Checklist For Classifying Chemical Substances Safely

Accurate chemical classification is the foundation of safe and compliant international trade. Every shipment depends on correctly identifying hazard properties, assigning the right Globally Harmonized System (GHS) categories, and translating those into the proper Harmonized System (HS) code for customs. A single error in purity thresholds, mixture rules, or regulatory list checks can trigger shipment holds, penalties, or unsafe handling downstream. This article walks through a practical Checklist for Classifying Chemical Substances Safely, covering how to read GHS hazard classes, apply General Interpretative Rules for mixtures, use Safety Data Sheet sections as classification evidence, verify CAS numbers against regulatory inventories, and screen for restrictions under REACH, TSCA, and the Stockholm Convention. You will learn the exact workflow professionals use to align hazard classification, transport documentation, and customs codes so that nothing falls through the cracks.

Understanding the Basics of Chemical Classification

Chemical classification rests on identifying intrinsic hazard properties and assigning standardized categories that trigger specific labeling, packaging, and documentation requirements. The Globally Harmonized System (GHS) provides the universal framework by defining hazard classes for physical, health, and environmental endpoints. Regulatory frameworks such as EU CLP, US OSHA HazCom, and Canada WHMIS adopt GHS building blocks while adding jurisdiction-specific rules. Accurate classification determines the Safety Data Sheet (SDS) content, transport labels, and customs declarations. Misclassification can lead to shipment holds, fines, or unsafe handling. EU chemical imports fell 1% to €322 billion in 2024 according to Eurostat.

Hazard classes defined by GHS and UN Model Regulations

Hazard classes defined by GHS and UN Model Regulations group chemicals by the nature of the danger they present such as flammability, acute toxicity, or aquatic toxicity. Each class contains categories ranked by severity using test data or bridging principles. The UN Model Regulations translate these classes into transport hazard classes and packing groups for safe shipment. A substance may meet criteria for multiple classes requiring all applicable labels and statements. Classification follows a tiered approach: test data on the mixture first, then bridging principles, then ingredient additivity formulas. Always document the classification rationale and data sources for audit readiness.

Role of physical, health, and environmental hazards in classification

Physical hazards such as explosives, flammable gases, and oxidizers dictate packaging groups and segregation rules during transport. Health hazards including carcinogenicity, sensitization, and specific target organ toxicity drive workplace exposure limits and consumer label warnings. Environmental hazards focus on acute and chronic aquatic toxicity and determine marine pollutant status. Each hazard type uses distinct classification criteria and cut-off values. A single substance often carries multiple hazard statements across all three domains. The classification outcome directly shapes the SDS sections 2, 9, 14, and 15. Regulatory lists like REACH Annex XVII or TSCA Section 6 may impose additional restrictions based on these hazard profiles.

Link between classification and required safety documentation

Classification outputs feed directly into the Safety Data Sheet which must follow the 16-section GHS format. Section 2 summarizes hazards, Section 9 lists physical chemical properties, Section 14 provides transport classification, and Section 15 captures regulatory information. Labels must display pictograms, signal words, hazard statements, and precautionary statements derived from the assigned classes. Transport documents require UN numbers, proper shipping names, hazard classes, and packing groups consistent with the SDS. Inconsistent data between the SDS, label, and transport paperwork is a leading cause of customs delays and port detentions. Maintain a classification master file with source data, calculation worksheets, and version history.

How to Determine the Correct HS Code for a Chemical

Finding the correct Harmonized System (HS) code starts with the chemical identity, composition, and physical form of the product. The HS structure uses chemical nomenclature at the 4-digit heading level and further splits by purity, isomer, or derivative at the 6-digit subheading level. National tariff schedules extend to 8 or 10 digits for duty rates and statistical tracking. The HS is the basis for customs tariffs and trade statistics in 211 economies, 158 of which are Contracting Parties to the HS Convention according to the World Customs Organization. An incorrect code risks overpayment of duties, penalties, or seizure. Always verify against the importing country's tariff schedule and explanatory notes.

Identify the chemical's active ingredient and concentration

Identify the chemical's active ingredient and concentration by reviewing the certificate of analysis or product specification sheet. For pure substances the CAS number and systematic name point directly to the appropriate heading. For mixtures the component present in the highest concentration typically determines the heading unless a specific mixture provision applies. Concentration thresholds matter: a 99% pure material may classify under a different subheading than a 90% technical grade. Isomers and stereoisomers often have separate codes. Document the exact composition including impurities above 0.1% as they can shift the classification. Confirm the physical state at import conditions since some codes distinguish solid from liquid forms.

