PRODUCTS

PARAFORMALDEHYDE 97%

Paraformaldehyde (PFA) is the smallest polyoxymethylene, the polymerization product of formaldehyde with a typical degree of polymerization of 8–100 units. Paraformaldehyde 97% commonly has a slight odor of formaldehyde due to decomposition. Paraformaldehyde 97% is a poly-acetal. Paraformaldehyde 97% can be depolymerized to formaldehyde gas by dry heating and to formaldehyde solution by water in the presence of a base, an acid or heat. The high purity formaldehyde solutions obtained in this way are used as a fixative for microscopy and histology.

CAS No. : 30525-89-4

Synonyms:
Polyoxymethylene; PFA; 97%; formaldehyde; formalin; methanal; formol; 50-00-0; Paraformaldehyde; Methylene oxide; Oxomethane; Paraform; Formic aldehyde; Oxymethylene; Methyl aldehyde; paraformaldehit %97; paraformaldeyit %97; Fannoform; Formalith; Formaldehyde solution; Methaldehyde; Oxomethylene; Superlysoform; Formalina; Lysoform; Morbicid; Karsan; Formaldehyd; Formaline; Polyoxymethylene; Aldehyde formique; FYDE; Formaldehyde, gas; Formalin 40; Aldeide formica; 30525-89-4; Oplossingen; Dormol; Polyformaldehyde; Formalin-loesungen; Paraformic aldehyde; Rcra waste number U122; oxomethyl; Aldacide; Aldehyd mravenci; Paraformaldehydum; Oilstop, Halowax; Flo-Mor; CH2O; UN 2209 (formalin); Formaldehyde (gas); Formaldehyde polymer; Formaline [German]; NCI-C02799; Formalina [Italian]; Oplossingen [Dutch]; HCHO; Polyoxymethylene glycol; Polymerised formaldehyde; Fordor; UN 1198; Aldehyd mravenci [Czech]; POLY(OXYMETHYLENE); Aldeide formica [Italian]; Aldehyde formique [French]; Formalin-loesungen [German]; Formaldehyd [Czech, Polish]; Aldehyde formique [ISO-French]; BFV; Formaldehyde, solution; Paraformaldehyde, polymer; Formalin Solution; Formaldehyde, Para; Formaldehyde (USP); Formaldehyde, solution (37% to 50%); Formalde-Fresh Solution; Formalin, Buffered, 10%; Formaldehyde, 37% by Weight; Formaldehyde, 40% by Volume; Paraformaldehyde, 90%, pure; PARAFORMALDEHYDE 97%; Formaldehyd (CZECH, POLISH); Formalde-Fresh Solution, Buffered; Formalaz; Formaldehyde, solutions, flammable [UN1198] [Flammable liquid]; Formaldehyde, solutions with not <25% formaldehyde [UN2209] [Corrosive]; Buffer Solution, pH 4.00, Color-Coded Red; Formic aldehyde; Paraformaldehyde [JAN]; formaidehyde; formaldeyde; formaldhyde; methanon; paraformaldehyd; paraformaldehye; Paraformaldehyde [USP:JAN]; Formadehyde; Formaldehye; Veracur; Durine; paraformaidehyde; Formaldehyde, 37 wt% sol. in water, stab. with 5-15% methanol; Formaldehyde, ACS reagent, 37 wt% sol., stab. 10-15% methanol; para formaldehyde; paraform-aldehyde; Para-formaldehyde; Formalin solution, neutral buffered, 10%, histological tissue fixative; F-gen; Hyperband (TN); Formalin [JAN]; EINECS 200-001-8; Methan 21; HCOH; Floguard 1015; Formalin (JP17); CARBON-MONOXIDE; Hercules 37M6-8; H2CO; WLN: VHH; Formaldehyde [BSI:ISO]; Paraformaldehyde (JP17); Melamine-Formaldehyde Resin; Formaldehyde, 4% in PBS; Formaldehyde, methanol-free; Formaldehyde solution, 10%; Formaldehyde, solution, flammable; BufferPac™ Color-Coded Solutions; Formaldehyde, 37% in aqueous solution; Formaldehyde solution 37 wt. % in H2O; formaldehyde;formaldehyde [bsi:iso];methanal;formaldehyde (act. 37%);formalin;formaldehyde formaldehyde [bsi:iso] methanal formaldehyde (act. 37%) formalin; Formaldehyde solution, 37 wt. % in H2O; Formaldehyde, solutions (Formalin) (corrosive); Paraformaldehyde [UN2213] [Flammable solid]; Formaldehyde Solution, 10% w/w in 84.8 - 94.2% H2O; Paraformaldehyde, 16% w/v aqueous solution, methanol free; Formaldehyde neutral buffer solution, 3.7% formaldehyde in H2O

Paraformaldehyde 97%

Synthesis of Paraformaldehyde 97%
Paraformaldehyde 97% forms slowly in aqueous formaldehyde solutions as a white precipitate, especially if stored in the cold. Formalin actually contains very little monomeric formaldehyde; most of it forms short chains of polyformaldehyde. A small amount of methanol is often added as a stabilizer to limit the extent of polymerization.

