User:ZZZXS/Chemical safety

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Chemical safety includes practices, policies, and procedures aimed at minimizing exposure risks to hazardous chemicals across various settings from manufacturing sites to homes. It distinguishes itself from process safety, which is broader industrial hazards, by focusing specifically on preventing dangerous chemical interactions and accidents. Chemical safety covers the entire lifecycle of chemicals—from production and transport to use and disposal, and emphasizes both immediate and long-term health impacts. Key risks include the potential explosiveness, flammability, and toxicity of chemicals, which can pose significant hazards to life and the environment. Effective management and control of chemical safety are achieved through legislation and regulations about the safe handling, storage, and disposal of chemicals. These measures are crucial in protecting individuals, communities, and the environment from the harmful effects of chemical exposures.

Risks and hazards
The hazardous nature of chemicals can increase when they are mixed, exposed to heat, or handled improperly. Significant incidents of chemical exposure often occur outside controlled environments such as manufacturing plants or laboratories, leading to serious health risks. It is estimated that 1.6 million human deaths occur each year from contact with hazardous chemicals and that in 2016, 45 million disability-adjusted life-years were lost, a significant increase from 2012. The number of people who died with chemical increase year by year. Chemicals in use in industry and research have a range of properties which cause them to be hazardous to life. These include explosiveness, flammability, toxicity, carcinogenicity and teratogenicity. Chemical burns occur when skin or other tissues come into contact with a corrosive substance, such as acids, alkalis, oxidizers, or certain organic compounds. These burns can result from both direct contact with the chemical, such as NaOH + H2SO4 → Na2SO4+H2O. Any one chemical or mixture may exhibit several of these properties.

Toxic materials may be solids in powdered or finely divided form, liquids or gases and any of these materials may all be absorbed by inhalation, directly through the skin of by contact with mucous membranes in the nose or eyes. Some chemicals may persist in the body for substantial periods and can continue to exhibit toxicity. Examples of such materials include mercury, arsenic, dioxins and many organic solvents which can be stored in fat cells.

Environmental risks may be difficult to evaluate and may take years to become apparent. The risk to the Earth's ozone layer (O3) from the release of CFCs required the investigative powers of scientists throughout the world to understand fully. The oxygen will decompose to O first under the light and react with O2 to form O3. Science is still working out the seriousness of the effects of persistent halogenated organics on the marine food chain with some of these chemicals becoming concentrated in the fatty deposits of top predators in concentrations that appear to effect their reproductive success.

Management and control
There is a difference in chemical safety between richer and poorer countries is mainly about the rules in place, the availability of resources, education on safety, and how well safety laws are followed. Rich countries have strict safety rules and the resources to enforce them, including good safety gear and training for workers. Poorer countries often struggle with weaker safety rules, less access to safety equipment, and fewer opportunities for worker training. This means workers in these countries face more risks. However, discussions on this topic also point out that some poorer countries are finding smart ways to improve safety despite these challenges. They get help from international organizations and learn from success stories where safety has been improved. This shows that even with fewer resources, progress in chemical safety is possible through the cooperation.

Chemical safety is managed through laws in the Western world and Australasia. Different places have different rules: Europe uses detailed laws, while the US uses a mix of federal and state laws. Examples from these areas are described below.

European Union
The Chemicals Agents Directive, a daughter directive of Directive 89/391/EEC, provides the framework for managing chemical safety. The European Chemicals Agency is the responsible agency and specifically implements Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), sets the standards and ensures compliance across the European Union. The European Chemicals Agency sits under REACH and manages the technical and administrative aspects of the implementation of the Directive.

New Zealand
The administrative framework is based on Health and Safety at Work (Hazardous Substances) Regulations 2017 and is implemented and enforced by Worksafe, a government agency. Although this legislation is comprehensive in its coverage it does not extend beyond the workplace and imposes no duties or responsibilities in regard to hazardous materials in domestic or educational establishments.

United Kingdom
In the UK legislation to address chemical safety has been incorporated in many pieces of legislation from the early factories acts onwards. The current Health and Safety at Work etc. Act 1974 provided an all encompassing piece of legislation which covered chemical safety amongst a wide range of other measures designed to improve the safety in the workplace in the UK.

Enforcement of chemical safety is the responsibility of the Health and Safety Executive (HSE), which implements relevant sections of the Health and Safety at Work etc. Act 1974, formulates regulations, provides safety advice and guidance and investigates major chemical incidents.

United States of America
In the US, the U.S. Chemical Safety and Hazard Investigation Board is responsible for investigating major chemical accidents and making recommendations to mitigate such events in the future.

