Acrylonitrile (2-propenenitrile; CAS 107-13-1; EC 203-466-5) is a phase-in substance under Article 3(20) of Regulation (EC) No 1907/2006 and is fully registered under REACH. The harmonised classification in Annex VI of Regulation (EC) No 1272/2008 lists Flam. Liq. 2 H225; Acute Tox. 3 H301, H311, H331; Skin Irrit. 2 H315; Eye Dam. 1 H318; Skin Sens. 1 H317; Carc. 1B H350; STOT RE 1 H372; Aquatic Acute 1 H400; and Aquatic Chronic 2 H411. For acrylonitrile, REACH status comprises registration, import control, and downstream duties. The registration dossier covers manufacture and import volumes above 1 000 t/a; the chemical safety report is required because the substance is classified carcinogenic and specific-target-organ toxicant. The lead registrant submits a joint dossier in IUCLID containing Annex VII–X endpoint data, chemical safety assessment, and exposure scenarios for polymer-grade monomer use. Downstream users receive registration status through the extended safety data sheet, which carries exposure scenarios for monomer transfer, polymerisation, and maintenance.

What import control obligations arise from REACH Title II for acrylonitrile consignments?

A non-EU supplier cannot register directly. Article 8 of Regulation (EC) No 1907/2006 permits the appointment of an only representative established in the EU. An importer must verify that the annual tonnage is covered by a valid registration or that an only representative has included the importer’s volume in the joint submission. Customs enforcement of acrylonitrile entries uses the ECHA registration number quoted on the safety data sheet under Article 31(1)(a). Because the substance carries harmonised Carc. 1B classification, Annex XVII entries 28 to 30 restrict supply to the general public in specific product categories. Import control therefore combines REACH registration, CLP notification under Article 40, and Annex XVII restriction screening. Bulk acrylonitrile consignments are normally shipped with monomethyl ether of hydroquinone inhibitor at 35–50 ppm and require SDS documentation of inhibitor concentration and maximum storage temperature. Border enforcement findings frequently concern missing exposure-scenario annexes or incorrect registration numbers on customs documentation.

Acrylonitrile boils at 77.3 °C at 101.3 kPa; the closed-cup flash point is -1 °C. Vapour pressure at 20 °C is 11.5 kPa, and the lower and upper explosion limits are 2.8 vol% and 28 vol%. Vapour is heavier than air and can travel to distant ignition sources. Polymer-grade storage is stabilised with monomethyl ether of hydroquinone inhibitor at 35–50 ppm; exposure to heat, light, or free-radical initiators can trigger exothermic polymerisation. Storage tanks are equipped with emergency relief and are connected to thermal oxidisers or carbon adsorption. Transfer lines are earthed and bonded to prevent static discharge. Operators use direct-reading photoionisation detectors calibrated with acrylonitrile response factors when verifying leak tightness; published data for site-specific vapour losses during tanker offloading are limited.

Downstream duty thresholds and exposure scenario conditions

Under Title V of Regulation (EC) No 1907/2006, a downstream user shall not use acrylonitrile outside the conditions described in the annexed exposure scenarios. The exposure scenario for industrial polymerisation includes contributing activities such as tanker unloading, reactor charging, sampling, filtration, and maintenance. Each contributing activity lists operational conditions and risk management measures. Common risk management measures include local exhaust ventilation at reactor charging points, closed-loop transfer, and restricted access during maintenance. The downstream user must compare measured 8-hour time-weighted average inhalation exposure with the DNEL and applicable national occupational exposure limit; if the risk characterisation ratio exceeds 1, additional controls are required. Environmental release scenarios include ERC 6c for monomer use in polymer production and specify on-site waste water treatment before discharge. The downstream user must document that the actual use descriptors match the exposure scenario; deviations in tonnage, process temperature, or ventilation design may invalidate coverage.

Industrial production of acrylonitrile is dominated by propylene ammoxidation in fluidised-bed reactors at 400–450 °C and 0.5–2 bar over bismuth molybdenum oxide catalysts. Molar feed ratios of propylene to ammonia to oxygen are controlled near 1:1.1:1.5, with single-pass conversion above 95% and acrylonitrile selectivity around 80%. Byproducts acetonitrile and hydrogen cyanide are recovered in dedicated columns; hydrogen cyanide requires cyanide-specific containment and caustic scrubbing. Downstream polymer operations convert acrylonitrile into ABS, SAN, nitrile rubber, acrylamide, and acrylic fibre. ABS and SAN processes use emulsion or bulk free-radical polymerisation with acrylonitrile content of 15–35 wt% to raise chemical resistance and heat deflection. Nitrile rubber is produced by cold emulsion polymerisation at 5–15 °C; acrylonitrile content of 18–50 wt% influences oil resistance and low-temperature flexibility. Physical property testing follows ISO 306 for Vicat softening temperature and ISO 179-1 for Charpy impact. Published data for plant-specific acrylonitrile losses to waste water are limited; site monitoring data are required rather than generic emission factors.

