Review of atrazine—registration and review process

Section 2, November 1997

The National Registration Authority for Agricultural and Veterinary Chemicals (NRA) has reviewed the active ingredient atrazine, all products containing atrazine and associated labels.

The purpose of this document is to provide a report on the data evaluated and of the regulatory decisions reached, as a result of the review of atrazine.

1. REGULATORY INFORMATION

1.1 Powers of the NRA to review chemicals

1.1.1 Initiating a review

The NRA has statutory powers to reconsider the approval of active constituents, the registration of chemical products or the approval of labels for containers at any time. The basis for a reconsideration is whether the NRA is satisfied that the requirements prescribed by the regulations for continued approval are being met. Essentially, the prescribed requirements are that the requirements for the initial approval or registration continue to be met. These requirements are that the use of an active constituent or product, in accordance with the recommendations for its use:

• would not be an undue hazard to the safety of people exposed to it during its handling or people using anything containing its residues; and
• would not be likely to have an effect that is harmful to human beings; and
• would not be likely to have an unintended effect that is harmful to animals, plants or things or to the environment; and
• would not unduly prejudice trade or commerce between Australia and places outside Australia.

1.1.2 Obligations to submit data and other information on chemicals under review

On initiating a reconsideration, the NRA has to notify relevant approval holders or registrants of the matters it intends to reconsider and its reasons for doing so, and to invite them to make written submissions on those matters. These people are also requested to submit all existing information and data on the chemical under reconsideration, regardless of age or confidentiality. The NRA also notifies the community of the reconsideration and invites them to make submissions.

In addition to inviting public submissions, the NRA may consult with persons, organisations or government agencies with relevant knowledge or interests, for the purposes of obtaining information or advice relating to the reconsideration.

Once a reconsideration is initiated, the NRA may request additional information from approval holders and registrants. If such a request is denied, the NRA may suspend or cancel the relevant approval or registration.

1.1.3 Outcomes of reviews

There are three possible outcomes to an ECRP review:

1. The NRA is satisfied that the chemical under review continues to meet the prescribed requirements for the initial approval or registration and confirms the approval or registration.
2. The NRA is satisfied that the conditions to which the approval or registration is currently subject can be varied in such a way that the requirements for continued approval or registration will be complied with and varies the conditions of approval or registration.
3. The NRA is not satisfied that the conditions continue to be met and suspends or cancels the approval or registration.

The NRA must notify the approval holders and registrants of the outcomes of these reviews and must also notify the public.

Top

2. DATA PROTECTION

The NRA has recently introduced a Data Protection Program. The objectives of this program are:

• to grant protection to providers of certain information relating to agricultural and veterinary chemicals to provide an incentive for the development of products and data applicable to Australian or local conditions;
• to encourage the availability of overseas products and data; and
• to provide reciprocal protection for Australian products and data under overseas data protection systems.

In general, the NRA designates information as "protected registration information" for a "protection period" of two to seven years if it:

• is requested by the NRA for the purposes of reconsidering (reviewing) a product,
• is relevant to the scope of the review and
• relates to the interaction between the product and the environment of living organisms or naturally occurring populations in ecosystems including human beings.

If the NRA proposes to use the same information to determine whether to register, or continue registration, of another chemical product, the NRA must not use the information until the parties come to an agreement as to terms for compensation, unless the NRA is satisfied that it is in the public interest to use the information or the protection period has expired.

3. REASONS FOR THE ATRAZINE REVIEW

Atrazine was selected for review by the NRA Board after scoring highly against the agreed selection criteria for public health, occupational health and safety, agriculture and environment. In summary, the concerns over the chemical were:

• human and animal carcinogen claims;
• its moderate potential chronic risk;
• its potential to contaminate ground and surface water;
• absence of MRLs for major commodities;
• reported problems with use in agriculture; and
• high level of public concern.

Whilst the selection process ranked atrazine highly due to certain issues, the review was not confined only to those issues, but covered all aspects of the conditions of registration and approval of atrazine.

Top

4. CONSULTATION ACTIVITIES

There was a high level of public interest in the review of atrazine. One hundred and seventy six submissions were received in response to the NRA's call for information on atrazine. These came from individuals, environmental and community groups, and from the agricultural and plantation forestry industries. The submissions varied widely in their length and level of detail and submissions presented in this section have been edited, and the issues raised collated, for ease of access. However, where possible, the words of the original submission have been maintained. Therefore, the information provided and views expressed in this section are those of the authors of the submissions, and have not been validated by the NRA.

At the beginning of the review process, the NRA agreed not to publish the identity of authors of submissions. However, each submission is classified according to the following categories:

Individual, Community Group, User, User Group, Government Department, and Industry.

Each submission also has a unique identifier number [in brackets]. Attachment 1 matches submission numbers with the above categories.

4.1 Environment and public health

4.1.1 Water contamination

Atrazine is routinely used to suppress weed competition during plantation establishment by the Plantation forestry Industry. This use produced 22 submissions regarding water contamination resulting from such activity. Submissions raised the following concerns:

• Shallow ground water, due to raised water table and farming practices, is vulnerable to contamination by infiltrating chemicals and microbes relevant to public health [37].
• Atrazine is persistent in the environment, mobile and should be not be used where it is likely to leave the site of application [25, 153, 154].
• Unacceptable that atrazine is used in areas where it can contaminate drinking water, no matter how slight the risk to humans and aquatic life [3].
• Contamination of water and aquatic ecosystems is occurring despite use according to label instructions and concerns the people living in areas where it has been used [97, 125, 134 a to f, 138, 152].
• According to Australian Drinking Water Guidelines, atrazine should not be detected in drinking water and if so, remedial action is required to stop contamination [134d, 146].
• Other guidelines cited levels of atrazine in drinking water: 2 ppb (WHO), 0.1 ppb (EU), 3 ppb (USA), 20 ppb proposed (NH&MRC, Australia). At levels above 10 ppb aquatic life is observably affected [146].   
• To successfully remove atrazine from water, granular activated carbon filtration or advanced oxidation processes are required. This is uncommon in many surface treatment facilities in NSW, except where removal of tastes, odours and toxins due to blue-green algae is required [170].