Reactions of Paraformaldehyde 97%
Paraformaldehyde 97% can be depolymerized to formaldehyde gas by dry heating and to formaldehyde solution by water in the presence of a base, an acid or heat. The high purity formaldehyde solutions obtained in this way are used as a fixative for microscopy and histology.

The resulting formaldehyde gas from dry heating Paraformaldehyde 97% is flammable.

Uses of Paraformaldehyde 97%
Once Paraformaldehyde 97% is depolymerized, the resulting formaldehyde may be used as a fumigant, disinfectant, fungicide, and fixative. Longer chain-length (high molecular weight) polyoxymethylenes are used as a thermoplastic and are known as polyoxymethylene plastic (POM, Delrin). It was used in the past in the discredited Sargenti method of root canal treatment.

Paraformaldehyde 97% is not a fixative; Paraformaldehyde 97% must be depolymerized to formaldehyde in solution. In cell culture, a typical formaldehyde fixing procedure would involve using a 4% formaldehyde solution in phosphate buffered saline (PBS) on ice for 10 minutes. In histology and pathology specimens preparation, usually, the fixation step is performed using 10% Neutral Buffered Formalin (4% formaldehyde) for, at least, 24 hours.

Paraformaldehyde 97% is also used to crosslink proteins to DNA, as used in ChIP (chromatin immunoprecipitation) which is a technique to determine which part of DNA certain proteins are binding to.

Paraformaldehyde 97% can be used as a substitute of aqueous formaldehyde to produce the resinous binding material, which is commonly used together with melamine, phenol or other reactive agents in the manufacturing of particle board, medium density fiberboard and plywood.

Toxicity of Paraformaldehyde 97%
As a formaldehyde releasing agent, Paraformaldehyde 97% is a potential carcinogen. Its acute oral median lethal dose in rats is 592 mg/kg.

Properties of Paraformaldehyde 97%
Chemical formula OH(CH2O)nH (n = 8 - 100)
Appearance white crystalline solid
Density 1.42 g·cm−3 (25 °C)
Melting point 120 °C (248 °F; 393 K)
Solubility in water low

General description of Paraformaldehyde 97%
Paraformaldehyde 97% is also referred as polyoxymethylene. Paraformaldehyde 97% participates as an external CO source in the synthesis of aromatic aldehydes and esters.

Paraformaldehyde is an ideal fixative used in histology. Paraformaldehyde 97% is generally preferred over other fixative as the others result in more silver grains on the tissues. Paraformaldehyde 97%, appropriately combined with DMSO (dimethyl sulfoxide) ensures its uniform distribution over the tissue section. Paraformaldehyde is also used in recognizing and stabilizing the expression of intracellular antigen.

Application of Paraformaldehyde 97%
Paraformaldehyde 97% has been used as a fixative in histological analysis. Paraformaldehyde 97% has also been used in mitotic catastrophe assay.

Paraformaldehyde 97% is the informal name of polyoxymethylene, a polymer of formaldehyde (also known by many other and confusing names, such as ‘paraform’, ‘formagene’, ‘para’, ‘polyoxymethane’). It is slowly formed as a white precipitate by condensation from the predominant species methanediol (formaldehyde hydrate) in solutions of formaldehyde (which may also be called ‘formalin’, ‘formal’, or ‘formalose’) on standing, in an equilibrium (Fig. 3.1). The solution is predominantly of oligomers, but when n becomes large enough the material becomes sufficiently insoluble as to precipitate, when the condensation may still continue. The resulting solid may have n range from ~ 8 to 100, or more. The reaction is driven to the left, to release formaldehyde, by a low concentration of formaldehyde, and accelerated by acidic or alkaline conditions. Solid Paraformaldehyde 97% smells plainly of the monomer (b.p. − 21 °C), so it is essentially a convenient means of delivering formaldehyde slowly.

Paraformaldehyde 97% has documented uses as a disinfectant, fungicide, fixation reagent and in the preparation of formaldehyde. In fluorescence studies, paraformaldehyde 97% has been used as as a formalin fixative to fix cells and tissues. To use the chemical as a fixative, it must be converted to the monomer formaldehyde by heating as formaldehyde is the active chemical in fixation.

