Leaks and Spills

Primary reference(s)

WHO, 2020. Chemical incidents. World Health Organization (WHO). Accessed 23 October 2020.

Additional scientific description

Three notable examples of technological incidents involving a chemical leak and/or spill are the Seveso chemical leak, the Bhopal chemical leak and the Exxon Valdez oil spill.

Seveso chemical leak: At approximately 12:37 on Saturday 10 July 1976, a bursting disc on a chemical reactor ruptured at the Icmesa chemical company, Seveso, Italy. Maintenance staff heard a whistling sound and a cloud of vapour was seen to issue from a vent on the roof. A dense white cloud, of considerable altitude drifted offsite. Among the substances in the white cloud was a small deposit of 2,3,7,8-tetrachlorodibenzo-p-dioxin (‘TCDD’ or ‘dioxin’), a highly toxic material. The release lasted for twenty minutes. Over the next few days there was confusion due to the lack of communication between the company and the authorities in dealing with this type of situation. The nearby town of Seveso, located 15 miles from Milan, had 17,000 inhabitants. No human deaths were attributed to TCDD but many people fell ill. Thousands of animals in the contaminated area died and many thousands more were slaughtered to prevent TCDD entering the food chain (HSE, no date).

Bhopal chemical leak: On 3 December 1984, more than 40 tons of methyl isocyanate gas leaked from a pesticide plant in Bhopal, India. The gas drifted over the densely populated neighbourhoods around the plant killing thousands of people immediately. The leak also had long-term effects on health, with estimates of over 15,000 people killed in the years following the leak. This event highlighted the need for enforceable international standards for environmental safety, preventative strategies to avoid similar accidents and industrial disaster preparedness (Broughton, 2005).

Exxon Valdez oil spill: On 24 March 1989, the oil tanker Exxon Valdez ran aground on a charted rock, Bligh Reef, in Alaska’s northern Prince William Sound. More than 11 million litres of crude oil spilled, eventually polluting over 30,000 km2 of coastal and offshore waters (Peterson et al., 2003).

Technological incidents such as chemical spills and leaks can be sudden and acute, when hazardous chemicals are ‘overtly’ released into the environment. Some chemical leaks and spillages may also result in fires, explosions and contamination of land. The factors leading up to an incident include poor maintenance of manufacturing and storage equipment, lack of regulation and/or poor enforcement of safety regulations, road traffic accidents, human error, natural events such as heavy rain, earthquakes, hurricanes, floods, and terrorism (WHO, no date).

Chemical spills and leaks are one of the issues addressed by the Food and Agriculture Organization of the United Nations (FAO). They report that spills and leaks from containers are a major problem in the storage and transport of pesticides. The main cause of these spills and leaks is rough handling which dents drums, weakens or splits seams and weakens closures (lids, caps, stoppers). Leaks also result from corrosion of the container, which may be accelerated by mechanical damage (dents may rupture drum linings). Corrosion may start internally, with the pesticide itself or its breakdown products being the primary cause. Alternatively, corrosion may begin externally, due to rusting in damp storage conditions or contamination from chemicals leaking from nearby containers. Rodents may damage paper, board or fibre containers. Termites may attack paper and card. Pesticides should be repacked in containers made of the same materials as the original containers because some chemicals are not compatible with different materials (FAO, no date).

Most chemical spill-related technological incidents occur at the interfaces between transport, storage, processing, use, and disposal of hazardous chemicals, where these systems are more vulnerable to failure, error or manipulation. Exposure levels will in general be quite different for different people involved in a chemical incident (WHO, no date):

• Employees and other on-site persons: usually more than one exposure pathway, often inhalation (breathing) of smoke and vapours and skin contact from splashing and clean-up of chemicals.
• Emergency services: usually close to the emergency and involved in rescue, containment of chemicals, managing the impact of chemical spills; primary and secondary contamination of fire officers, ambulance officers, other emergency staff; secondary contamination of medical staff and other hospital patients of incomplete decontamination of casualties.
• Public: exposure via air, water, food, soil etc.

Metrics and numeric limits

Not available.

Examples of drivers, outcomes and risk management

Factors that affect the vulnerability of responders and the general public to a leak or spill include the nature of the hazard, the level of exposure, availability and quality of shelter, availability of personal protective equipment (PPE), access into and out of the site, the degree to which employees and responders (and possibly the general public) are prepared and trained to deal with a chemical release and the amount of training provided. Vulnerability can be reduced by ensuring that information is available on: the incident; measures being taken to contain the release; who is currently under threat; what the health effects might be from exposure; what the public can actually do to protect themselves; and how to get further information; when, where and how it will be available (WHO, no date).

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; 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). 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).

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).

Response

Depending on 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 the 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).

The World Health Organization (WHO) works closely with countries and partners to monitor and report on their emergency preparedness capacities for all hazards, including for chemical incidents. Surveillance of diseases of possible chemical etiology is a daily element in the WHO outbreak alert and response activities (WHO, 2020).

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 organizations in the United Nations system (WHO, 2020).

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 characterization (WHO and IPCS, 2018).