4.1.1.1 Australia

North West (NW) Tasmania

Several submissions were received providing details of alleged contamination of surface water in a small area of NW Tasmania. These report that, it was proposed to spray atrazine and Roundup (glyphosate) in a catchment area in NW Tasmania supplying water to a community of about 50 people [25, 134a to f]. Protest from local residents resulted in wider buffers on creeks, ground based spraying and some chemical-free areas. In May, 1993 atrazine and Roundup were sprayed in the area amid continued protest. When the rains came the following July, the domestic water supply was found (by the Tasmanian Department of Environment and Land in August, 1995) to be contaminated [1, 25, 108, 134d, 146, 154] at levels many times the WHO standard [146]. The plantation forestry operator involved voluntarily withdrew atrazine [108, 134d]. Other comments on this incident were:

• Atrazine was still present 12 to 18 months after spraying at levels described as: double the acceptable European levels (no levels given) [108], unacceptable levels [146], above EEC guidelines (0.1 ppb) [25] and up to a few ppb [133].
• Sampling is only carried out in areas where there has been public concern, so State-wide contamination is not known [25].
• Off-label use [108, 134d] is allowed at higher [125] or eight times [108] the recommended application rate.
• The NRA, following repeated pollution events, withdrew atrazine from use by municipal authorities but allowed its continued use for plantation forestry under conditions less stringent than those in which some of the instances of drinking water contamination have occurred [152].
• Aerial spraying is not safe for either the operator or the community due to vapour drift. It has been shown to occur around affected local communities [151].

Other areas

Submissions relating to atrazine contamination of drinking water in other areas of Australia were also received. Details are as follows:

• It was claimed that in June 1994, atrazine was sprayed in a water catchment area in North East Tasmania which resulted in water becoming contaminated [25, 146].
• A submission referred to a chemical manufacturer's own study which found traces of atrazine in six samples of water from agricultural dams in Queensland and also in some areas in South Australia and Western Australia. The manufacturer considered this as posing no risk to public health. The author of this submission also regarded the directions for use "along creek banks" and the warning "do not contaminate waterways or drains" as contradictory [122].
• One submission presented data on atrazine contamination in Shepparton East and the Padthaway-Coonawarra regions of South Australia. Half the samples collected in Shepparton East were contaminated, with levels generally well below NH&MRC draft guidelines [20 ppb]. Three quarters of samples from the Padthaway-Coonawarra region were contaminated and of these two thirds contained breakdown products of atrazine (compared to a third of samples taken in Shepparton). Included in this submission were press clippings regarding atrazine in ground water and in a kindergarten tank [37].
• Atrazine is reported to be widely used through out the south east of South Australia. One submission stated that atrazine is found in the flesh of fruit and vegetables, and cannot be washed off. Also, the relatively shallow depth to ground water in many areas and the "high permeability of most unsaturated strata above the water table increase the potential for ground water contamination in South Australia". Atrazine has been detected in confined aquifers at Keith and Padthaway (quoted information from the E & SW Dept of Mines, 1988 and 1989); ground water in Mt Gambier at up to 8.6 mg/L (mean of 2.0 mg/L, 12 wells sampled). Ground water under Mt Gambier recharges the Blue Lake, source of the city water supply [157].
• Atrazine is reported to be used extensively in the Gunnedah region of NSW. This submission quoted a report from the 1994-1995 Department of Land and Water Conservation Water Audit, which stated that the region continues to have widespread atrazine contamination in both river and ground water which pertains to the Gunnedah and district drinking water. Concerns about long term, low dosage, involuntary exposure to chemicals (including atrazine) in water and about further contamination with the rain after the 5 year drought were also expressed [29, plus 40 letters of support].
• One submission provided information on the 1993/1994 monitoring program in the Murrumbidgee irrigation area drainage system in NSW that reported atrazine levels up to 4.4 mg/L during January 1994. Atrazine is used with metolachlor on maize crops during the hot dry periods. These crops were sprayed during December/January and irrigation caused contamination of the drainage system. The submission also reported that the EPA (not stated if State or commonwealth) have a notification level of 2 mg/L and an action level of 10 mg/L [168].
• Information was provided on an environmental investigation into the impact of agriculture on water quality within the Macquarie, Namoi, Gwydir, Macintyre and Barwon Rivers in NSW. Atrazine was widely detected in the area; for example, sampling after two storm events, showed levels peaked at 15.1 mg/L in the upper Namoi basin and  Thalaba Creek in the Gwydir basin, has reached a maximum concentration of 220 mg/L (over ten times greater than the 1994 Draft Australian Water Quality Guidelines). These elevated concentrations are cause for concern and water user groups have indicated a desire to further investigate and rectify these occurrences. Preliminary assessment of the macroinvertebrate communities living in and on the creek sediments has shown a decrease in the number of taxa [170].

4.1.1.2 Overseas

Comments mainly referred to the situation in the USA or in Europe. The following comments were received in relation to the USA:

• Atrazine contamination is found in 18 States [25] or 50% of ground water [1]. Australia doesn't need to get to this point before the use of atrazine is curtailed [97].
• An American study of ground water showed all clear, except for Nebraska [21].
• One respondent noted that banning of atrazine was considered by US EPA in 1991 [6].
• High atrazine levels in US and European water is due to frequent and high applications of atrazine on corn [171].

Comments on other countries include:

• Atrazine was banned in Germany in 1991. Holland and Germany proposed a ban to cover the whole of the EEC. Temporarily banned in Italy in 1990 and extended in 1991 because of ground water contamination and high levels in drinking water [25].
• Atrazine is banned in at least one overseas country [6].

Top

4.1.2 Primary produce concerns

Seven submissions were received from Tasmania and one from Gunnedah, NSW concerning possible contamination of primary produce as a result of atrazine contamination of waterways and ground waters which are used to water stock or crops. One submission [153] refers to Department of Primary Industry studies indicating that triazines show up in milk at almost the same levels as in the water cows consume. It also concentrates in the fat of meat.

• The Gunnedah submission was concerned about the local beef industry because of the increased chemical usage in the region as the area has moved to cotton growing [29].
• In Tasmania, concerns related to the plantation forestry use of atrazine, as follows:
• Levels up to 14 ppb found in stock water also used by humans [153].
• Use, and sometimes over use, by plantation forestry industry seen as detrimental to agricultural produce of the region [3, 134 a to f, 138].
• Many of the water courses affected are in a dairying district. Concern that consumption of contaminated water could result in the appearance of atrazine or its metabolites in cows' milk [133].
• Organic growers and those producers exporting to countries with stringent controls on chemical contamination of food products could be adversely affected [134 a to f, 138, 153].
• Long term low levels (1-20 mg/L) could suppress stream primary productivity [25].
• Use of contaminated water not in keeping with best practices for agricultural products [138].

4.1.3 Effects on ecosystems

Two submissions were concerned about the effects of atrazine-contaminated water on local ecosystems.

• Atrazine is applied to sugarcane fields which flood two or three times a year and drain into a nature reserve. There was concern that this may affect plant life in drains, adjacent wetlands and the nature reserve [155].
• [134 a to f] referred to research findings as follows:

* US Department of the Interior Fish and Wildlife Service work shows that aquatic animal life is indirectly affected at atrazine concentrations above 20 ppb, partly through reduction of the food supply of herbivores and partly through loss of macrophyte habitat. There could be an indirect effect of atrazine on seed and insect-eating birds which should be investigated.