Paraformaldehyde 97% is a polymer of formaldehyde. Paraformaldehyde 97% itself is not a fixing agent, and needs to be broken down into its basic building block formaldehyde. This can be done by heating or basic conditions until it becomes solubilized. Once that occurs, essentially they are exactly the same.

Beware though, some commerical formaldehyde solutions contain methanol to prevent polymerization (into Paraformaldehyde 97%), and this methanol can potentially inhibit your experiment.

We allow Paraformaldehyde 97% to heat over-night, filter, and use fresh for our fixation protocols for immunofluorescence, and we have great success. We store the Paraformaldehyde 97% in the fridge, but do not use it after a few days because it will eventually polymerize again and become less efficacious.

A polymer consists of 10 to 100 formaldehyde units. Not only the hazardous effects to human health and environment but also the difficulties in processing and storing of formaldehyde gas leads to paraformaldehyde use in formaldehyde resins. Paraformaldehyde decomposes into the formaldehyde at nearly 150°C.

Paraformaldehyde 97% applications
Applications
The most important use of Paraformaldehyde 97% is as a source of formaldehyde groups in the production of many thermosetting resins, together with phenol, urea, melamine, resorcinol and other similar reagents. These resins are used as moulding powders; in the wood industry as glues for chipboard, plywood and furniture; as bonding resins for brakes, abrasives and foundry dyes; as finishing resins for paper and textiles; as driers and glossing agents for paints; as insulating varnishes for electrical parts.

Some typical formulations for the production of such resins starting from Paraformaldehyde 97% include dichloroethyl formal, methyl phenol, disinfectants, insecticides, pharmaceuticals such as vitamin A, embalming preparations, dyestuff and special plasticizers.

In addition, Paraformaldehyde 97% is used as a fungicide and bactericide in industries as varied as crude oil production, beet sugar refining, and warehousing.

Paraformaldehyde 97% has widespread acceptance as an additive to stop fermentation of the starch on oil-well-drilling muds.

The sugar beet industry used it to minimize the growth of algae in its continuous diffusers. Hotels and motels in humid areas often use it, with or without added mothproofing agents, in small bags hung in closets to prevent the formation of mildew.

Paraformaldehyde 97% possesses the common characteristics with a wide range of applications

Paraformaldehyde 97% is the smallest solid form of liquid formaldehyde, formed by the polymerization of formaldehyde with a typical degree of polymerization of 8-100 units. As Paraformaldehyde 97% is basically a condensed form of formaldehyde, it possesses the common characteristics with a wide range of applications.

Advantages of Paraformaldehyde 97% in resin production
as compared to aqueous formaldehyde
Paraformaldehyde 97% does not need to be dissolved in water in order to take part in a chemical reaction.
Higher productivity from existing equipment and less water to be removed from the resin product.
Paraformaldehyde 97% made with very low acid content in a chemical resistant environment can prevent the formation of acidic by-products.
We offer a prilled form, which is stable and very easy to store. Paraformaldehyde 97% storage is less expensive than the storage of formaldehyde solution, which requires expensive tanks and which may need stabilization or be kept warm.
It eliminates the risk of transporting liquid formalin, which is notoriously dangerous. Perfect for small uses straight from the bag.
Use of Paraformaldehyde 97% is convenient and safe. It avoids pollution arising from the disposal of the distillate obtained in the thermosetting resin production which is contaminated with organic matter.

Typical Properties of Paraformaldehyde 97%
Color White
CAS Number 30525-89-4
Appearance Free Flowing Prilled
Molecular Formula OH-(CH2O)n-H where n=8 to 100 units
Paraformaldehyde 97% Content 92% ± 1% / 96% ± 1%
Water Content 8% ± 1% / 4% ± 1%
Reactivity 2 – 8 min
Mean Particle Size 250 – 350 µm
Ash 0.01 – 0.05%
Bulk Density 650 – 850 kg/m3
Melting Point 120 – 175 C
Ph 4 – 7
Flammability combustible, with flash point (tag open cup) of about 93 C
Vapour Pressure varies with air humidity, being between 23 and 26 mmHg at 25 C

Applications of Paraformaldehyde 97%

Resins Industry
The most important use of Paraformaldehyde 97% is as a source of formaldehyde groups in the production of many thermosetting resins, together with phenol, urea, melamine, resorcinol and other similar reagents. These resins are used as moulding powders; in the wood industry as glues for chipboard, plywood and furniture; as bonding resins for brakes, abrasives and foundry dyes; as finishing resins for paper and textiles; as driers and glossing agents for paints; as insulating varnishes for electrical parts.

