Insecticide and, of most concern, the aerial dispersal of
Residual Insecticide.
Unfortunately, the Hygiene Officer who had warned in September – just
8 months previously – that Residual Insecticides were ‘dangerous
poisons’ and that using them as though they were Knockdown
Insecticides was ‘somewhat dangerous to humans’ was no longer
serving at Nui Dat. He had returned to Australia on 7 April.
Veterans who served at Nui Dat in 1971 recall that, each week, the
aerial spraying was executed by Iroquois helicopters from 9 Squadron
RAAF. Documents show that the helicopter spraying commenced on 25
May 1971.

My research has revealed that the documented medical advice given to
the Commander 1 ATF, like the Commander’s subsequent Routine
Order, failed to specify a particular insecticide to be used in the aerial
and ground spraying or fogging dispersal campaign. The medical
advice simply stated that the class of Residual Insecticides was to be
used in both aerial and ground dispersal. The lack of specific advice
opened the door for the use of dangerous insecticides.
Two Veterans Speak Up
In 1982, one veteran, who served at Nui Dat with 3rd Battalion RAR as
a member of the regimental hygiene squad, submitted a statutory
declaration to a Senate Enquiry on pesticide use in Vietnam. The
veteran said his duties ‘included dispersing Malathion and Dieldrin
with a swing fog device’. He went on to explain that he ‘did not dilute
any chemicals’ during his service at Nui Dat from February to October
1971. ‘Nor did any of the men I worked with to the best of my
knowledge.’ The veteran continued:
‘We sprayed to kill mosquitoes, cockroaches, scorpions and
snakes. The fog was dispersed under floorboards of tents, into
tents occupied by soldiers, between sandbags around tents,
around grease pits and rubbish cans, and kitchen waste areas.’
While undertaking this spraying, the veteran stated that he wore no
protective clothing, nor did his workmates. The veteran also stated
that after returning from Vietnam he had ‘suffered from a number of
medical problems including depression, nervousness and many bouts
of irrational behaviour’. His sons also had ‘medical problems’. The
veteran died in May 2011, aged 66.
Another veteran, who had served with 12 Field Regiment based at Nui
Dat in 1968-69 and again, in 1970, for a total of eight months with
the Detachment 1 Field Hygiene Company at Nui Dat, gave evidence to
the same Senate Enquiry observing that:
‘The high incidence of malaria and encephalitis caused
operators and supervisors to lift concentrations to very high
toxicity to achieve a kill. Many sprays were over three times the
usual concentration and mixed into cocktails of different
This veteran died in 1994 at the age of 46
What Quantities of Insecticides were used at Nui Dat?
On 15 October 1968, a Supply and Transport staff officer on HQ 1
ATF, wrote to the Deputy Assistant Director of Supply and Transport
on HQ AFV, informing him of the results of a survey of certain expense
supplies that were demanded by units at Nui Dat over a three-month

period. The quantities of insecticides being consumed at Nui Dat were
included in the survey and they are presented in the following table.
Insecticide Amount Used at Nui Dat in 3
Months – 1968
Toxicity Rating
Dieldrin 600 gallons Extremely Toxic
Chlordane 520 gallons Extremely Toxic
Lindane Powder 216 two-ounce cans Extremely Toxic
Diazinon Liquid 600 gallons Very Toxic
Diazinon Powder 300 pounds Very Toxic
DDT 222 gallons Moderately
Malathion 520 gallons Slightly Toxic
The supply officer who completed the survey recommended that these
usage rates be adopted to establish the working stock levels for
supply units at Nui Dat.
These are alarming quantities. In a three-month period in 1968, 1,120
gallons of ‘extremely toxic’ Dieldrin and Chlordane alone had been
dispersed at Nui Dat. Remember that both of these chemicals were
among the world’s twelve most dangerous chemicals that were
banned internationally in 2001.
It should be remembered that while the Australians were dispersing
these quantities of insecticides at Nui Dat from ground-based
equipment, US fixed-wing aircraft were also aerially spraying the base
with either Malathion, or, perhaps, DDT, each fortnight.
The quantities of insecticides being used in 1968 were not an
aberration. Other Australian supply documents from Vietnam show
that in mid-1970 there were 285 gallons of Dieldrin in stock with a
further 300 gallons on order, 35 gallons of Chlordane with a further
100 gallons due in, 100 gallons of Lindane Liquid with 300 gallons
due in, and so on with similar amounts for the other Residual
Why hasn’t this information come to light before?
Responding to the public controversy over the spraying of herbicides
in early 1982, Army Headquarters, Canberra, established a research
project to examine its 21,000 working files from the Vietnam war – the
very same records used to write this article. While the original aim of
the Army’s research project was to determine what herbicides had
been used, the scope of the project was expanded to include
insecticides and other chemicals that had been used by the Army in