4.1.4 Public health

The major public health concerns were the claims regarding hormone and reproductive disruptive effects of atrazine and its links to cancer. Comments were also received on the potential danger from atrazine metabolites and their synergistic behaviour with other chemicals. One submission [97] quoting from an article in the Toxic Network News stated "the precautionary principle demands that a decrease of the chemical load should be foremost in the minds of regulators concerned with care for the environment and public health." Other comments on public health issues were:

• Atrazine is wide spread in the environment and purported to have reproductive and hormone disrupting effects in laboratory animals, wild life and/or humans [25, 156].
• Atrazine is classified as a 2B carcinogen by WHO [25, 125] and considered by the USEPA as a possible human carcinogen [97, 152]. It is linked to ovarian tumours, non-Hodgkins lymphoma [25, 152] and with breast and testicle tumours [138, 152].
• Atrazine breaks down to further hazardous substances [25, 154]. US research has demonstrated corn plants convert atrazine to a mutagenic substance [122]. In combination with nitrogen, it produces dangerous synergistic effects [152].
• One submission [97] cites numerous studies indicating that atrazine may pose a health risk to humans after long term exposure.

4.2 Agriculture

125 submissions were received from the farming sector. In general, they supported the continued use of atrazine and expressed great concern if it were removed from use. Farmers also stated how they had used atrazine for many years. An additional five submissions from Tasmanian farmers [134 c, d, e, f, 146] did not support the continued use of atrazine due to water contamination problems resulting from plantation forestry operations (as discussed above).

4.2.1 Farm management

4.2.1.1 Minimum tillage

Farmers report that atrazine occupies an important role in weed control with the movement from mechanical cultivation to minimum tillage. Without atrazine they would return to environmentally damaging excessive cultivation. Submissions outlined the resulting benefits of minimum tillage:

• Improved soil fertility [21, 106], soil structure and a decrease in soil erosion [8, 19, 20, 21, 34, 95, 106, 118, 123].
• Stubble retention practises achieves a 95% lowering in soil loss to less than 3.0 t/ha [99] and a decrease in water use [21, 79, 106].
• Organic farming uses many passes with mechanical cultivators to control weeds which leads to soil erosion [107].
• Use in the wet season fallow period reduces the amount of mechanical weed control which, due to the high rainfall, would encourage erosion [129].
• Self mulching clay soils in Central Queensland are mainly used for grain farming. In a tropical climate situation they are extremely prone to soil erosion if farmed conventionally. Dependant on chemicals to give the best overall land care option [79].
• Decreased machine use resulting in fuel savings [21, 106].
• Improved profitability [106].
• Greater utilisation of sloping land [21].
• Used in conjunction with crop rotation strategies [2, 75, 106, 110] and strategic grazing [136].

4.2.1.2 Minimal chemical use programs

The proper use of chemicals, such as atrazine, in agriculture was considered by 3 submissions [21, 27, 28] to be compatible with ensuring high standards for the environment, occupational health and safety, public health and product quality. Two farmer organisations said this was achieved through a planned management approach to ensure safe and sustainable use of chemicals that emphasises minimal use [27, 28]. Programs and policies to achieve this aim were as follows:

• A code of practice for aerial spraying [27, 28].
• Education through accredited courses (for example, the National Farm Chemicals Users Training Program) to develop responsible use practices [27, 28] and minimise risks to farmer and the environment. These organisations encourage such activities and monitor them [9].
• Landcare programs to minimise use of chemicals and promote environmental awareness in newsletters [27, 28]. Ten years ago chemicals were used in higher amounts resulting in residue problems. Farmers had to wait 18 months before they could grow atrazine-sensitive crops such as canola, soy, faba and tomatoes. The introduction of more specific herbicides to control grasses now means less atrazine is used (submission also outlined these current practices) [31].
• Promotion of Integrated Pest Management programs which use biological and mechanical, as well as chemical control methods [27, 28]
• Liaison with government departments [27, 28].

The result is reported to be a decrease in the use of chemicals over the last 10 years, helped by changes in application technology, more sophisticated supplier support and a greater general awareness about health and safety issues [21].

The possible deregistration of an important chemical such as atrazine was of great concern particularly where responsible use is occurring [8, 21, 27, 28, 31, 32].

4.2.1.3 Uses and advantages of atrazine

Atrazine is viewed as an important herbicide for the control of a wide variety of broad leaf weeds and grasses in crops. It has a role in combating weeds resistant to other herbicides, a major threat to the agricultural industry, and its persistence in the soil gives greater control over longer periods.

Atrazine is used for pre and post emergence weed control [10, 30, 99, 118, 132] of the following weeds: Yellow vine and black oats [110]: Datura [112]; climbing buck wheat, a hard to kill winter weed [162]; barnyard grass [112, 127]; urochloa grass [112]; mint weed [112, 127] and Parthenium weed [32, 79, 109, 130, 169]. Parthenium weed, in particular, is difficult to control and germinates year round so comes up in corn and sorghum during the growing period. This weed is also a health problem as it can cause serious allergic reactions such as dermatitis and hay fever [169]. Atrazine is regarded as the only herbicide available to combat Parthenium weed. Reported rates of use are 1.0 L of atrazine used post planting on crops [79] and road side spraying in Queensland at 4 kg ai/ha to provide year-long residual control [169].

Sometimes atrazine is the only chemical available for use, due to weed resistance [28]. Atrazine is used on chlorsulfuron-resistant Phalaris (grass weed) in the fallow or in crops such as sorghum [95] and glyphosate-resistant weed species in fruit crops [30].

At higher rates atrazine is reported to be used, pre-emergent, as a soil residual herbicide in non-crop situations, killing weeds as they germinate [24, 163]. Such uses are:

•  In head and tail drains [131], dam catchments [41] and irrigation hygiene [158].
• Around sheds and pumps to decrease vermin [42].

6 submissions commented on atrazine residues:

• Other crops, susceptible to atrazine, are grown in rotation with sorghum so the chemical is never applied more than twice over 5 years. This avoids residue build up and weed resistance [54].
• Results from State chemical testing laboratories show minimal residues from year to year [2]. Residue testing shows atrazine is not found in the soil [57].
• Paddocks are double cropped with an atrazine susceptible winter cereal. This shows atrazine has broken down in the area's warm wet conditions within four months [141].
• Residues persist for shorter periods of time in areas of higher temperatures and long periods of sunlight. One application barely lasts for one growth cycle [49].
• Residual characteristics give winter, spring and summer weed control [162].
• One submission stated that the previous owner of the property used both atrazine and 2,4-D at higher than recommended rates for Parthenium weed control. The current owner is now having problems with weeds and difficulty with grass establishments and is concerned that chemical residues are responsible [166].

Other comments on the uses and advantages of atrazine were:

• Not used extensively but when used has sometimes made the difference between an economic crop and one that makes a loss [124, 128].
• Small use in fruit [76].
• No problems using atrazine in farming operation which include tomatoes, sunflowers and a vineyard [87].