Disinfectant
Paraformaldehyde 97% generates formaldehyde gas when it is depolymerized by heating. The depolymerized material reacts with the moisture in the air to form formaldehyde gas. This process is used for the decontamination of large spaced and laminar-flow biological safety cabinets when maintenance work or filter changes require access to the sealed portion of the cabinet. It is used in the poultry industry as a disinfectant in the hatcheries, and cattle and sheep industry for sanitizing the bedding in the sheds. It releases formaldehyde gas when the temperatures increase. It reduces contamination levels caused by moulds, viruses and bacteria.

Agriculture and Pesticides
Most Paraformaldehyde 97% consumed by the agrochemicals industry is for the herbicides such as bismerthiazol, butachlor, acetochlor, glyphosate, and machete.

Embalming Process
Formalin is used during embalming processes as a disinfectant and preservative. It is used as an injection fluid in arterial and cavity embalming, and in surface embalming as a fluid for soaking surface packs or a gel applied to the skin or internal surfaces. Paraformaldehyde 97%, a powdered polymer form of formaldehyde, is also sometimes used in embalming processes.

Reagent for Organic Reactions
In microbiology laboratories, fixation process (immunofluorescence) uses formalin 4% concentration. A blog by researchers mentioned that preparing this solution “fresh” from Paraformaldehyde 97% is better than using formalin that has been kept for some time. It is because more methylene glycol is present compared to its dimer and trimer oligomers and such solution of formalin 4% is absent of methanol.

Oil Well Drilling Chemicals
Paraformaldehyde 97% is used in the manufacturing of 1,3,5-triazine used as H2S scavenger in Oil drilling process.

Paraformaldehyde 97% tablets are very effective against a wide spectrum of organisms. They may be recommended for targeted degerming measures in medical practice. Their utilization requires the observance of the conditions necessary for their efficient use. The tablets should be employed only in containers which are as tight-fitting as possible (preferentially instrument cabinets, Heynemann cabinets, catheter boxes and plastic bags). Paraformaldehyde 97% tablets are well suited for the reduction of the bacterial population and the storage of nonwrapped sterilized instruments. For this purpose, 1 tablet/dm3 is needed. The exposure time required for bacterial count reduction is no less than 3 h. Despite certain limitations, Paraformaldehyde 97% tablets may be used for disinfecting. The objects to be disinfected should be neither too contaminated nor too soiled. The minimum period of exposure is 5 h, and 10 tablets/dm3 are necessary. Cold sterilization requires 10 tablets/dm3, too; but the exposure time ranges from 15 to 24 h. This method (which must be considered an expedient) should be employed only if the respective device or instrument cannot be sterilized by other sterilizing techniques. In any case, 80% relative air humidity is a must in the devices in which Paraformaldehyde 97% tablets are used.

Paraformaldehyde 97% is the solid form of liquid formaldehyde, formed by the polymerization of formaldehyde with a typical degree of polymerization of 8-100 units. Since Paraformaldehyde 97% is basically a condensed form of formaldehyde, it possesses the same characteristics but with a wider range of applications. Manufactured based on the latest technology to give good solubility, homogeneous prilled and low acid content, it is suitable for all ranges of application of Paraformaldehyde 97%.

Unlike granular or flake forms of Paraformaldehyde 97%, our prilled form of Paraformaldehyde 97% has higher quality consistency and higher solubility to meet with your quality requirement and save you processing time.

In coating applications, low acid content in Paraformaldehyde 97% is important for a greater gloss control and stability. Paraformaldehyde 97% made with very low acid content in a chemical resistant environment can prevent formation of acidic by-products.

In microbiology laboratories, fixation process (immunofluorescence) uses formalin 4% concentration. A blog by researchers mentioned that preparing this solution “fresh” from Paraformaldehyde 97% is better than using formalin that has been kept for some time. It is because more methylene glycol is present compared to its dimer and trimer oligomers and such solution of formalin 4% is absent of methanol.

Paraformaldehyde 97% can be used as a substitute of formalin to produce the resinous binding material, which is commonly used together with urea, melamine, phenol, resorcinol, tannin or other reactants in the manufacturing of particle board, fibreboard and plywood.

Use of Paraformaldehyde 97% in resin production offers many advantages as compared to aqueous formaldehyde:

Higher productivity from existing equipment and less water to be removed from the resin product.
It takes the form of prilled, is stable and very easy to store. Paraformaldehyde 97% storage is less expensive than the storage of formaldehyde solution, which requires expensive tanks and which may need stabilization or be kept warm.
Use of Paraformaldehyde 97% is convenient and safe. It avoids pollution arising from the disposal of the distillate obtained in the thermosetting resin production which is contaminated with organic matter.
Paraformaldehyde 97% does not need to be dissolved in water in order to take part in a chemical reaction.
It eliminates the risk of transporting liquid formalin, which is notoriously dangerous. Perfect for small uses straight from the bag.

