Leaks and Spills

Primary reference(s)

WHO, no date. Chemical incidents. World Health Organization (WHO). Accessed 14 February 2025

Annotations

Key relevant UN convention / multilateral treaty

While a single global treaty specific to chemical leaks and spills doesn't exist, several international frameworks contain relevant provisions:

• Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal (1989). At the time of writing, there were 187 parties to the Basel Convention. At its 14th meeting, the Conference of the Parties to the Basel Convention adopted decision BC-14/12 by which it amended Annexes II, VIII and IX to the Convention with the aim of enhancing the control of transboundary movements of plastic waste and clarifying the scope of

Regional Directive: Europe example: Directive 2012/18/EU of the European Parliament and of the Council of 4 July 2012 on the control of major-accident hazards involving dangerous substances, amending and subsequently repealing Council Directive 96/82/EC Text with EEA relevance, Applies to European Commission Member States (European Parliament and Council, 2012). In Europe, the catastrophic accident in the Italian town of Seveso in 1976 prompted the adoption of legislation on the prevention and control of such accidents. The so-called Seveso-Directive (Directive 82/501/EEC) was later amended in

Drivers

Leaks and spills can occur due to natural hazards, industrial accidents, or infrastructure failures, and they often create cascading risks. Several hazardous chemicals can be released during leaks and spills incidents, leading to different impacts.

Impacts

These incidents can trigger or worsen multiple hazards. They generally affect environmental health, human health or both. Air, water and soil pollution leading to environmental degradation and biodiversity loss are often observed. Damages to health vary depending on the chemical release but include skin damage, eye damage, respiratory issues, sometimes leading to death, either immediately after the event, or sometime later

Multi-hazard context

The figure below summarises common interactions between leaks & spills and other hazards. This information should be used with caution and not be solely relied upon in Disaster Risk Management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify, or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above.

Multi-hazard diagram

Risk Management

Risk management measures can be grouped under the categories: prevention and control, preparedness and response. 

Prevention and control: Being aware of chemical incident- related hazards: locating chemical sites away from centres of population; registration of all chemicals in commercial establishments with a hazard inventory to ensure rapid identification of the released chemical; regular evaluation of plans and their implementation; inspection/monitoring, and enforcement of safety measures; reducing the amounts of chemicals stored; appropriate labelling of all chemicals; conducting response drills; rapid notification of the chemical incident emergency services in the event of a chemical release; regular surveillance and standardised reporting of incidents, including the small, commonly occurring incidents; measures to decontaminate land or water already contaminated by waste disposal; measures to prevent or contain any fire-fighting water run-off; and construction of drainage ditches or holding tanks to contain liquid chemicals (WHO, no date; UNEP/OCHA, 2023). 

In any chemical incident, there are a number of essential steps to go through as part of the chemical incident plan. These steps include alerting the emergency services; assessment of actions and management options; environmental monitoring; public information and public warnings; advice on protection; sheltering or evacuation; other interventions to protect public health; and organising registers and samples as required (WHO, no date; National CBRN Centre, 2016; UNEP/OCHA, 2023). 

Preparedness: Careful planning and thorough preparedness are prerequisites for an effective response to chemical incidents. Public authorities, at all levels, and the management staff of installations where hazardous chemicals are produced, stored etc. should establish emergency preparedness plans. All responsible parties should ensure that manpower, equipment, and financial and other resources necessary to carry out emergency plans are readily available for immediate activation in the event, or imminent threat of an accident. In addition, all personnel involved in the emergency response process should be adequately educated and trained (WHO, no date; National CBRN Centre, 2016; UNEP/OCHA, 2023). 

Response: Depending on the type of contaminant and if an acute or a chronic contamination incident and the level of potential exposure from chemical leaks and spills consider, if appropriate, setting up risk zones. These are usually established around an incident: 

• The hot zone is the area where first responders must use protective equipment to prevent primary contamination and is the area with actual or potential contamination and the highest potential for exposure.
• The warm zone, which surrounds the hot zone, is the area where appropriate personal protective equipment must be worn to prevent secondary contamination. The warm zone is an area uncontaminated by the initial release of a substance, which becomes contaminated by the movement of people or vehicles. The warm zone will be extended to include the area of decontamination activity. These areas cannot be guaranteed as free from contamination.
• The cold zone is the uncontaminated area between the inner cordon and the outer cordon where it has been assessed that there is no immediate threat to life.
• The decontamination line separates the warm zone from the cold zone, which is the area free from contamination (National CBRN Centre, 2016). 

Consider contacting the nearest Poisons Centre in case advice on diagnoses and treatment of chemical poisonings is needed. Also consider setting up a public health team which, in the case of a spill-related chemical incident, will provide accident and emergency departments with information about the nature of the chemicals(s), any precautions to be taken, and information about secondary contamination and how to decontaminate casualties, staff and equipment. Further details and guidance can be found in the WHO manual on the public health management of chemical incidents (WHO, 2009). 

Designed to help manage the recovery phase of a chemical incident where contamination has affected food production systems, inhabited areas and water environments, further information can be found in the UK recovery handbook for chemical incidents (PHE, 2020). 

Community-based monitoring programs represent an important complementary approach to institutional and technological monitoring systems. Local communities often detect early warning signs of leaks through observations of environmental changes like unusual odours, water discolouration, or vegetation stress. Establishing formal mechanisms for community reporting, combined with training on basic observation protocols, can create valuable distributed monitoring networks. These approaches are particularly important in regions with limited institutional capacity or remote areas where technological monitoring coverage may be incomplete. 

Guidance on risk communication strategies during a chemical leak and spill incidents should be effective, transparent, and timely communication is essential for reducing public exposure, maintaining trust, and facilitating cooperation with protective measures. Risk communication should be tailored to different stakeholder groups, address scientific uncertainties honestly, and incorporate cultural factors affecting risk perception. The WHO's Emergency Risk Communication guidelines provide valuable frameworks to help authorities manage the critical information dimensions of chemical leak and spill events (WHO, 2017) 

The World Health Organization (WHO) works closely with countries and partners to monitor and report on their emergency preparedness capacities for all hazards, including chemical incidents. Surveillance of diseases of possible chemical aetiology is a daily element in the WHO outbreak alert and response activities (WHO, no date). The WHO also convenes regional meetings to strengthen the global network of poison centres and thus facilitate emergency responses to chemical incidents. Guidance and training materials to strengthen preparedness for chemical incidents and emergencies have been developed in collaboration with the Organisation for Economic Co-operation and Development, the Inter-Organization Programme for the Sound Management of Chemicals, and relevant organisations in the United Nations system (WHO, no date). Additional resources include the WHO human health risk assessment toolkit for chemical hazards (WHO, ILO and UNEP, 2011) and the guidance document on evaluating and expressing uncertainty in hazard characterisation (WHO and IPCS, 2018). 

Monitoring

The section and the table below offer an overview of monitoring arsenic. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency/authority responsible for disaster management.