4.2.1.4 Cost effectiveness

22 submissions commented that atrazine was a cheap, broad spectrum and most cost effective herbicide [59, 60, 61, 62, 65, 68, 69, 71, 72, 74, 77, 79, 81, 83, 84, 86, 89, 90, 91, 92, 93, 162]. There were either no alternatives [43, 44, 45] or there were, but these alternatives did not offer the same low cost or spectrum of weed control [4, 10, 17, 42, 43, 45, 46, 53, 95, 110, 117, 118, 128, 129, 132]. The following comments relate to possible problems if atrazine becomes unavailable:

• Alternatives cost 2 to 3 times [35, 53, 57] or 3 to 5 times [23, 24] more. This would disadvantage operations [131], affect livelihood [11, 12, 13] or cause hardship given problems already with drought and mice [45].
• Substitute not easily found nor economically viable given the horrendous cost and time associated with new registrations [14, 28].
• Other residual alternatives exist but not well tolerated by crops [23].
• Replacement must be economically and environmentally good [33], need suitable alternative [46].
• US has an alternative (not specified) [33].

Top

4.2.2 Water contamination

Information relating to  atrazine use in agricultural areas and water contamination was provided in 11 submissions. Highlighted were the differences between soil conditions in Australia and overseas, farming practices designed to minimise run-off and the lack of evidence of contamination of water by atrazine. Specific comments are as follows:

• One of the major conduits for atrazine to arrive in waterways has been soil erosion [95].
• The incidence of atrazine in waterways in New South Wales is largely associated with the run-off of tail water from irrigation areas. With current attitudes to control of tail water [70, 95] and the need to improve efficiency of water use this is unlikely to be a problem in the future [95].
• Details of a four year study in the 100 000 acre Beaver Creek catchment area (Tennessee, US), was conducted by the Illinois-based Conservation Technology Information Centre in conjunction with the USDA [95] were provided. The major findings were:

*Sediment resulting from soil erosion was identified as the major water quality problem. No till farming systems are the main way in which erosion can be controlled and the nutrient and pesticide content of the run-off reduced.

* Little or no movement of other chemicals was found (besides aldicarb) unless there was heavy rainfall within a day or two of application.

• Two major advantages to use of atrazine in Australia over use in other countries [9]:

* Many of the soils have a high clay content which renders leaching of atrazine insignificant.

* Atrazine, whilst relatively immobile, is not subject to excessive irrigation or rainfall in Australian cropping environments which would make any effective leaching of the product unlikely.

• The author of one submission had been involved in the initial research, development and extension programs using atrazine. He reported that significant differences in the performance (herbicidal activity and selectivity) of atrazine under Australian conditions (soil and soil moisture, climate, irrigation practices) had been found, compared with overseas [116].
• Heavy soils in the area have been tested for leachability to ground water and have been found to be very safe [106].
• In Queensland, most of the sorghum is grown on high clay content soils where the movement of atrazine is minimal and ground water contamination unlikely [99].
• Problems with atrazine addressed in the US where labels state the chemical is not to be used on sandy soils or soils where it is likely to be leached into the ground water. No trace of atrazine found in local bore water (results presented) [107].
• Strip farming of the land (where a barrier is always in place to reduce run off of both water and soil) and no till farming methods have effectively eliminated the run off of atrazine into non-farming land and into waterways [112].
• In the spring of 1994, the Richmond river at Casino was monitored downstream for any pollution problems. No pollutants were found in this high rainfall area [141].
• Atrazine residues have been found in Esperance (WA) water in the past. The author considers that this resulted from defoliating around bores by the Water Authority. These bores were many kilometres from agricultural activities [149].
• Work carried out by the Queensland Wheat Research Institute in Toowoomba has not found any leaching problems with atrazine [158].

4.2.3 Public health and the environment

Several submissions from users considered the use of atrazine to be generally 2safe for people and the environment:

• Considered safe for the spray operators to handle [132].
• Comparatively low rates used not an environmental problem [2, 18].
• Low rates used (once a year) in large broad acre farming in Western Australia would be difficult to detect in ground water and streams and not considered an environmental or health risk [16].
• Significant changes in application technology, more sophisticated supplier support and general user awareness about health and safety issues has reduced risks to health [21].
• No personal knowledge of long term environmental damage [7, 8, 12, 13, 43] or adverse human health effects [33, 34, 35, 58].
• No detrimental side effects if used with astute farming practices [12, 14, 31, 32].
• Low mammalian risk, regarded as safe to fish [31, 43].
• User friendly [43, 49, 53].
• Low drift [57].
• Referring to water contamination in Tasmania, two submissions said atrazine levels were within WHO guidelines for drinking water [23, 24] others say no cases of contaminated water [49].

4.2.4 Specific crop issues

4.2.4.1 Grain

Relevance to grain farmers

Grain farmers consider atrazine to be very important to the production of high quality grain, including sorghum and maize. General comments are included above under Farm Management. Specific comments relating to the importance of atrazine in controlling the medium to high weed burden on crop growth are provided below. Atrazine is convenient and applied early in the season when weather conditions are conducive to easy and effective management [10, 30]. Crops grown in a high rainfall area need weed control at planting because it can be too wet to travel in the paddocks later [141].

Minimum tillage

Several submissions also provided details of farming practices utilising atrazine and minimum tillage methods, as follows:

• The winter crop (usually wheat) is harvested in November. The stubble is left and sprayed with atrazine at rates of 1.0 - 2.0 kg ai/ha. A knock-down herbicide is added to the atrazine mix if necessary. No tillage occurs for 11 months and grain sorghum is planted in October into the undisturbed stubble [136]. Alternatively, rates of 1.2 kg ai/ha (mixed with Metolachlor) [44] or 2.0 - 3.0 L/ha atrazine mixed with 0.35 - 0.5 L/ha of Starane 200, Tordon 75-D or 2,4-D [5, 99, 162] are used. Low rates of 1.0 L/ha are used, on a regular basis, to control radish and erodium weeds [149].
• Rotations of sorghum, sorghum, wheat, sunflower and chickpeas have produced no detrimental effects [161]. No evidence of crop damage or residues damaging a following crop [34, 127].
• Common practice to spray a 30 cm band over the crop row after emergence which can reduce the application rate by up to two thirds [99].
• Sometimes use a top up application of atrazine (up to 1.0 kg ai/ha) in June or July [136] with glyphosate [162].

Other submissions reported on the benefits of adopting minimum tillage methods. One submission considered minimum tillage practices and the use of atrazine had revolutionised sorghum production on the farm. Other submissions supported this with reports of increased yields and decreased soil erosion (and associated benefits). Other improvements noticed were:

• No crop failures in 16 years [136].
• 0.5 to 2.0 tonnes yield/ha better than neighbouring crops [136]. Improved yields because of retained moisture [162].
• Decrease in soil erosion, and more biologically active soil, for example, more earthworms [136]. Improvement in soil structure [162].
• Increased rates of water infiltration into soil [136].