Packaging & Handling of Paraformaldehyde 97%

- Polyethylene bag : 25 KG nett. Other Packaging sizes by request.

- Keep in a dry, cool and well-ventilated place. Provide sufficient air exchange and/or exhaust in work rooms. Paraformaldehyde 97% decomposes to formaldehyde which can build up in a shipping container depending on time and temperature during transit. The level of formaldehyde exposure may be instantaneously high when the shipping container is opened.

Storage of Paraformaldehyde 97%
Store in locked up. Location of storage should only be accesible to authorised personnel. Separate storage area from work place.

By Application of Paraformaldehyde 97%

Urea-Formaldehyde Resin
Phenolic Resin
Melamine Resin
Fumigation
Reagent for organic reactions
Coating
Pesticide
Disinfectant
Pharmaceuticals

Paraformaldehyde 97% (PFA) is a polymer of formaldehyde. Paraformaldehyde 97% itself is not a fixing agent, and needs to be broken down into its basic building block, formaldehyde. This can be done by heating or basic conditions until it becomes solubilized.

Formalin is the name for saturated (37%) formaldehyde solution. Beware though, some commercial formaldehyde solutions contain methanol to prevent polymerization (into Paraformaldehyde 97%). Since 100% formalin contains up to 15% of methanol as a stabilizer, it has a significant impact on cell fixation.

Methanol is a permeabilizing agent. It can interfere with the staining of membrane bound proteins, and can greatly influence staining of cytoskeletal proteins. For example, when staining cellular F-actin it is imperative to use a methanol-free formaldehyde fixative. This is because methanol can disrupt F-actin during the fixation process and prevent the binding of phalloidin conjugates.

"Pure" methanol-free formaldehyde can be made by heating the solid PFA. 4% Paraformaldehyde 97% is usually made in PBS or TBS at 70 °C with several drops of 5N NaOH to help clarify the solution. Prepare 4% Paraformaldehyde 97% solution in a chemical hood and then store in a refrigerator. Because the solution will re-polymerize during storage it is best to use immediately or within a few days.

In the presence of air and moisture, polymerization readily takes place in concentrated solutions at room temperatures to form paraformaldehyde, a solid mixture of linear polyoxymethylene glycols containing 90-99% formaldehyde.

Paraformaldehyde 97% is used in place of aqueous formaldehyde solutions, especially in applications where the presence of water interferes, e.g., in the plastics industry for the preparation of phenol, urea, and melamine resins, varnish resins, thermosets, and foundry resins. Other uses include the synthesis of organic products in the chemical and pharmaceutical industries (e.g., Prins reaction, chloromethylation, Mannich reaction), the production of textile auxiliaries (e.g., for crease-resistant finishes), and the preparation of disinfectants and deodorants.

Paraformaldehyde 97% is prepared industrially in continuously operated plants by concentrating aqueous formaldehyde solutions under vacuum conditions. ... /It/ is currently produced in several steps which are carried out at low pressure and various temperatures. Highly reactive formaldehyde is produced under vacuum conditions starting with solutions that contain 50 - 100 ppm of formic acid and also 1 - 15 ppm of metal formates where the metals have an atomic number of 23 - 30 (e.g., Mn, Co, and Cu). The solutions are processed in thin-layer evaporators and spray dryers.

Other techniques such as fractional condensation of the reaction gases in combination with the formaldehyde synthesis process and very rapid cooling of the gases are also applied. Alternatively, formaldehyde-containing gas is brought into contact with Paraformaldehyde 97% at a temperature that is above the dew point of the gas and below the decomposition temperature of Paraformaldehyde 97%. The product is obtained in the form of flakes when a highly concentrated formaldehyde solution is poured onto a heated metal surface. The hardened product is subsequently scraped off and thoroughly dried.

Paraformaldehyde 97% beads are produced by introducing a highly concentrated melt into a cooling liquid (e.g., benzene, toluene, cyclohexane). Acids and alkalis are also added; they apparently accelerate polymerization and lead to the formation of higher molecular mass but less reactive Paraformaldehyde 97%.

Highly soluble, highly reactive Paraformaldehyde 97% with a low degree of polymerization is very much in demand. It is produced from concentrated, aqueous - alcoholic formaldehyde solutions.

Dental Paraformaldehyde 97% Paste (Jap P). Past. Paraform. Dent. Paraformaldehyde 97% 35 g, procaine hydrochloride 35 g, hydrous wool fat 30 g.

The widmark test for the UV photometric determination of ethanol in blood and urine is described. Paraformaldehyde 97% can also be detected.

