Identification and Analysis of Hazardous Characteristics of Chemicals: Testing Scope, Methods and Ap

Identification and analysis of hazardous characteristics of chemicals is the scientific basis for GHS classification, dangerous goods transport, and chemical safety management worldwide. Accredited third-party laboratories evaluate physical, health, and environmental hazards in accordance with the UN Manual of Tests and Criteria, the GB 30000 series, ISO, and ASTM standards to support safety data sheet (SDS) authoring, labeling, registration, and regulatory compliance. This technical guide explains the scope, sample types, test items, standard methods, and typical applications of chemical hazard identification testing.

Technical Overview

Identification and analysis of hazardous characteristics of chemicals refers to the systematic determination of whether a substance or mixture possesses intrinsic properties that pose physical, health, or environmental risks, using standardized laboratory tests and evaluation procedures. The results provide the technical basis for hazard classification under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), the UN Recommendations on the Transport of Dangerous Goods, and national implementations such as the GB 30000 series of classification standards and GB 6944 for dangerous goods transport.

Hazard identification typically covers three broad categories of dangerous properties, evaluated through a combination of laboratory testing, literature review, and calculation methods:

• Physical hazards, such as explosivity, flammability, oxidizing capacity, self-heating, pyrophoricity, water reactivity, metal corrosion, and pressure hazards of gases.
• Health hazards, including acute toxicity, corrosion and irritation, sensitization, germ cell mutagenicity, carcinogenicity, reproductive toxicity, specific target organ toxicity, and aspiration hazard.
• Environmental hazards, principally acute and chronic aquatic toxicity, degradability, and bioaccumulation potential.

The outcome of hazard identification directly determines classification categories, pictograms, signal words, hazard statements, and precautionary statements on labels and safety data sheets; the assignment of UN numbers, hazard classes, and packing groups for transport; storage and handling requirements; and emergency response measures. It is also a core data requirement for new chemical substance notification, hazardous chemical registration, and import-export compliance in major jurisdictions.

Testing Samples

Pure Substances and Technical-Grade Products

Single-chemical substances, including technical-grade materials containing typical impurities, are tested or evaluated to establish their intrinsic hazard profile. Sample identity and purity are first confirmed by techniques such as gas chromatography, liquid chromatography, infrared spectroscopy, and mass spectrometry, because impurity profiles can materially influence classification conclusions.

Mixtures and Formulations

Multi-component products such as coatings, cleaning agents, polymer preparations, and agrochemical formulations are assessed either by direct testing or by applying recognized calculation methods, cut-off values, and bridging principles based on the hazard data of their ingredients. The choice of strategy depends on composition information availability and the applicable regulatory framework.

Unknown, Unlabeled, or Contaminated Samples

Samples of unknown composition, deteriorated products, or materials from spill and incident investigations undergo preliminary structural identification using spectroscopic and chromatographic screening, followed by targeted hazard testing to support safe handling, storage, and disposal decisions.

Intermediates, By-Products, and Chemical Wastes

Process intermediates, distillation residues, reaction by-products, and waste streams are characterized to determine whether they meet hazard classification criteria, which is essential for process safety reviews, waste management licensing, and transport of waste dangerous goods.

Testing Items

Testing programs are designed endpoint by endpoint according to the classification criteria of the GHS and its national implementations. The most commonly requested test items are listed below.

Physical Hazard Test Items

• Explosive properties and thermal stability screening
• Flammability of gases and determination of flammability limits
• Flash point and fire point of flammable liquids
• Burning rate and flammability of solids
• Pyrophoric properties of liquids and solids
• Self-heating behavior of substances
• Emission of flammable gases in contact with water
• Oxidizing properties of gases, liquids, and solids
• Self-reactive substances and organic peroxides, including self-accelerating decomposition temperature (SADT)
• Corrosion to metals
• Gases under pressure and aerosol flammability

Health Hazard Test Items

• Acute toxicity via the oral, dermal, and inhalation routes
• Skin corrosion and skin irritation
• Serious eye damage and eye irritation
• Skin sensitization and respiratory sensitization evaluation
• Germ cell mutagenicity, including bacterial reverse mutation assays and chromosomal aberration tests
• Carcinogenicity assessment based on available data
• Reproductive and developmental toxicity evaluation
• Specific target organ toxicity after single or repeated exposure
• Aspiration hazard evaluation

Environmental Hazard Test Items

• Acute and chronic toxicity to fish, aquatic invertebrates, and algae
• Ready biodegradability and inherent biodegradability
• Bioaccumulation potential, including octanol-water partition coefficient and bioconcentration assessment
• Hazard to the ozone layer based on available data

Testing Methods

Accredited third-party laboratories perform physical hazard testing in accordance with the UN Manual of Tests and Criteria and the corresponding GB, ISO, and ASTM methods, while health and environmental hazard studies are conducted under good laboratory practice in line with nationally adopted test guidelines harmonized with internationally recognized protocols.