Without atrazine

If atrazine were withdrawn, submissions indicated that there would be a move back to increased tillage farming leading to increased soil erosion and greater costs. Alternatives to atrazine ranged from 'none' to 'not adequate'. Other comments on the effect a withdrawal of atrazine would have on agriculture are as follows:

• Lower crop yields through weed and grass competition. Possible contamination of the resulting grain [49, 100, 136].
• Severe economic hardship [104]. Marginal grain yielding country could become uneconomical to continue [120]. The industry has been through a difficult time with small margins. Any decrease in production now would have a severe impact on market place competition. This has implications for both State and national economies [44, 49].
• Re-organisation of weed control management strategies [104] would be necessary leading to the increased use of alternative herbicides. These are less effective and require more applications; thus more costly (2-3 x [103]), and harmful to the environment [9, 10, 30, 48, 49, 58, 102, 136]. For example:

* Phenoxy herbicides would be used at rates that can cause damage to nearby crops [99] such as grapevines, tomatoes, soybeans [5, 31] and cotton [163].

* Starane 200 (Fluroxypyr) is more expensive and has no residual properties [149].

* Many "new age" herbicides are not as effective and plants become resistant to herbicides within a short time [149].

* No alternative chemicals are available [44, 49, 123].

4.2.4.2 Grass seed

Relevance to grass seed producers

Submissions reported that atrazine is used in the production of temperate grasses such as annual and perennial rye grasses, cocksfoot, phalaris and fescues, primarily for fodder production and lawn seed [15]. Improved grasses have been developed that have major export potential [15]. Physical purity standards for domestic use and export means that other contaminating grass weeds must be eradicated [15, 30]. Atrazine is used as pre or post emergent herbicide [160] and controls unwanted grasses and weeds, particularly stipa or silver grass [137]. Low application rates are used compared to other crops, for example:

• 480 g/ha to 1.1 kg/ha [30] or 0.8 to 2.2 L/ha using boom spray units minimising possible drift to other crop areas [15], amount used depending if seedlings or established.
• 4.5 L/ha once a year for selective weed control of vigorous winter weeds during grass dormancy period [139].

Without atrazine

10 submissions emphasised the importance of producing pure grass seeds and reported that atrazine was the only chemical available to effectively control weeds. The unavailability of atrazine would result in sub-standard products because the seed crop would be contaminated with unwanted grass weeds. Many crops are produced under the government certification scheme where seed must be free of certain undesirable weed species and others must be below specified levels [15]. Sub-standard weed infested grass seed won't meet industry standards, the resulting products not saleable [7, 73, 85, 88, 160].

Atrazine is viewed as the only cost-effective chemical that effectively controls the vast array of weeds that occur commonly in seed crops [143]. Estimates were provided on the costs and detriment to the industry if atrazine were unavailable:

• Predict drop of 50 to 80% yields [21].
• Cost millions of dollars to Australian farmers [15].
• Australia exports large tonnages of seed to other countries, many of which have restrictions on weed seeds of varieties that are controlled by atrazine. This production is valued at $6 million annually [143].
• Contaminate wool and injure livestock [15].

With demand for products and expanding export market, withdrawal of atrazine would increase the amount of overseas bred varieties imported. These cost more to the user and do not persist as well as Australian bred and grown varieties [15]. They may also provide an avenue for the importation of pests [21].

Possible alternatives to atrazine were not seen as viable:

• Increase cost of mechanical cleaning which is no where near as effective or practical [15].
• Department of Agriculture in Victoria and privately funded grower organisations make continuous efforts to find alternatives, none found [15].
• No alternative in production of grasses [15, 21, 51, 73, 85, 88].

Residues

Growers providing information on residue testing reported that none had been found, either in the crop [15], waterways [73, 160] or sheep and cattle grazing on stubble between cropping [15, 22].

Improved work practices were seen as one way to decrease the possibility of residues occurring on nearby crops such as vegetables and cotton [63] and atrazine being detected in workers blood [139]. It was reported that the majority of producers already have or will soon complete the Farm Chemical Users Course which will enhance their already high levels of safety consciousness [15].

4.2.4.3 Sugarcane

Relevance to sugarcane growers

• A submission from a sugarcane growers organisation representing Australian growers [148] outlined how atrazine is used as part of farming systems within the sugar industry and commonly used as it controls a broad spectrum of weeds [47, 50, 66, 148]. One of the most important recent developments in the industry has been the development of green cane harvesting which is usually associated with the retention of the blanket of leaf material on the ground. It is not suitable for all cane growing areas but, where it is, an increasing proportion of cane is being harvested green [19, 148]. This has a number of important benefits:
• The trash blanket acts as a mulch and recycles nutrients into the soil [148].
• Slows weed growth and saves cultivation of the soil [19, 47, 148].
• Helps to prevent soil erosion and damage to the soil from rainfall impact [19, 47, 148].
• Retains moisture, allows for more growth and less irrigation [148].
• Decrease fuel use by 50% [47].
• When weeds such as vines and annual grasses do emerge, atrazine is one of the chemicals used rather than conventional cultivation [19, 148].

Atrazine is used pre-emergent at 1.5 to 3.0 kg ai/ha, once per year [119]. Sugarcane is harvested as a two year crop and uses 2.4 to 3.6 kg atrazine/ha every second year [47].

Environment

Information submitted on unpublished work by the Bureau of Sugar Experiment Stations reported that no traces of atrazine were detected in leachate from cane fields [148]. No evidence of contamination of waterways [47]. More broad scale work on catchments in the Johnson & Herbert River areas has found traces at the limit of detection [148]. Considerable work has been done at a catchment and field level on the fate of herbicides in the industry (referenced) [148].

No atrazine residues have been detected in raw sugar  [148,47] or in soil [47]. Studies show that atrazine adsorbed by the roots of sugarcane translocates to the leaves, with only small amounts remaining in the stalks. Thus, atrazine lost from the plant as leaf abscission occurs and small amount entering the mill is undetectable in molasses and raw sugar. No residues recorded in exports [34].

Current research involving atrazine is being conducted by the Queensland Department of Primary Industries which has put in place a program to examine the fate of pesticides used in the sugar industry (report expected September 1995) [148] and cane growers who have commissioned a comprehensive environmental audit of the Queensland cane growing industry; agricultural chemicals will be included [148].

The sugar industry promotes safe and responsible use of chemicals. It has sponsored Herbicide Accreditation courses in 1991 and 1995, with over half the growers attending one or both courses [47]; Pesticide Application Workshops that 70% of Queensland cane growers have received accreditation for attendance at [19] and has developed technology transfer systems which continue to promote guidelines for the safe use of atrazine [19].