Vietnam. Although this was essentially an Army project, Department of
Veterans’ Affairs also played a part in the research and writing.
The work of the research project was completed in May 1982. The
findings were incorporated in a large, complex document which was
known thereafter as the Army Report. But the original May version of
the Army Report was subject to some amendment action before
Minister of Defence Mr Ian Sinclair presented the report to Parliament
in December 1982. Mr Sinclair had already explained in October that
the ‘original version of the report [had] been revised to add
information where a more detailed description was felt necessary; [to]
make minor corrections such as spelling and typographical
corrections; and [to] make other editorial changes to improve the flow
of the report.’
The December version of the Army Report became an evidentiary base
for information on the exposure of Australian veterans to Agent
Orange, insecticides and other chemicals. Indeed, in relation to
insecticides, the Army Report was used by, and quoted extensively in,
the final report of the Royal Commission.
What becomes clear as a result of my recent study is that, on the
subject of insecticides, the Army Report is a most unsatisfactory
document. Indeed, I have discovered it to be riddled with obfuscation,
omissions and misleading comments. For the sake of brevity, only
three examples are considered here.
Failure to Report Aerial Spraying in 1971

When the Army Report
examined the contents of the medical advice given to the
Commander 1 ATF in May 1971 to implement an insect eradication
campaign, the report gave precedence to the ground spraying
program and simply failed to mention the aerial dispersal element.
Likewise, when the Army Report mentioned the Commander’s
subsequent Routine Order to implement the campaign, it reported
that the order detailed ‘the contents of a coordinated campaign
against insect-borne disease’. And that is all. The contents of the
campaign were not reported.
Therefore, in a remarkable omission, the Army Report failed to
mention the aerial spraying program of Residual Insecticides that
was undertaken on a weekly basis using 9 Squadron RAAF
helicopters. Aerial dispersal was the centrepiece of the whole
campaign. This was a critical omission because it had implications
for veterans’ health.
The Royal Commission accepted the Army Report as it stood, so it
too failed to report that RAAF helicopters had undertaken a weekly
spraying campaign of Residual Insecticide at Nui Dat, commencing
on 25 May 1971.

Thus Vietnam veterans were denied the possibility of Repatriation
medical treatment and benefits for illnesses that may have been
caused by exposure to these Residual Insecticides.
Obfuscation over Amount of Dieldrin DispersedSimilar
unsatisfactory reporting was evident when the Army Report detailed
the quantities of insecticides dispersed at Nui Dat.
The Army Report claimed that it could report accurately the
quantities of each insecticide used at Nui Dat on a monthly basis
from December 1967 to September 1971 because a detailed set of 1
ATF accounting records existed. So the Army Report listed all of the
insecticides in all their forms that were used at Nui Dat. For
example, there were 133,557 large pressure-pack aerosol cans,
2,832 pounds of Diazinon powder, 123,502 three-ounce bottles of
insect repellent and 2,360,350 packs containing 150 Dapsone
tablets. It was also reported that 2,792 gallons of Malathion and
2,940 gallons of Chlordane were dispersed by Australians at Nui
Dat. Yet in the midst of all this accounting accuracy, it was
remarkable that Dieldrin alone was the exception.
In the Army Report that was submitted to Parliament in December
1982, the amount of Dieldrin issued at Nui Dat over the four-year
period was simply listed as 430. But 430 what? The units of quantity
were not mentioned.
To claim that detailed Army accounting records did not designate
what quantity of Dieldrin was being issued, while all other
insecticides were accurately accounted for, is nonsense. While I have
never been able to locate the detailed accounting records cited in
the Army Report, I have found a number of documents in the Army
records held by the Australian War Memorial that show that Dieldrin
came from a US source in 5 gallon drums and that the Australian
unit of issue was the gallon.
Further highlighting the unsatisfactory reporting of the quantity of
Dieldrin issued, readers will also recall that the survey of usage
rates at Nui Dat reported that 600 gallons of Dieldrin had been
issued at Nui Dat in just a three-month period in 1968. The Army
Report, however, did not mention this documented fact.
Was this misreporting, incompetence or something more?
Again, the Army Report misled the Royal Commission. The final
report of the Royal Commission reproduced the usage rates listed in
the Army Report showing that 430 had been issued at Nui Dat, while
noting ‘quantity not specified’. Obviously, the commission took no
further action to find out the truth on this matter; it simply accepted
the Army Report without question.