Check for mixtures vs. pure substances under HS rules

Check for mixtures vs. pure substances under HS rules using General Interpretative Rules (GIR) 1 through 3. GIR 1 requires classification by the terms of the headings and any relative section or chapter notes. GIR 3(a) favors the most specific description over a general one. GIR 3(b) directs that mixtures be classified by the material giving them their essential character. GIR 3(c) applies when essential character cannot be determined: the good falls under the heading occurring last in numerical order. Chapter notes in Sections VI and VII (Chapters 28-38) contain detailed chemical classification rules. Many chapters exclude specific mixtures or define purity thresholds. Always read the section and chapter notes before selecting a code.

Consult national tariff schedules and explanatory notes

Consult national tariff schedules and explanatory notes for the final 8 to 10 digit code used at import. The WCO Explanatory Notes provide the official interpretation of each heading and subheading with examples of included and excluded goods. National customs rulings and advance ruling databases show how similar products were classified. The US HTS, EU TARIC, and China Customs tariff are searchable online. Binding rulings offer legal certainty for up to several years. Cross-reference the code with any free trade agreement rules of origin to confirm preferential duty eligibility. Keep records of the classification research including ruling numbers and dates for compliance audits.

Using Safety Data Sheets (SDS) for Classification Support

Section 2: Hazard identification and GHS label elements

Section 2 of the SDS provides the hazard classification of the substance according to GHS criteria, including signal words, hazard statements, and pictograms. This information is essential for determining the correct HS code under Chapters 28-38, where hazard properties often influence classification. For example, a substance classified as toxic or flammable may fall under a different heading than its non-hazardous counterpart. Buyers should compare this section with the supplier’s declared classification to ensure consistency. The United States was the leading destination for EU chemical exports in 2024, at €170 billion, according to Eurostat (via Chemindigest), highlighting the importance of accurate hazard classification for major trade flows. Any discrepancy between Section 2 and the commercial invoice may trigger customs delays or penalties.

Section 3: Composition and impurity profile

Section 3 discloses the chemical identity and concentration of all components, including impurities and additives, which is vital for assessing whether a substance meets purity thresholds defined in chapter notes of the HS tariff. Many chapters in Sections VI and VII (Chapters 28-38) set specific purity limits, for instance, Chapter 29 may exclude certain isomers below 95% purity. If impurities exceed these thresholds, the mixture may need to be classified under a different heading based on the principle of essential character (GIR 3). This section also helps verify if the substance is a single chemical or a blend, directly impacting HS code selection. Always cross-check the CAS number and concentration ranges here with the commercial description to avoid misdeclaration.

Section 14: Transport information and UN number

Section 14 provides transport-related data such as the UN number, proper shipping name, hazard class, and packing group, which align with the substance’s hazard classification and support HS code determination under Chapters 28-38. The UN number, in particular, is a globally recognized identifier that can be cross-referenced with regulatory lists to confirm the substance’s identity and regulatory status. While the HS code focuses on trade taxation, transport information ensures consistency across supply chain documentation. Discrepancies between Section 14 and the SDS’s Section 2 (hazard identification) may indicate outdated or inaccurate data, requiring clarification from the supplier before finalizing the classification decision for customs submission.

Verifying CAS Numbers and Chemical Identifiers

CAS numbers prevent misidentification of isomers and analogs

CAS numbers are unique numeric identifiers assigned to every chemical substance, ensuring precise identification across languages, naming conventions, and regulatory systems. This is critical when distinguishing between isomers, analogs, or substances with similar names but different properties, for example, differentiating between ortho-, meta-, and para-isomers of a compound, which may have distinct hazard profiles and HS code treatments. Relying solely on chemical names can lead to errors due to synonyms or trade names, whereas a CAS number provides an unambiguous reference. Buyers should always require the CAS number on the SDS and commercial invoice and verify it against the substance’s actual composition to prevent misclassification and customs delays.