Without atrazine

Atrazine used in a mix with 2,4-D which has been developed as a cost effective treatment. Loss of atrazine would increase use of phenoxy acid herbicides [19]. Atrazine is an activator of 2,4-D for weed control on young cane so lower amounts are used [50]. The use of 2,4-D has been decreased due to health concerns and diuron is now preferred as a mix with atrazine or hexazinone. Atrazine is also compatible with a broad range of herbicides, has low volatility and is least phytotoxic to young cane [19].

Alternatives to atrazine are viewed as more costly [66, 148]. Diuron is 33% less effective for the same residual effect as atrazine so higher doses are needed [50]. Other alternatives (not specified) kill a reduced variety of weeds [66, 148] are not as specific [19] or require multiple applications to be effective [66, 148].

Diuron is more soluble than atrazine and, therefore, has the greater potential to contaminate water [50]; simazine is too insoluble [80].

An alternative for the control of vines is a move back to the tillage systems [19].

4.2.4.4 Canola

Several submissions supported the use of atrazine for canola crops which is an expanding industry due to the availability of the atrazine resistant canola variety "Siren". This has resulted in an expansion of the area grown with canola [21, 41, 78, 135]. It is a fast expanding industry in Western Australia and the use of atrazine with the new atrazine resistant varieties for the control of broad leaf weeds is of great commercial benefit [115, 135]. The relatively short half life of atrazine poses no threat to the next season's crop [145].

Without atrazine, simazine would need to be used at higher rates and would pose a residues risk if the season finished dry, severely limiting crop options [145].

One grower reported that he had experimented with minimum tillage and Siren canola in rotations following faba beans, manipulated grass free pasture or unsprayed grassy pasture. The last rotation was the most successful although it is dependent on atrazine to control the weeds, barley grass and radish. Atrazine is used at seeding time at rates of 1.35 L/ha with 1.8 L/ha simazine, followed by 1.0 L/ha atrazine on the very weedy patches, eight weeks post seeding [145].

Top

4.3 Plantation forestry

16 detailed submissions were received from plantation forestry operators supporting the continued use of atrazine. The author of one submission felt it was illogical to have a distinction between plantation forestry and agriculture. The expansion of plantations in WA is on cleared farming land. This is seen as diversification and an alternative crop; therefore, no distinction [171].

4.3.1 Properties

Atrazine exhibits knock down residual activity and pre and post action [23, 39, 52, 96, 147] to control grasses and broadleaved weeds [144]. It has low phytotoxicity to eucalypts [39] and can be applied over the top of young trees without adverse effects [147]. It also enhances tree growth through the control of weeds and is a metabolic stimulant [53, 171].

Atrazine has little mobility and is safe to use in terms of Occupational Health and Safety requirements [96].

4.3.1.1 Ground dispersible granules

Granules are chosen for their ease of handling, easy clean up after spills and cheapness [53, 98, 147]. There is less drift from target areas during aerial application [53, 98, 147] and granules are more effective, providing longer lasting weed control than spray at the same application rates. This is because all granules eventually reach the soil and the chemical is more likely to be taken up by target weeds rather than moving off-site or leaching by rainfall [98].

Liquid formulations are used under some circumstances, for example, the establishment of new plantations on flat uniform agricultural land may be more cost effective with liquids [147].

4.3.2 Methods of application

Atrazine is applied as a spot application [159]; ground strip [53, 96, 159] to minimise impact on ground water; aerial broadcast [159]; via helicopter, four wheel drive motor bikes, tractor or hand operated units [39, 96]; and low volume Herbie methods [40, 144].

On second rotation sites, the weed problem is decreased by retaining and mulching logging slash after plantations are final felled. On some sites this allows strip rather than broadcast herbicide application so only half a given area receives herbicide [147].

Atrazine is used once per year to control weeds along fire-breaks. This use is conducive to low volume application (best results are obtained when the application rate is decreased by 30%) by hand spray from a tractor with the spray head not higher than 600 mm from the ground. Atrazine is preferred for its viscosity.  No noticeable damage to nearby plants has been noticed after application or after rain. The risk of inhalation is minimal as the application height is below the knee. Current label instructions for this use are inadequate and this may be because there is less experience with this use. Another label weakness is the lack of suggestions of how unused chemical can be recovered and recycled [144].

4.3.3 Uses

4.3.3.1 Establishment of plantations

Atrazine is the major preparatory herbicide for planting trees, especially during the establishment period in the first two years of growth [23, 52, 96, 53, 140, 144, 150, 159, 167, 171]. It is important to provide weed control early as weeds have a detrimental effect on the growth of the trees, and subsequent profitability [53, 142]. Benefits in growth rates achieved with atrazine are a growth response of 100% in the first year compared with untreated areas [96]. It is estimated that at least one year's [147] or at least two year's [98] tree growth is lost for each year herbaceous weeds are not controlled.

On sandy sites, broadcast weed control is required because of the competition by herbaceous weeds for soil moisture in particular [98], especially pines [147]. In WA, atrazine used on pines on all soil types and simazine is used on eucalypts on light textured soils as eucalypts have a lower tolerance for atrazine on WA sandy soils. Where possible atrazine is used because of its broad-spectrum action [171].

Atrazine may also have a stimulatory effect on tree growth. It has been suggested that up to 15% of the growth response can be attributed to increased nutrient uptake after spraying with atrazine [171].

Examples of use regimes provided in submissions are:

• Glyphosate turf break, then atrazine (low residual) then simazine (residual) are used to control a broad range of vegetative seeds in the first six months. After planting, slash and glyphosate (on tractor) and atrazine for broad leaf and grassy weeds are used [39, 96].
• Once-off application as 1.5 to 2.0 m wide strips depending on tree spacing. The minimum rotation for pine is 25 years and for eucalypts, 11 years [171].
• Once or twice in the first 18 months of establishment [147]. After that, the trees out compete the weeds.
• Once in 30 years [150].
• Apply atrazine twice in each pine crop rotation of 30 years [150]. Plantation exceeds 42 000 ha, with an annual plant of 1600-2000 ha/year.
• Used in the establishment phase since 1970s on 17 000 ha eucalypts and 4000 ha pine, about 90% ex-pastured sites [53, 144].
• Once in the plantation's life either pre/post-plant in the first year [96].

Margins are low and there is little margin for error. Establishment and maintenance costs of plantations should be below $1500/ha so the aim is to control weeds in the establishment phase and first 12-18 months [159].

Atrazine is important to Tasmanian farmers as a way to utilise marginal land, particularly in steep areas, where it allows the farmer to grow trees on otherwise unutilisable land. This has conservational merit and the trees provides wind breaks and animal shelter [23].