Manufacturing
The manufacture and purification of chemicals can involve a range of reagents which may themselves be hazardous, and a range of products which equally may be hazardous. For example, in order to produce the herbicide 2,4,5-Trichlorophenol, chlorine, an acutely toxic gas, is reacted with phenol, a hazardous organic liquid. The output is typically a mixture of chlorinated organic compounds, only some of which are the desired product. In this example, contaminants can include 2,3,7,8-tetrachlorodibenzodioxin, a dioxin, one of the most toxic synthetic chemicals known which is both acutely and chronically toxic and teratogenic and whose use on one occasion led to the abandonment of the Times Beach, Missouri. This reaction was also the cause of the infamous Bhopal disaster, during which the highly poisonous gas methyl isocyanate was released.

Major chemical accidents (and events that have the potential to escalate to major accidents) are covered in the specialized domain of process safety.

Laboratories
Laboratories in schools, university, research establishments and manufacturing typically store and handle a wide range of chemicals. Safety standards for such areas are high and most laboratories provide specific infrastructure to minimise risk including fume cupboards, impervious and inert work surfaces, emergency shower stations and strict policies on the wearing of appropriate PPE.

Domestic use
There are many hazardous chemicals in routine use in the domestic environment including cleaning agents such as bleach and caustic soda. Some modern cleaning formulations also contain sodium silicate and other highly alkaline components. Modern packaging into "pods" may increase the risk of misuse, particularly for small children.

Waste disposal
Surplus hazardous materials often reach the waste stream, whether by being placed in the solid waste stream or being flushed away down sinks, basins or toilets. Although dilution may reduce the immediate risk, the long term environmental risk remains and can be made more serious as more hazardous materials are disposed of in the waste water stream. Disposal with solid waste poses risks to those handling the waste and may pose unexpected risks to uninformed members of the public. Some industrial waste chemical dumps have been known to spontaneously ignite, years after the waste had been deposited. Aluminium dross processing can produce a flux-rich waste that evolves ammonia gas if wetted, and can also spontaneously ignite when stored in bulk.

Personal protective equipment (PPE)
Basic chemical safety practice includes wearing protective personal protective equipment such as safety goggles. Personal protective equipment alone does not provide sufficient protection from the risks posed by hazardous chemicals but it helps minimize the risk of exposure in controlled environments. Safety googles are required when handling chemicals to prevent chemicals from getting into the eyes. Wearing standard gloves, closed-toed shoes, long trousers, and laboratory coats to protect the stomach, back and forearm is usually required in laboratories, with similar provisions for other workplaces. Regulation of use of PPE is varies by country.

Labelling
For most of the world, a standard set of illustrative pictograms have been adopted to indicate where hazards exists and the type of hazard present. These pictograms are routinely displayed on containers, transport vehicles, safety advice and anywhere where the material occurs. These have been extended and standardized as the Globally Harmonized System of Classification and Labelling of Chemicals and are now used throughout much of the world.

In the U.S., an NFPA diamond is used to identify chemical hazards such as flammability, corrosivity, toxicity, and reactivity. This label is made up of four colour-coded fields: red (flammability), blue (health hazard), yellow (chemical reactivity), and white (special hazard). The numbering ranges from 0 to 4 (for colours except white), with 0 meaning there is no potential hazard and 4 indicating the chemical is extremely hazardous.

Material safety data sheets (MSDS)
Manufacturers provide a material safety data sheet (MSDS; also 'safety data sheet', SDS) for each hazardous chemical they produce. MSDSs are typically used and affixed by regulation at worksites handling those chemicals. An MSDS includes workplace health aspects, restrictions, emergency numbers, and other safety information.

Transportation
In a number of countries, the Hazchem system is used whenever a potentially hazardous cargo is transported whether by road, rail, sea or air. A standardized Hazchem sign affixed on the vehicle provides details of the material being transported, the nature of the hazard and the approved emergency response.

Storage
Chemical storage is crucial for preventing accidents, health, and protecting the environment. Storing chemicals by compatibility is a good way to avoid dangerous reactions (such as strong base react with strong acid), ensuring all containers are clearly labeled with essential or necessary information such as the chemical's name and hazards, and using containers that are compatible with the chemical's properties to prevent degradation or leaks. Also, separation is important, not only by compatibility groups but also by the chemical state (solid, liquid, gas), with highly reactive or toxic chemicals are required to store in a formal safety cabinets. Secondary containment measures, such as spill trays can help to manage spills and improve the efficiency of cleanup. Additionally, training for all personnel involved in chemical handling and storage is essential, like how to read Material Safety Data Sheets (MSDS) or Safety Data Sheets (SDS).