Cross-referencing CAS with EINECS, REACH, or TSCA listings

Once a CAS number is confirmed, it can be cross-referenced with regional inventories such as EINECS (Europe), REACH registration status, or TSCA (United States) to validate regulatory compliance and classification accuracy. These databases often include additional information on hazards, usage restrictions, or impurity limits that directly affect HS code determination under Chapter Notes. For instance, a substance listed under REACH with a specific restriction may require a different treatment under GIR 3(b) if intended for a particular use. This cross-check ensures that the classification aligns not only with tariff rules but also with applicable safety and environmental regulations, reducing the risk of non-compliance during import clearance.

Using CAS to search official chemical databases

The CAS number enables direct searches in authoritative databases like the CAS REGISTRY, PubChem, or ChemSpider to retrieve verified information on molecular structure, synonyms, and physical-chemical properties. This step is essential when the supplier’s documentation is incomplete or when classifying novel or less common substances. The CAS REGISTRY contains over 290 million unique substances, according to CAS (American Chemical Society), making it the most comprehensive source for chemical identification. By using the CAS number to pull data from these sources, buyers can independently confirm the substance’s identity and ensure that the HS code selected reflects its true chemical nature, supporting accurate and defensible classification decisions.

Checking for Mixtures and Classification Thresholds

How do I classify a chemical mixture versus a pure substance? This section covers the rules for classifying mixtures under GHS, including cutoff concentration limits for hazardous components and when to apply bridging principles.

Apply cutoff values for health hazards

These thresholds are not arbitrary; they reflect the concentration at which a hazard becomes significant enough to trigger labeling and SDS requirements. Buyers should request concentration data from suppliers for all hazardous components, especially when the SDS only provides ranges. If a component falls just below a cutoff, document the reasoning, as regulators may scrutinize borderline cases during audits. Always use the most recent GHS revision adopted by the importing country, as cutoff values can vary slightly between regions.

Use additivity formulas where applicable

For certain hazard classes like skin corrosion/irritation or specific target organ toxicity, GHS permits additivity formulas when test data on the mixture is unavailable. For example, the formula for skin corrosion sums the concentrations of all corrosive components weighted by their potency. If the total exceeds the threshold, the mixture inherits the hazard classification. This approach prevents under-classification when multiple low-concentration irritants act synergistically. However, additivity does not apply to all endpoints, such as sensitization or carcinogenicity, where cutoff rules are stricter. Buyers should verify which formulas apply using the latest GHS guidance documents from the UN or their national authority.

Consider bridging principles when test data is lacking

When a mixture lacks test data, bridging principles allow classification based on similar tested mixtures or the properties of its components. For instance, if a new mixture is diluted with a non-hazardous solvent, and the original concentrated form was tested, the diluted version may be bridged to the same hazard class if the dilution does not reduce the hazard below cutoff limits. Similarly, if a component is substituted with a structurally similar analog, and data exists for the analog, bridging may be justified. These principles rely on scientific justification and must be documented thoroughly. Misapplying bridging, such as assuming similarity without structural or functional basis, can lead to under-classification and compliance risks during customs inspection.

Reviewing Regulatory Lists and Restricted Substances

What regulatory lists should I check to ensure my chemical is not restricted or banned? This section outlines key international and national regulatory inventories (such as REACH, TSCA, or PIC) that buyers must consult to confirm legal status and avoid compliance risks.

Check REACH Candidate List and Annex XIV for SVHCs

Buyers importing into the EU must verify whether a substance appears on the REACH Candidate List of Substances of Very High Concern (SVHCs) or is listed in Annex XIV for authorization. Inclusion in the Candidate List triggers supplier communication duties under Article 33 of REACH, requiring disclosure if the substance is present above 0.1% w/w. Annex XIV substances cannot be placed on the market after their sunset date without authorization. By the 2018 REACH registration deadline, 5,435 companies had submitted 33,363 registration dossiers to ECHA, according to Assent. This high volume underscores the importance of checking both lists, as even substances with registrations may face use restrictions. Always confirm the latest update, as the Candidate List is revised twice yearly.

Verify TSCA Inventory status for US imports

For shipments to the United States, the TSCA Inventory is the primary determinant of whether a chemical may be legally manufactured or imported. Substances not listed on the Inventory are considered new chemicals and require a Pre-Manufacture Notice (PMN) to the EPA, unless exempted. Buyers should request a TSCA compliance statement from suppliers and cross-check the CAS number against the Inventory via the EPA’s Substance Registry Services. Note that some substances may be listed but subject to specific use restrictions or monitoring rules under TSCA Section 5 or 6. Failure to verify TSCA status can result in shipment holds at U.S. customs, civil penalties, or mandatory re-export.