4.3.3.2 Firebreaks

About 20% of plantation estates will have atrazine applied annually to create firebreaks. The firebreaks of the remaining 80% will receive another pre-emergent chemical or will be graded. One submission estimated that, in 1995, atrazine consumption for firebreak maintenance of an area of 21 000 ha was a total of 1460 kg ai, an average of 0.069 kg ai/ha [140, 144].

4.3.4 Amounts used

Rates, depend on rainfall and type of soil and are reported as:

• 8 kg /ha on clay soils [150]. Lower rates not as effective.
• 2.5 to 3.5 kg ai/ha in WA, 4.5 kg ai/ha [98, 150, 147, 167] and 6 kg/ha [96] on sandy soils.
• 3.6 to 6.03 kg ai/ha. In 1995, 8400 kg atrazine used to establish 4000 ha, average 2.1 kg ai/ha [144].
• less than 4.5 kg ai/ha in a 35 year rotation [53].

4.3.5 Without atrazine

Alternatives to atrazine either do not exist or are more costly [23, 39, 52, 96, 144, 150, 167]. To achieve the same spectrum of weed control, tank mixes of multiple products and spray additives or multiple applications are required [39]. Substitutes also have some level of phytotoxicity to trees and poorer residual control [52]. Specific alternatives were mentioned in submissions, as follows:

• Terbuthylazine (Gardoprim) is used in New Zealand as an alternative to atrazine on pine but this chemical is not registered in Australia [96, 98] and is more expensive [98, 147].
• Simazine is used in preference to atrazine on areas where broadleaf weeds are expected [96].
• Hexazinone is used in plantations but is expensive (3 times that of atrazine) [96, 147] and can have phytotoxic effects if conditions are unfavourable [96]. The spectrum of weeds controlled is also narrower [147]. Hexazinone is used in eastern Australia and New Zealand, but is not used in Western Australia because it is phytotoxic to pines. It is also not favoured because of higher costs and its high leaching potential. Other residual chemicals have been assessed for use in plantations but they generally have low activity at economical rates or provide a narrow spectrum of control thus requiring tank mixing with other herbicides to achieve acceptable efficacy [171].
• Tiazopyr (Visor) is a partially effective replacement for atrazine. It is more effective on small seeded annual grasses and broadleaf weeds and usually needs to be applied in a mixture with other knockdown or residual herbicide [98].
• Glyphosate can be used but higher application rates are needed and this makes it more expensive to use than atrazine [167].

Atrazine may also play an important role in new methods of weed control. In Victoria and Tasmania, trials have been initiated using oversowing to control woody weeds. Suitable sites are planted with legumes and grasses before tree planting. After planting the trees are released from competition from the oversown species by spot atrazine application. Withdrawal of atrazine would negate this developmental approach to woody weed control in Victoria and Tasmania where trials are being conducted [98, 147]. Spot application decreases the area treated per hectare (example of calculation provided).

In terms of specific costs, alternatives are 3 [23, 96] to 10 [39] times more expensive and can add $184/ha per year to total costs [144]. The whole of the South Australian pine plantation industry could lose up to $38 million from each year's planting without access to atrazine [164]. Manual methods of weed control are possible but are estimated to cost around $1000/ha [98].

4.3.6 Public health and water

Employers report no health problems, with worker safety a high priority [53]. Atrazine is safe to use under occupational healthy and safety requirements [96, 140]. In over 30 years, no evidence of adverse health or environment effects has been documented [171].

No complaints have been received from trout hatcheries, which operate on rivers where catchments include atrazine-treated plantations [96].

Before treatment, soil type, application rate, soil moisture, run off and buffers around water courses are examined to assess the potential for water contamination [53]. Several examples of sampling regimes before and after treatment were provided [96, 144]. One operator reported that, in 1994, atrazine levels never rose above the Australian Drinking Water Guidelines at any domestic water intakes downstream of operations. Another reported that atrazine was present in detectable amounts. In sandy soils the concentration of atrazine was higher than the WHO level of 2 ppb, during mid-winter when streams were in peak flow. In early spring, of the first year of establishment, all sites had levels below 2 ppb and did not approach these concentrations in subsequent years when only the firebreaks were sprayed [144].

Sampling of streams showed that off site movement of atrazine was related to significant rainfalls (>10 mm). Factors minimising contamination were:

• small coupe sizes relative to catchment area
• strip spraying (less atrazine used, unsprayed portions act as buffers to decrease cross surface flow of water)
• stream buffers
• application by ground based spraying equipment [171].

Data collected in WA (1990 and 1991) found that while there is potential of atrazine to move out of target area in surface run-off, there is a negligible chance of detections above the level of determination [171].

In Tasmania, all applicators are trained in the handling, storage and application of pesticides. They are also required to be registered pesticide applicators under the Tasmanian Pesticides Act and to have passed a training course such as the National Farmers Chemicals Training Program of Avcare [96].

Submissions on two cases of atrazine water contamination which gained media attention in Tasmania were received [159]. One occurred in North West Tasmania, where surface water ponded over a portion of plantation area in mid winter rain and may have subsequently entered a stream. The other occurred in North East Tasmania where very high levels of atrazine were recorded immediately adjacent to the spray area. The level of contamination dropped rapidly over a short period of time [159].

Other comments in the plantation forestry submissions considered it premature to make decisions on atrazine when the review of non-agricultural uses still is under way by the Forest Herbicide Research Management Group[167], a group established with plantation forestry involvement to look into environment effects [53]

Top

4.4 Suggested outcomes

Comments on the possible outcome of the current review of atrazine ranged as follows:

• Diversity of use and the role of chemicals in each agricultural and horticultural industry needs to be recognised and examined when the findings of the evaluations are undertaken [21].
• Atrazine should be deregistered [1, 134d] and replaced by non-polluting means of weed suppression [1].
• Aerial spraying should be banned [97, 125].
• More site restrictions on use should be considered [97].
• No more off-label permits should be issued [97].
• If the results of the review are based on scientific information the use pattern should be altered to accommodate acceptable limits before withdrawal of atrazine is considered [23, 24].
• Atrazine should be retained [9, 31, 3, 54, 64, 132] for use on maize, sweetcorn, grain sorghum. Atrazine should be registered for use on corn/sweetcorn with "Dual" (metalochlor), and research initiated into the most environmentally acceptable ways of applying atrazine either alone or in combination with metolachlor [5].
• Current labeling should be maintained [47].
• Usage rates for channel weed control are quite high (~70 kg/ha). Exclusion of this use will reduce the potential for localised ground water contamination. Usage rates on crops should be dropped to a maximum of 3 kg ai/ha. This submission also highlighted that labeling changes to atrazine are not well known about by farmers and suppliers and that no suppliers had received atrazine with revised labels [170].

4.5 Atrazine survey

The NRA also surveyed various groups involved as advisers, users and registrants of atrazine to gather information on use, performance, changed agricultural practices, adverse effects and trade and residues. This was done by sending out Performance Questionnaires on atrazine. The results from these form part of the efficacy and other reports which appear in later sections.