Paraformaldehyde 97% is designated as a hazardous substance under section 311(b)(2)(A) of the Federal Water Pollution Control Act and further regulated by the Clean Water Act Amendments of 1977 and 1978. These regulations apply to discharges of this substance. This designation includes any isomers and hydrates, as well as any solutions and mixtures containing this substance.

The Agency has completed its assessment of the residential, occupational and ecological risks associated with the use of pesticide products containing the active ingredient formaldehyde and Paraformaldehyde 97%. The Agency has determined that virtually all formaldehyde and Paraformaldehyde 97% containing products are eligible for reregistration provided that: 1) all risk mitigation measures are implemented; 2) current data gaps and confirmatory data needs are addressed; and 3) label amendments are made as described in Section V. Use in confined spaces such as closets is not eligible for registration because of the difficulty associated with ventilation of these spaces. ... Based on its evaluation of formaldehyde and Paraformaldehyde 97%, the Agency has determined that formaldehyde and Paraformaldehyde 97% products, unless labeled and used as specified in this document, would present risks inconsistent with FIFRA. Accordingly, should a registrant fail to implement the risk mitigation measures, submit confirmatory data as well as make the label changes identified in this document, the Agency may take regulatory action to address the risk concerns from the use of formaldehyde and Paraformaldehyde 97%. If all changes outlined in this document are fully complied with, then no risks of concern exist for the registered uses of formaldehyde and Paraformaldehyde 97% and the purposes of this determination.

The Agency has completed its assessment of the residential, occupational and ecological risks associated with the use of pesticide products containing the active ingredient formaldehyde and Paraformaldehyde 97%. The Agency has determined that virtually all formaldehyde and Paraformaldehyde 97% containing products are eligible for reregistration provided that: 1) all risk mitigation measures are implemented; 2) currentdata gaps and confirmatory data needs are addressed; and 3) label amendments are made as described in Section V. Use in confined spaces such as closets is not eligible for registration because of the difficulty associated with ventilation of these spaces. ... Based on its evaluation of formaldehyde and Paraformaldehyde 97%, the Agency has determined that formaldehyde and Paraformaldehyde 97% products, unless labeled and used as specified in this document, would present risks inconsistent with FIFRA. Accordingly, should a registrant fail to implement the risk mitigation measures, submit confirmatory data as well as make the label changes identified in this document, the Agency may take regulatory action to address the risk concerns from the use of formaldehyde and Paraformaldehyde 97%. If all changes outlined in this document are fully complied with, then no risks of concern exist for the registered uses of formaldehyde and Paraformaldehyde 97% and the purposes of this determination.

As the federal pesticide law FIFRA directs, EPA is conducting a comprehensive review of older pesticides to consider their health and environmental effects and make decisions about their continued use. Under this pesticide reregistration program, EPA examines newer health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether the use of the pesticide does not pose unreasonable risk in accordance to newer saftey standards, such as those described in the Food Quality Protection Act of 1996. Paraformaldehyde 97% is found on List A, which contains most pesticides that are used on foods and, hence, have a high potential for human exposure. List A consists of the 194 chemical cases (or 350 individual active ingredients) for which EPA issued registration standards prior to FIFRA '88. Case No: 0556; Pesticide type: fungicide, antimicrobial; Registration Standard Date: 05/31/88 PB88-231543; Case Status: OPP is reviewing data from the pesticide's producers regarding its human health and/or environmental effects, or OPP is determining the pesticide's eligibility for reregistration and developing the Reregistration Eligibility Decision (RED) document.; Active ingredient (AI): Paraformaldehyde 97%; AI Status: The producers of the pesticide have made commitments to conduct the studies and pay the fees required for reregistration, and are meeting those commitments in a timely manner.

Paraformaldehyde 97% is an indirect food additive for use only as a component of adhesives.

More decay was associated with tapholes in mature sugar maples (Acer saccharum) treated with a 250-mg Paraformaldehyde 97% pill than with control tapholes. This was apparent 20 months after treatment and at each successive examination to the final measurement at 56 months. Repeated use of Paraformaldehyde 97% leads to rapid development of decay in sugar maple.

Paraformaldehyde 97% is listed as a synthetic organic chemical which should be degradable by biological sewage treatment provided suitable acclimatization can be achieved.