Review PIC Convention and Stockholm POPs list

The Rotterdam Convention (PIC) and Stockholm Convention on Persistent Organic Pollutants (POPs) impose international trade restrictions on hazardous chemicals and persistent pollutants. Chemicals listed under PIC require prior informed consent before export, while those under the Stockholm Convention are subject to global elimination or restriction. Buyers should consult the official PIC website for the list of chemicals in Annex III and the Stockholm Convention site for the current POPs roster. Even if a chemical is not banned, inclusion in these lists often triggers additional documentation requirements, such as export notifications or usage declarations. Ignoring these obligations can lead to shipment rejection at port or inclusion in international watchlists, affecting future trade privileges.

Assessing Purity and Impurity Profiles

Chemical purity directly determines both hazard classification and the applicable HS code because impurities can introduce physical or health hazards that the pure substance does not possess. Under the Globally Harmonized System (GHS) a mixture is classified based on the hazards of its components when they exceed specific concentration limits known as cutoff values. Customs authorities also use purity to distinguish between pure substances and mixtures which fall under different tariff headings and attract different duty rates. Buyers must therefore treat the purity specification as a classification input not just a quality metric.

Impurities may trigger classification even at low levels

Impurities may trigger classification even at low levels because GHS cutoff values for severe hazards such as carcinogenicity mutagenicity or reproductive toxicity can be as low as 0.1 percent. A technical grade solvent containing 0.15 percent benzene by weight must be classified as a Category 1A carcinogen even though the main component is benign. This reclassification changes the required label elements the Safety Data Sheet content and the transport proper shipping name. Buyers should request the specific impurity profile for each batch rather than relying on a generic product specification sheet.

Request full impurity breakdown in COA or SDS

Request full impurity breakdown in the Certificate of Analysis or Safety Data Sheet because Section 3 of the SDS only requires disclosure of ingredients that exceed the GHS cutoff values or have occupational exposure limits. Suppliers often omit impurities below those thresholds even though they may be relevant for customs valuation or import licensing. A formal request for the complete chromatographic profile including peaks below the reporting limit ensures the buyer can perform an independent classification check. This is especially critical for pharmaceutical intermediates and electronic grade chemicals where trace metals or residual solvents affect both regulatory status and end use suitability.

Compare against GHS cutoff values for hazardous impurities

Compare against GHS cutoff values for hazardous impurities by building a reference table of the concentration limits in the current GHS revision for each hazard class. For example the cutoff for Skin Sensitization Category 1 is 0.1 percent while Acute Toxicity Category 4 uses a concentration limit defined in GHS guidelines. If the impurity profile shows a skin sensitizer at 0.12 percent the mixture must carry the GHS07 exclamation mark pictogram and the H317 hazard statement. Document this comparison in the classification worksheet so auditors can trace the decision from raw data to final hazard class and HS code.

Documenting Classification Decisions

Documenting classification decisions creates an audit trail that demonstrates due diligence when customs or regulatory authorities challenge a declaration. A complete file links the raw compositional data the regulatory lists consulted and the reasoning that led to the chosen HS code and hazard class. This practice is essential as trade volumes grow; EU exports of chemicals and related products to non-EU countries reached a record €560 billion in 2024 according to Eurostat (via Chemindigest). With higher volumes comes increased scrutiny so a structured documentation system reduces the risk of penalties shipment delays or loss of trusted trader status.

Maintain a classification worksheet with assumptions

Maintain a classification worksheet with assumptions that records the substance identity the CAS number the purity specification the impurity profile the GHS version used and the regulatory lists checked. Include the specific cutoff values applied the hazard classes triggered and the resulting UN proper shipping name packing group and HS code. Note any expert judgment used such as bridging principles for mixtures without test data. Store this worksheet in a version controlled folder so that any future reclassification can reference the exact logic applied at the time of shipment.

Archive SDS versions used for each shipment

Archive SDS versions used for each shipment because suppliers update SDS documents periodically and the version in force at the time of export governs the classification. Save the PDF with a filename that includes the product code the supplier name the SDS revision date and the shipment date. Link each archived SDS to the corresponding classification worksheet entry. This prevents disputes where a later SDS revision removes a hazard statement that was present when the goods were shipped and customs requests proof of the original classification basis.

