Media Release - Commonly used toilet deodorant chemical not a concern


03 Aug 2000

The National Industrial Chemicals Notification and Assessment Scheme (NICNAS) released for public comment today a draft report on the hazardous industrial chemical, para-dichlorobenzene. The report concludes that the use of the chemical is well controlled at present and unlikely to cause any harm to people or the environment in Australia.

Para-dichlorobenzene is widely used as a deodorant in public toilet facilities, including those in schools. The chemical is also available to the public for use in homes were it is used as a toilet deodorant, an air freshener and to protect clothes from damage due to moths and silverfish.

Total annual imports of the chemical into Australia amount to between five hundred and one thousand tonnes, most of which is imported by three companies. The chemical is processed into small blocks or disks prior to packageing for distribution to commercial cleaning suppliers or retailers to the public. The chemical is volatile and works by producing a vapour that masks odours. At high concentrations the vapour may cause irritation to the eyes and nose of some individuals. The handling and processing of para-dichlorobenzene was found not to constitute a risk to those employed in the industry. Concerns that the chemical, an organochlorine, may produce cancer in humans were investigated but, after careful evaluation of the data available, were found to be unwarranted.

Para-dichlorobenzene is widely available to the public through supermarkets and general stores. Products containing the chemical are typically greater than 90% para-dichlorobenzene. The NICNAS assessment found that, when used according to the instructions on the package, the chemical should not constitute a risk to the public.

Although para-dichlorobenzene is released to the environment, it is broken down quickly and is not expected to cause harm to living organisms.

The contact at NICNAS for free copies of the draft report and public submissions is Dr Michael Muller on phone (02) 9577 9473 or email mullerm@ASCC.gov.au. Submissions must be received within the next 28 days.

MEDIA: For further information please contact Nick Miller, Communications Manager, NICNAS, on (02) 9577 9349.

Para-Dichlorobenzene: Draft Report for Public Comment - Summary



Para-dichlorobenzene was declared a Priority Existing Chemical on the 7 April 1998. The declaration of para-dichlorobenzene was in response to concerns relating to possible human health risks and environmental hazards associated with the widespread use of the material in school and public toilet facilities and as a domestic air freshener.

Import and use

Up to 1000 tonnes of para-dichlorobenzene are imported and used annually in Australia. Para-dichlorobenzene is primarily used as a deodoriser in public toilet facilities, in household toilets and as a room freshener in addition to some minor uses in the agricultural and pharmaceutical industries.


Para-dichlorobenzene is readily adsorbed by inhalation and oral routes and less well by dermal contact. Target organs for para-dichlorobenzene are adipose tissue, liver, kidneys and lungs. The parent compound and its metabolites are rapidly excreted in the urine. There is no evidence that para-dichlorobenzene bioaccumulates in tissues.

Acute exposure to para-dichlorobenzene vapour within the range of 30 to 60 ppm in air is associated with irritation to the nose, eyes and upper respiratory tract. Exposure to vapour of 80 to 160 ppm results in acute discomfort, painful irritation of the nose and eyes and may induce breathing difficulties. Ingestion of large doses of para-dichlorobenzene have been associated with vomiting, vertigo, disorientation, tiredness, oedema and conversion of haemoglobin to methemoglobin. Chronic exposure to high doses of para-dichlorobenzene may result in headache, nausea, vertigo, ataxia, dysarthria, hyporeflexia, paresthesia, behavioural and haematological changes including anaemia.

Genotoxicity studies of para-dichlorobenzene have produced negative results. However, para-dichlorobenzene does induce the formation of kidney tumours in male rats and liver tumours in both sexes of mice after prolonged exposure. The formation of kidney tumours in male rats is thought to be due to the presence of the protein, a2m-globulin. As a2m-globulin is specific to the mature male rat, para-dichlorobenzene is not considered to present a carcinogenic risk to humans by this mechanism. The tumours observed in mice after prolonged exposure to para-dichlorobenzene are also considered to be irrelevant to humans. There are significant differences in the metabolism of para-dichlorobenzene in the liver of mice and humans and it has been further observed that the mouse strains used demonstrate a high natural rate for liver tumour formation.

Exposure of pregnant rats to para-dichlorobenzene vapour produced no evidence of maternal toxicity or embryo-, foeto- or teratogenicity.

Occupational health and safety

The occupational risk assessment for para-dichlorobenzene concluded that, for known Australian work situations, potential atmospheric concentrations of para-dichlorobenzene are unlikely to reach levels likely to cause acute effects, including eye or respiratory irritation. In addition, it is unlikely that workers in these occupations will be at risk from chronic adverse health effects related to para-dichlorobenzene exposure, as margins of exposure are generally high for inhalation exposure. In the absence of any monitoring data for workers involved in the hygiene sector estimates for para-dichlorobenzene exposure were obtained using the known physical properties of the chemical and computer modelling. Results from this modelling indicate that the risk to workers is expected to be low.

Public health

Public exposure will principally arise from the use of para?dichlorobenzene in toilet deodorant blocks and air fresheners. Public exposure will occur principally by inhalation, with the potential for dermal exposure reduced by the containment of para-dichlorobenzene in cellophane wrapping during handling. There have been no confirmed reports of skin irritation or sensitisation in widespread human use. Consequently the risk of dermal irritation or sensitisation is considered to be low.

Investigations of the airborne concentrations resulting from the use of para-dichlorobenzene as a household air freshener or as an insect repellent in wardrobes indicate that concentrations are likely to be well below those where irritation or chronic effects may be observed. The risk to the public from the intended use of para?dichlorobenzene in the household or public toilets is considered to be low.


Environmental exposure to para-dichlorobenzene can occur due to the use of the product in toilets from which it may be washed into the sewer system or enter the atmosphere by virtue of its volatile nature. Para-dichlorobenzene does not persist in air or surface water but accumulates in anaerobic sediments. Para-dichlorobenzene has a medium acute toxicity for aquatic life and may impair the reproduction of aquatic life. However, based on current patterns of para-dichlorobenzene use within Australia, the risk to the environment is expected to be low.


Recommendations for reducing potential occupational health and safety risks for para-dichlorobenzene include the monitoring of airborne para-dichlorobenzene to be undertaken and a review of the current occupational exposure standard for para-dichlorobenzene by the National Occupational Health and Safety Commission.

The hazard classification should be amended to include the follows safety phrases, S23 (Do not breath vapour), S24 (Avoid contact with skin), S25 (Avoid contact with eyes) and S51 (Use only in well ventilated areas).


The National Industrial Chemicals Notification and Assessment Scheme (NICNAS) operates under the Commonwealth Industrial Chemicals (Notification and Assessment) Act 1989.

NICNAS is a statutory scheme within the portfolio of the Minister for Health and Ageing. Its approach to the scientific assessment of chemicals covers toxicity, exposure and use to assess the environmental, public health and occupational health and safety risk. For more information see the web site www.nicnas.gov.au

Further information

Nick Miller, NICNAS, (02) 8577 8810 or 0407 228 285