Paraformaldehyde 97% is ubiquitous in the environment; it is an chemical that occurs in most life forms, including humans. It is formed naturally in the troposphere during the oxidation of hydrocarbons. Paraformaldehyde 97%'s production and use in the manufacture of a wide range of chemicals, such as resins, finding a variety of end uses such as wood products, plastics, and coatings may result in its release to the environment through various waste streams. Its use as a fumigant in agricultural premises and as a surface disinfectant in commercial premises and its use as a corrosion inhibitor in oil wells and release from slow-release fertilizers result in its direct release to the environment. If released to air, a vapor pressure of 3,890 mm Hg at 25 °C indicates Paraformaldehyde 97% will exist solely as a gas in the atmosphere. Gas-phase Paraformaldehyde 97% will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is 45 hrs. Paraformaldehyde 97% absorbs ultraviolet radiation at wavelengths of >360 nm and is susceptible to direct photolysis. Paraformaldehyde 97% has a direct photolysis half-life of 4.1 hours measured at sea-level and 40 degrees latitude. Paraformaldehyde 97% has been detected in rainwater and adsorbed to atmospheric particulates indicating it may be removed from the air by wet and dry deposition. If released to soil, Paraformaldehyde 97% is expected to have very high mobility based upon an estimated Koc of 8. In soil, Paraformaldehyde 97% gas can adsorb to clay minerals and interact with humic substances resulting in decreased mobility. Volatilization from moist soil surfaces is not expected to be an important fate process based upon a Henry's Law constant of 3.37X10-7 atm-cu m/mole. Paraformaldehyde 97% will volatilize from dry soil surfaces based upon its vapor pressure. Paraformaldehyde 97% has been found to be readily biodegradable in various screening tests. Utilizing the Japanese MITI test, 91% of the Theoretical BOD was reached in 2 weeks indicating that biodegradation is an important environmental fate process in soil and water. If released into water, Paraformaldehyde 97% is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. In a die-away test using water from a stagnant lake, degradation was complete in 30 and 40 hrs under aerobic and anaerobic conditions, respectively. The half-life of Paraformaldehyde 97% has been reported between 1-7 days in surface water and 2-14 days in groundwater, based on estimated aqueous aerobic biodegradation half lives. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's Henry's Law constant. An estimated BCF of 3 suggests the potential for bioconcentration in aquatic organisms is low. Paraformaldehyde 97% is not expected to undergo hydrolysis in the environment because of the lack of hydrolyzable functional groups. Occupational exposure to Paraformaldehyde 97% may occur through inhalation and dermal contact with this compound at workplaces where Paraformaldehyde 97% is produced or used. Monitoring data indicate that the general population may be exposed to Paraformaldehyde 97% via inhalation of ambient air (indoor and outdoor), inhalation of cigarette smoke, ingestion of food and possibly drinking water, and dermal contact with cosmetics, aerosol products and other consumer products containing Paraformaldehyde 97%. Concentrations of Paraformaldehyde 97% in outdoor and indoor air range from about 1 to 20 ug/cu m and 25 to 100 ug/cu m, respectively.

Paraformaldehyde 97% is ubiquitous in the environment; it is an endogenous chemical that occurs in most life forms, including humans. It is formed naturally in the troposphere during the oxidation of hydrocarbons, which react with hydroxyl radicals and ozone to form Paraformaldehyde 97% and other aldehydes, as intermediates in a series of reactions that ultimately lead to the formation of carbon monoxide and carbon dioxide, hydrogen and water. Of the hydrocarbons found in the troposphere, methane is the single most important source of Paraformaldehyde 97%. Terpenes and isoprene, emitted by foliage, react with hydroxyl radicals, forming Paraformaldehyde 97% as an intermediate product. Because of their short half-life, these potentially important sources of Paraformaldehyde 97% are important only in the vicinity of vegetation. Paraformaldehyde 97% is one of the volatile compounds formed in the early stages of decomposition of plant residues in the soil. Paraformaldehyde 97% occurs naturally in fruits and other foods. Other sources are forest fires, animal wastes, microbial products of biological systems, and plant volatiles(2,3). Paraformaldehyde 97% can also be formed in seawater by photochemical processes. However, calculations of sea-air exchange indicates that this process is probably a minor source for Paraformaldehyde 97% in the sea.

Paraformaldehyde 97%'s production and use in the manufacture of a wide range of chemicals, such as resins, finding a variety of end uses such as wood products, plastics, and coatings may result in its release to the environment through various waste streams. Its use as a fumigant in agricultural premises and as a surface disinfectant in commercial premises and its use as a corrosion inhibitor in oil wells and release from slow-release fertilizers result in its direct release to the environment. Paraformaldehyde 97% is formed by the incomplete combustion of many organic substances and is present in coal and wood smoke and in cigarette smoke.