Keep emails or forms confirming supplier declarations

Keep emails or forms confirming supplier declarations especially when the supplier provides a written statement that a substance is not subject to REACH authorization PIC notification or TSCA Section 5 restrictions. These communications serve as contemporaneous evidence that the buyer relied on the supplier expertise in good faith. Attach them to the shipment file alongside the commercial invoice packing list and bill of lading. In the event of a customs audit the complete package shows a systematic approach rather than an ad hoc guess. For more on avoiding common pitfalls see our guide on common mistakes in HS code classification for exports.

Validating Supplier-Provided Classification Data

Compare supplier SDS with ECHA or PubChem entries

Start by checking the CAS number on the supplier’s SDS against the substance entry in ECHA’s C&L Inventory or PubChem. These databases list harmonized classifications under CLP and GHS criteria. If the supplier’s SDS shows a hazard class not present in these sources, request clarification. For example, if the supplier flags a substance as carcinogenic but ECHA lists only skin irritation, ask for the study data supporting the higher hazard. Discrepancies may stem from impurities, different purity grades, or outdated SDS versions. Always use the CAS number as the primary identifier since chemical names can vary across languages and suppliers. Save a screenshot or PDF of the database entry with the date accessed for your records.

Use HS prediction tools with CAS and formula inputs

Input the CAS number and molecular formula into an HS code prediction tool that references the Harmonized System nomenclature. Tools like those from customs authorities or trade data platforms can suggest likely HS headings based on chemical function or use. Cross-check the predicted HS code with the supplier’s declaration. If the supplier uses a code for a finished product but your substance is an intermediate, the prediction may differ. Note that HS classification depends on use as well as composition so a pure chemical might fall under different headings if sold as a pesticide versus a pharmaceutical intermediate. Use the tool as a starting point not a final authority.

Consider spot testing for high-risk or novel substances

For substances with limited public data or those involved in high-value shipments consider arranging independent laboratory testing. A basic purity check via HPLC or GC can confirm if the substance matches the supplier’s assay. If the SDS claims the substance is non-hazardous but testing reveals a hazardous impurity above threshold levels you may need to reclassify the mixture. Testing is especially relevant for novel compounds not yet listed in ECHA or PubChem. Choose an accredited lab and request a certificate of analysis that includes the test method CAS number and results. Attach this report to your classification worksheet as supporting evidence.

Understanding Transport and Packaging Implications

Determine UN number and packing group from Section 14 of SDS

Section 14 of the SDS contains the UN number proper shipping name hazard class and packing group. The packing group I II or III indicates the degree of danger with I being highest. This information directly determines the type of packaging required for transport. For example a substance with UN 1993 and packing group II requires intermediate packaging performance. Always verify that the UN number matches the hazard class in Section 2. If Section 14 is blank or says “not applicable” for a substance you believe is hazardous check Sections 2 and 9 for clues about flammability toxicity or corrosivity that might trigger transport regulations.

Apply correct label elements (pictograms signal words)

Using the hazard class and category from Section 2 of the SDS select the corresponding GHS pictograms signal word and hazard statements. For example a substance classified as flammable liquid category 2 needs the flame pictogram the signal word “Danger” and hazard statement H225. These elements must appear on the outer packaging in the correct size and format as dictated by the IMDG ADR or IATA regulations. Label durability matters too use labels that withstand 30 days of seawater exposure for sea freight. Incomplete or incorrect labeling is a common cause of shipment delays at customs or refusal by carriers.

Select packaging based on PG I II or III performance standards

Packing group determines the minimum performance standard for packaging. PG I requires high performance packaging II medium and III low. Refer to the relevant regulation IMDG ADR or IATA for specific packaging codes. For instance a PG I liquid might need a combination packaging with inner glass bottles and outer steel drum while PG III might allow a single polyethylene jerrycan. Always check that the packaging bears the UN certification mark indicating it passed the required tests. Reusing packaging is only allowed if it remains intact and suitable for the hazard class and packing group of the new substance.