If a downstream use falls outside the registered exposure scenario, Article 37(4) applies

Where a downstream user identifies a use not covered by the registration dossier, the downstream user shall either request inclusion by the supplier or prepare a downstream user chemical safety report under Article 37(4). The duty does not apply where the total quantity is below 1 t/a or where the use is product and process oriented research and development under Article 3(23). For a non-covered industrial use above 1 t/a, exposure estimation must follow ECHA guidance R.14, and the downstream user chemical safety report is notified to ECHA. The downstream user must maintain records for 10 years after the last supply of acrylonitrile. In polymer compounding and synthetic rubber plants, enforcement actions commonly identify missing downstream user chemical safety reports where process temperatures or local exhaust ventilation differ from the supplier’s exposure scenario. A use is not considered covered simply because the application name appears in the safety data sheet; the operational conditions and risk management measures must match the actual workplace.

Airborne acrylonitrile is sampled on solid sorbent tubes and analysed by gas chromatography with flame ionisation detection using NIOSH Method 1604 or OSHA Method 37. Sampling flow rates are maintained at 0.01–0.05 L/min for full-shift samples. Direct-read photoionisation detectors are used for leak screening but are not accepted for compliance without laboratory confirmation. Control of worker exposure to acrylonitrile vapour requires closed transfer and local exhaust ventilation. Where measured 8-hour time-weighted average concentrations approach the applicable national occupational exposure limit, air-purifying respirators with type A organic vapour cartridges conforming to EN 14387 are specified. Chemical protective gloves must meet EN ISO 374-1 permeation resistance; barrier materials generally include butyl rubber or fluorinated elastomer with breakthrough time greater than 480 minutes. Eye and face protection follows EN 166. Personal protective equipment selection is not a substitute for engineered vapour recovery; bulk storage tank vents are routed to thermal oxidiser or carbon adsorption with destruction efficiency above 99.9%.

Verification of downstream duty compliance requires a written comparison between the exposure scenario and the actual workplace. The comparison records process temperature, pressure, duration, local exhaust ventilation type, and respiratory protection. For reactor cleaning, supplied-air respirators are used because type A cartridges do not protect against oxygen deficiency and have finite service life. Confined-space entry follows local permit systems; gas detection includes lower explosive limit and toxic mode sensors calibrated for acrylonitrile.

The registration dossier includes chemical safety assessment and Annex XVII restriction checks

Registration under REACH requires a chemical safety report for acrylonitrile because it is classified Carc. 1B and STOT RE 1. The chemical safety report contains exposure scenarios for manufacture, distribution, formulation, industrial use, and any relevant consumer uses. Each exposure scenario is built from use descriptor lists: sector of use, chemical product category, process category, environmental release category, and article category. The risk characterisation ratio must remain below 1 for each exposure route. Environmental assessment uses predicted no-effect concentration values for freshwater, marine water, sediment, and soil, with a default local dilution factor of 10 for surface water. The dossier also checks Annex XVII entries 28 to 30 for CMR supply restrictions. Downstream users are not required to repeat the full chemical safety assessment if the use is covered by the supplier’s exposure scenario; they must retain documentation demonstrating that conditions of use align with the registered scenarios.

Under CLP, a mixture containing acrylonitrile at or above 0.1% is classified as Carc. 1B unless the harmonised entry contains a specific concentration limit. For acute toxicity via inhalation vapour, the generic concentration limit is 0.2%. Formulators must evaluate all hazard classes before placing acrylonitrile-containing mixtures on the market. Article 34 of REACH requires downstream users to communicate new hazard information to suppliers. Article 36 requires retention of safety data sheets and compliance records for 10 years. Distributors must pass the extended safety data sheet and exposure scenarios to downstream users. The registration number communicated under Article 31(1)(a) is the main link between customs documentation, safety data sheets, and ECHA enforcement.