Flammability Testing

Flash point is determined by Pensky-Martens closed cup methods (GB/T 261, ISO 2719, ASTM D93), rapid equilibrium closed cup methods (ISO 3679, ASTM D3278), or Tag closed cup methods (ASTM D56, ISO 13736), depending on viscosity and expected flash range. Fire point is measured by the Cleveland open cup method (ASTM D92, ISO 2592), auto-ignition temperature by GB/T 5332 and ASTM E659, flammability limits of gases by ISO 10156 and GB/T 12474, and burning rate of flammable solids by UN Test N.1.

Reactivity and Oxidizing Testing

Reactivity endpoints follow the UN test scheme: pyrophoric solids and liquids (UN Tests N.2 and N.3), self-heating substances (UN Test N.4), substances emitting flammable gas with water (UN Test N.5), oxidizing solids (UN Tests O.1 and O.3), oxidizing liquids (UN Test O.2), and corrosion to metals (UN Test C.1, supported by immersion methods such as ASTM G31).

Thermal Stability and Explosive Screening

Initial screening is performed by differential scanning calorimetry per ASTM E537 to identify exothermic decomposition and energy release. Where the screening indicates explosive potential, confirmatory assessment follows UN Test Series 1 to 3. Self-reactive substances and organic peroxides are evaluated under UN Test Series E to H, with SADT determined using UN Tests H.1 to H.4.

Health Hazard Testing

Acute toxicity studies follow GB/T 21603 for the oral route, GB/T 21604 for the dermal route, and GB/T 21605 for inhalation, using dose-step or limit-test designs consistent with internationally harmonized guidelines. Skin and eye irritation endpoints are covered by the GB/T 21606 to 21609 series, and sensitization by GB/T 21608, with the local lymph node assay accepted as an alternative where applicable. Genotoxicity screening uses the bacterial reverse mutation test (GB/T 21786), and repeated-dose, reproductive, and developmental endpoints draw on the GB/T 21750 series. In vitro strategies, read-across, and weight-of-evidence approaches are applied wherever scientifically justified to reduce animal use.

Environmental Hazard Testing

Aquatic toxicity is assessed using the algal growth inhibition test (GB/T 21805), the daphnia acute immobilization test (GB/T 21830), and the fish acute toxicity test (GB/T 27861), with chronic endpoints added when long-term classification is required. Ready biodegradability is determined by the methods of GB/T 21801 to 21803, and bioaccumulation potential by bioconcentration studies (GB/T 21828) together with partition coefficient measurement by shake-flask or HPLC-based methods.

Applications

GHS Classification, SDS Authoring, and Labeling

Test results feed directly into classification decisions under the GB 30000 series and the GHS purple book, enabling preparation of compliant safety data sheets in line with GB/T 16483, GB/T 17519, and ISO 11014, and labels with the correct pictograms, signal words, and hazard statements per GB 15258.

Dangerous Goods Transport Compliance

Classification data support the assignment of UN numbers, hazard classes or divisions, and packing groups according to GB 6944, GB 12268, and the UN Model Regulations, and provide the technical documentation required for dangerous goods declaration, packaging selection, and customs clearance.

Hazardous Chemicals Registration and Catalogue Determination

Identification reports are used to judge whether a substance meets the criteria of national hazardous chemicals catalogues, to support hazardous chemical registration, and to compile the hazard data packages required for new chemical substance notification and post-market supervision.

Process Safety, Storage, and Risk Management

Hazard data inform process hazard analyses, storage arrangement and separation requirements under GB 15603, fire protection design, occupational exposure controls, emergency response planning, and the classification of chemical waste for disposal.

FAQ

What deliverables are provided after hazardous characteristics identification?

Typical deliverables include item-by-item test reports with raw data and method references, an integrated hazard identification report, and a classification conclusion listing the applicable hazard classes, categories, and label elements under the GHS and relevant national standards.

Do mixtures always need to be tested?

No. Where reliable data exist for the ingredients, mixtures can often be classified by calculation using concentration cut-off values, or by bridging principles from tested similar formulations. Direct testing is recommended when ingredient data are incomplete or when interactions may change the hazard profile.

Can existing literature data replace laboratory testing?

Yes, when the data are adequate, relevant, and reliable, they may be used under a weight-of-evidence approach. Testing is required when data gaps remain for classification-relevant endpoints or when regulations mandate study-based evidence.

How much sample is required for testing?

Physical hazard tests generally require small quantities, often from tens of grams up to a few hundred grams depending on the endpoint. Health and environmental studies require larger amounts, and the sampling plan is confirmed case by case with the laboratory before testing begins.

How long does the identification process take?

Physical hazard and screening tests are usually completed within one to four weeks. Ecotoxicity studies may take several weeks, and mammalian toxicity endpoints require longer durations, so overall timelines depend on the endpoint matrix defined for each project.

When is hazardous characteristics identification legally required?

It is commonly required for new chemical substance notification, hazardous chemical registration, confirmation against national hazardous chemicals catalogues, dangerous goods transport classification, SDS and label preparation, and support for safety reviews in manufacturing, warehousing, and trade.