Conclusion

Accurate chemical classification requires a disciplined workflow that aligns GHS hazard categories with HS code selection through verified SDS data, CAS numbers, and regulatory list screening. Apply General Interpretative Rules systematically, document the rationale for mixture versus pure substance decisions, and cross-reference Section 2, Section 3, and Section 14 of the SDS to prevent discrepancies that cause customs delays. Confirm purity thresholds against chapter notes and screen every component against REACH, TSCA, and Stockholm Convention restrictions before finalizing the tariff code.

Maintain a classification master file with source data, calculation worksheets, and version history to support audit readiness and binding ruling applications. Treat classification as a living process that updates when formulations change or regulatory lists expand. Start your next classification review at https://globaltradeplaza.com/blog for current regulatory updates and practical templates.

Frequently Asked Questions

What is the difference between HS code and CAS number?

An HS code is a customs tariff classification used for trade statistics and duty assessment, while a CAS number is a unique chemical identifier for substance recognition. The HS code depends on composition, purity, and physical form for taxation purposes, whereas the CAS number remains fixed for a specific molecular structure regardless of mixture or form.

Can I use the same HS code for a chemical in all countries?

The first six digits of the HS code are harmonized globally under the WCO system, but countries may add two to four more digits for national tariff distinctions. Always verify the full 8- or 10-digit code in the importing country’s tariff schedule, as subdivisions can differ based on local regulations or product specifics.

How often does the HS nomenclature for chemicals change?

The HS nomenclature is updated every five years by the World Customs Organization, with the most recent version effective from 2022. Interim updates may occur through explanatory notes or national rulings, but major structural changes follow the five-year cycle to maintain stability in global trade classification.

Who is responsible for declaring the correct HS code at customs?

The importer of record is legally responsible for declaring the correct HS code at customs, regardless of supplier-provided information. Customs authorities hold the importer accountable for accuracy, and errors can lead to delays, penalties, or seizure, making due diligence essential even when relying on supplier documentation.

Is an SDS required for every chemical import?

An SDS is required for every chemical import if the substance is hazardous under GHS criteria or if the importing country’s regulations mandate it for safety communication. Non-hazardous substances may not require an SDS, but many importers request one voluntarily for handling clarity and compliance with workplace safety rules.

How do I classify a chemical mixture under GHS rules?

Classify a chemical mixture under GHS by first testing the mixture as a whole, then applying bridging principles if test data is unavailable, and finally using ingredient additivity formulas. Cutoff concentrations apply, for example, 0.1% for carcinogens and 1% for acute toxicity Category 4, to determine if a hazard classification is triggered.

What does Section 14 of an SDS tell me about transport?

Section 14 of an SDS provides the UN number, proper shipping name, hazard class, and packing group for transport compliance. This information ensures alignment with international regulations like the UN Model Regulations and supports accurate completion of shipping documents such as the dangerous goods declaration.

Where can I find the official list of hazardous chemicals?

Official lists of hazardous chemicals are maintained by regulatory bodies such as ECHA for REACH in the EU, OSHA for HazCom in the US, and WHMIS in Canada. These lists include substances subject to classification, labeling, and SDS requirements under respective GHS-adopted frameworks and are updated regularly based on scientific review.

What happens if I use the wrong HS code for a chemical?

Using the wrong HS code can result in overpayment or underpayment of duties, customs delays, shipment holds, or penalties for incorrect declaration. Authorities may issue fines or seize goods if the error is deemed intentional or negligent, and recovery of overpaid duties often requires a formal post-correction request.

Can impurities affect the HS code of a substance?

Yes, impurities can affect the HS code if they exceed purity thresholds defined in chapter notes of the HS tariff, particularly in Chapters 28-38. For example, a substance below 95% purity may be classified differently than its pure form, as impurities can alter the essential character under GIR 3(b) or trigger mixture classification rules.

How do I verify a supplier’s classification claims?

Verify a supplier’s classification claims by cross-checking the CAS number in Section 3 of the SDS against authoritative databases like PubChem or the CAS REGISTRY, then reviewing Sections 2 and 14 for hazard and transport consistency. Request supporting documentation such as test reports or third-party certificates of analysis to validate the claims.

Where do I check if a chemical is restricted under REACH?

Check if a chemical is restricted under REACH by consulting Annex XVII of the REACH regulation on the ECHA website, which lists substances with usage limitations or bans. You can search by CAS number, EC number, or substance name to find specific restrictions, including concentration limits and affected applications.