5. CHEMICAL AND PRODUCT DETAILS

5.1 History of registration

Atrazine was reported and developed in the late 1950s. It was first registered across Australia (registrant Ciba-Geigy) in 1960-61 for the control of annual weeds and seedling grasses in broadacre crops such as maize, sweetcorn, broom millet, sachalline, and non-agricultural situations such as along fence lines, irrigation channels, drains, driveways and footpaths. Registration was later extended, in 1977, to include the control of weeds around pine seedlings.

The toxicology of atrazine was first considered by the National Health and Medical Research Council (NH&MRC) of Australia in 1985. The toxicology of atrazine has been evaluated and reviewed by the NH&MRC on a number of occasions since then.

Maximum Residue Levels (MRLs) were established for corn, grain and fodder, sorghum, broom millet and established lucerne and sweetcorn in 1983-84. An experimental MRL in cereal grains was also established at that time.

The issue of atrazine use and water contamination was investigated by the NRA in 1993 and resulted in a set of amendments to use patterns, including buffer zones from water courses, dams and wells, and maximum application rates. Previous uses in non-crop situations such as fencelines, rights of way and irrigation channels were discontinued at the end of December 1995 because of concerns for aquatic contamination. These discontinued uses generally involved much higher rates of application in situations conducive to off target movement to water.

Another outcome of the 1993 investigation was the establishment of the Forest Herbicide Research Management Group The role of this group was and is to plan and review a water monitoring program and a series of trials on the impact of various atrazine use patterns on water quality. Interim recommendations from the Group are expected in 1997 with final recommendations by 1998/99.

More details of the NRA action, including the establishment the Forest Herbicide Research Management Group, are contained in the efficacy section of the Agricultural assessment.

5.2 Use pattern

Atrazine is a selective systemic herbicide which provides knockdown and residual action. It is mainly absorbed through the roots, then transported to the actively growing tips and leaves where it inhibits photosynthesis and interferes with other enzymatic processes in the plant to produce yellowing and death. Atrazine is used before and after the emergence of weeds to control some annual grasses and most broad-leaved weeds in a variety of crops and plantation forestry.

Atrazine is toxic to many crops, including most vegetables, potatoes and soya beans. Crops which are not tolerant to atrazine, should not be planted until the area is free of atrazine residues.

In Australia, atrazine is registered in 34 products and 4 Technical Grade Active Constituents (TGAC), produced by 14 companies. Atrazine products are available as liquids, granules, wettable powders and water dispersible granules. It is formulated alone and in combination with other herbicides such as ametryn, amitrole, hexazinone, metalochlor and dicamba.

Atrazine is one of the most widely used herbicides in Australian agriculture (estimated tonnage, a few thousand tonnes per annum). Major agricultural uses in Australia include summer crops such as sorghum and maize. It is also used on sugarcane and is widely used in Western Australia on lupins. Use on triazine-tolerant canola is a new, rapidly increasing use, allowed under NRA permit. Minor uses include lucerne, grass seed, pasture and potatoes. Off-label uses include chickpeas and faba beans. Main non-agricultural uses are in the establishment of pine and eucalypt plantations (the major use occurring in Tasmania) and Parthenium weed control in Queensland, parts of the Northern Territory and northern NSW. In the home garden, atrazine is used in areas such as driveways, footpaths, fencelines, paved areas and tennis courts.

Currently approved labels for products containing atrazine contain recommendations for use on the following crops:

Atrazine is also used for weed control in conservation tillage farming systems, for seed bed establishment prior to planting sorghum, or for fallow maintenance prior to wheat, peas or lupins.

5.3 Application methods

Atrazine is applied as a coarse spray either pre- or post-emergence.  The exception is potatoes, where atrazine is used as a harvest aid after the crop has matured. In general, ground based application predominates, but aircraft are commonly used in fallow situations and sugarcane, and helicopter application is widely used in plantation forestry.

5.4 Formulation

Atrazine technical grade active constituent is not manufactured in Australia, being imported from the United States, Switzerland, Italy, South Africa and Israel.

5.5 Packaging

Container sizes for liquid products include 5L, 20L, 200L and 1000L.  The granular product is a 20 kg bag. The wettable powder is in 2.2 kg and 25 kg lots and the water dispersible granules are in 2.2 kg, 10 kg and 15 kg lots. Container sizes for home garden products include 100g, 200g and 1L packs.

Top

6. OVERSEAS REGULATORY STATUS

Atrazine is registered in many countries around the world, including the USA and the European Union, but with various restrictions such as reduced application rates in the USA.  Some EU member States have discontinued the use of atrazine because of its widespread presence in water.  Atrazine and the closely related herbicide simazine are presently under special review in the USA because of concerns associated with their presence in drinking water and possible carcinogenic properties (US EPA, 1994)".

The US EPA announced a special review of the triazine herbicides in November 1994, apparently arising from concerns from speculated links to breast cancer incidence.  In the USA where atrazine was first registered in 1958 or 1959, it is estimated that 90-120 million lbs of triazines are used each year, with atrazine accounting for up to 80 million lbs of that (mainly in corn).  The concern is that atrazine is contaminating drinking water because of its relative stability and mobility in soil.  However, there has been a "massive" response to the US EPA from farmers and farmers federations who claim that atrazine is safe, cheap and effective.  Ciba-Geigy suggested that economic losses in agriculture could range from US$1.2 to US$2.8 billion.  DuPont Agricultural products has agreed to completely phase-out the related triazine, cyanazine, by the end of 1999.

It has been reported that atrazine has been banned in Germany (March 1991), Italy (temporarily in 1990; extended in 1991), Norway and Sweden.

UK evaluations of atrazine are available, prepared by the Pesticides Safety Directorate of the Ministry of Agriculture, Food and Fisheries (MAFF); these assessments, dated May 1992 and July 1993, were initiated following the identification of concerns about the fate and behaviour of the triazine herbicides in soil and water. The proposed environmental quality standard (EQS) in water was 2 g/L based on the annual combined average of atrazine and simazine, with a maximum allowable concentration (MAC) of 10 g/L for atrazine and simazine combined.  UK Water Supply (Water Quality) Regulations 1989 require levels of individual pesticides in drinking water at the tap to be less than 0.1 g/L.  It was recommended that the use of atrazine be permitted on cropped land but not on non-crop land (industrial or amenity situations, fallow, wasteland, footpaths, roads, tennis courts etc.), that it not be aerially sprayed, and that application on crops not exceed a set maximum rate per year. Home garde use was considered acceptable.

Atrazine was reviewed by the International Agency for Research on Cancer in 1991 (IARC, 1991).  It was classified in Group 2B (possibly carcinogenic to humans).

ATTACHMENTS

Attachment 1: Breakdown of public submissions received on the NRA Review of Atrazine, by category:

Back to atrazine review