Based on a classification scheme, an estimated Koc value of 8, determined from a log Kow of 0.35 and a regression-derived equation, indicates that Paraformaldehyde 97% is expected to have very high mobility in soil. In soil, Paraformaldehyde 97% gas can adsorb to clay minerals and interact with humic substances resulting in decreased mobility. Volatilization of Paraformaldehyde 97% from moist soil surfaces is not expected to be an important fate process given a Henry's Law constant of 3.37X10-7 atm-cu m/mole. Paraformaldehyde 97% is expected to volatilize from dry soil surfaces based upon a vapor pressure of 3,890 mm Hg at 25 °C. Paraformaldehyde 97% has been found to be readily biodegradable in various screening tests. Utilizing the Japanese MITI test, 91% of the Theoretical BOD was reached in 2 weeks indicating that biodegradation is an important environmental fate process in soil.

According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere, Paraformaldehyde 97%, which has a vapor pressure of 3,890 mm Hg at 25 °C, will exist in the gas phase in the ambient atmosphere. Gas-phase Paraformaldehyde 97% is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is 45 hrs, calculated from its rate constant of 8.50X10-12 cu cm/molecule-sec at 25 °C. The hydroxy radical initiated oxidation of Paraformaldehyde 97% also occurs in cloud droplets to form formic acid, a component of acid rain. Paraformaldehyde 97% absorbs ultraviolet radiation at wavelengths of >360 nm; therefore, Paraformaldehyde 97% may be susceptible to direct photolysis by sunlight. Direct photolysis half-lives of 1 to 4.1 hours have been measured using sunlight; the 4.1 hour half-life was measured at sea-level and 40 degrees latitude. Gas-phase Paraformaldehyde 97% is also degraded in the atmosphere by reaction with atmospheric nitrate radicals; the half-life for this reaction in air is about 57 days, calculated from its rate constant of 5.60X10-16 cu cm/molecule-sec at 25 °C. Paraformaldehyde 97% has been detected in rainwater, therefore, it may be removed from the air by wet deposition. In addition, in a study of the Paraformaldehyde 97% content of atmospheric aerosol, it was demonstrated that up to 5% of the total atmospheric content of Paraformaldehyde 97% can be associated with particulate matter due to vapor adsorption to particulates; therefore, particulate-phase Paraformaldehyde 97% may be removed from the air by wet and dry deposition.

The rate constant for the gas-phase reaction of Paraformaldehyde 97% with photochemically-produced hydroxyl radicals is 8.50X10-12 cu cm/molecule-sec at 25 °C. This corresponds to an atmospheric half-life of about 45 hrs at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm. The hydroxy radical initiated oxidation of Paraformaldehyde 97% also occurs in cloud droplets to form formic acid, a component of acid rain. Paraformaldehyde 97% has a reported direct photolysis half-life of 6 hrs in simulated sunlight. Direct photolysis half-lives of 1 to 4.1 hours have been measured using sunlight; the 4.1 hour half-life was measured at sea-level and 40 degrees latitude. There are two photolytic pathways, one producing hydrogen gas and carbon monoxide, and the other producing H and HCO radicals. The rate constant for the gas-phase reaction of Paraformaldehyde 97% with atmospheric nitrate radicals is 5.60X10-16 cu cm/molecule-sec at 25 °C; this corresponds to an atmospheric half-life of 57 days at averaged atmospheric concentration of 2.5X10+8 nitrate radicals per cu cm. In water, Paraformaldehyde 97% undergoes essentially complete hydration to yield the gem-diol, methylene glycol. This hydrate does not have a chromophore that is capable of absorbing sunlight and photolytically decomposing. Hydrated Paraformaldehyde 97% is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions. Solutions containing Paraformaldehyde 97% are unstable, both oxidizing slowly to form formic acid and polymerizing to form oligomers. In the presence of air and moisture, polymerization readily takes place in concentrated solutions at room temperatures to form paraParaformaldehyde 97%, a solid mixture of linear polyoxymethylene glycols containing 90-99% Paraformaldehyde 97%.

The Koc of Paraformaldehyde 97% is estimated as 8, using a log Kow of 0.35 and a regression-derived equation. According to a classification scheme, this estimated Koc value suggests that Paraformaldehyde 97% is expected to have very high mobility in soil. Paraformaldehyde 97% gas adsorbs on clay minerals to a degree at high gas concentrations which is an important quality in its use as a soil fumigant. In addition, Paraformaldehyde 97% may interact with humic substances in soil resulting in decreased mobility.

The Henry's Law constant for Paraformaldehyde 97% is 3.37X10-7 atm-cu m/mole. This Henry's Law constant indicates that Paraformaldehyde 97% is expected to be essentially nonvolatile from water surfaces. Paraformaldehyde 97%'s Henry's Law constant indicates that volatilization from moist soil surfaces is not expected to be an important fate process. Paraformaldehyde 97% is a gas under ambient conditions, therefore, volatilization from dry soil surfaces will occur.