A Significant Deletion in the Army Report   As already explained,
there were two versions of the Army Report. The first was completed
in May 1982, but, before being submitted to Parliament in
December, some amendments were made.
In the following extract from the original May version of the report, I
have emphasised in bold type certain words. These words were used
to describe the 1 ATF Hygiene Officer’s initial concerns about the
use of insecticides at Nui Dat:
The concern, that untrained personnel were apparently
using toxic insecticides without any knowledge of
concentrations, dilution factors, human toxicity factors and
general safety precautions, resulted in the intended
publication in Routine Orders of information on safe insecticide
Note : A draft routine order was discovered but it is not known
whether it was actually published.’
This statement was a succinct, realistic assessment of the situation.
But the statement was amended before submission to Parliament.
And the amendment was certainly beyond the scope of the revisions
explained to Parliament by Minister of Defence Mr Ian Sinclair in
The words I emphasised in bold type from the original May version
were deleted and the following statement substituted in the
December version:
‘The 1 ATF Hygiene officers [sic] concern that practices for the
use of toxic insecticides needed improvement resulted in the
intended publication in Routine Orders of information on safe
insecticide practice.’
Note : A draft routine order was discovered but it is not known
whether it was actually published.’
Who deleted the words ‘that untrained personnel were apparently
using toxic insecticides without any knowledge of concentrations,
dilution factors, human toxicity factors and general safety
On 25 November 1982, Mr Phill Thompson, National President of
the Vietnam Veterans’ Association of Australia put out a press
release claiming that Department of Veterans’ Affairs officers were
‘currently revising’ the original May version of the Army Report
before its submission to Parliament in December. Further evidence
from an Army officer working in Army Office at that time supports
this claim.

Whoever the culprits, it is clear they intentionally removed vital
information describing a longstanding dangerous misuse of toxic
insecticides. Why? The original words highlighted negligent practice
in the use of insecticides that could have led to searching questions
during the Royal Commission. It is also clear that the original words
would have helped veterans pursue claims for medical treatment
and compensation.
A Concluding Comment
The above examples raise key questions. Was information about the
use and misuse of toxic insecticides deliberately omitted or deleted
from the Army Report and to what end? Were any omissions and
deletions made to protect those guilty of possible negligence or to
deny exposed veterans grounds for their lawful benefits? And exactly
what part did the Department of Veterans’ Affairs play?
Given the rates and methods of dispersal of Residual Insecticides and
their toxicity and persistence in the environment, it is clear that the
Nui Dat base was an increasingly toxic and dangerous environment for
human habitation. Consequently, it is highly probable that the health
of Australian and New Zealand veterans was adversely affected. I
believe that a thorough examination of the morbidity of these veterans
is warranted.
As a final comment, it is certain that the Australian Army will never
again use herbicides – at least not on the scale and in the way that
they were used in Vietnam – but the Army will be using insecticides. It
is essential that the protocols developed for the use of these chemicals
consider the safety and well-being of soldiers as the first priority.
John Mordike
3 September 2013
*John Mordike is a Vietnam veteran and professional historian. He
graduated from the Royal Military College in 1966 and served in
Vietnam as the Officer Commanding 12 Field Regiment LAD. He has a
BA and LittB from the University of New England and a PhD from the
University of New South Wales. He is the author of ‘An Army for a
Nation : A history of Australian military developments 1880-1914’
and ‘“We should do this thing quietly” : Japan and the great deception
in Australian defence policy 1911-1914’.