1. Polyacrylamide (PAM) is not classified as a monitored chemical under the Chemical Weapons Convention; it is environmentally harmless and exhibits very low toxicity to the human body.
2. The U.S. Food and Drug Administration (FDA) considers PAM and its hydrolysates to be of low toxicity or non-toxic.
3. The toxicity of PAM primarily stems from residual acrylamide monomers and toxic metals that may be entrained during the manufacturing process.
4. Acrylamide is a neurotoxin that can cause damage to the nervous system; symptoms of poisoning include muscle weakness and motor incoordination.
5. Consequently, health authorities in various countries have established regulations regarding the permissible levels of residual acrylamide in industrial polyacrylamide products, typically ranging from 0.5% to 0.05%.
6. In general water purification processes, the residual acrylamide content is typically required to be below 0.2%; for the treatment of direct drinking water, this limit is set even lower, at less than 0.05%.
7. Standards established by international health organizations in 1985 indicate that when the residual acrylamide monomer (AM) content in PAM is controlled to below 0.05%-and the dosage is appropriately regulated-the concentration in the treated water will remain below 0.25 μg/L, thereby meeting the drinking water standards of most countries.
8. Currently, major countries in Europe and North America generally mandate that the residual AM content in PAM used for drinking water treatment and food-related applications must be below 0.05%, in addition to requiring strict control over the dosage of PAM used.
9. The situation regarding cationic PAM is more complex, as the amino-based and other functional groups introduced into its structure may exhibit higher toxicity than those found in anionic or non-ionic variants; its chronic toxicity remains the subject of ongoing research.
10. For flocculants utilized in drinking water treatment, the use of food-grade products is essential to ensure safety.
11. The *Implementation Manual for Water Supply and Drainage Standards and Specifications* explicitly stipulates that, for polyacrylamide applications, the concentration used should exceed 0.1 mg/L in instances of infrequent use, whereas it should remain below 0.1 mg/L in instances of frequent or continuous use.
12. In the context of using polyacrylamide as a flocculant aid in water treatment processes, the aforementioned standard values may be adopted as the maximum permissible dosage; furthermore, the selection of food-grade PAM products with low residual levels serves to guarantee the hygienic safety of the drinking water produced.
13. For instance, a certain water treatment plant utilizes PAM as a coagulation aid; with a maximum dosage of 0.09 mg/L-using a food-grade product-no acrylamide monomers were detected in either the filter effluent or the finished tap water leaving the plant.
14. Provided that product quality and dosage levels are properly controlled, the use of PAM-assisted coagulation processes is safe from a drinking water hygiene perspective.
15. It is anticipated that, as the issue of water scarcity due to poor water quality becomes more widespread and public expectations regarding drinking water quality rise, the application of PAM-based organic products in my country's water treatment sector will gradually expand.
16. Between 1997 and 1999, a specific water supply company saw its PAM consumption increase approximately eightfold; the number of water treatment plants utilizing the product rose from one to six, with applications spanning coagulation, coagulation assistance, and filtration assistance.
17. Dosing PAM at levels between 0.015 and 0.05 mg/L can enhance filter bed performance, boosting water production capacity by 10% to 16%. Although this may result in increased head loss, backwash duration, and backwash intensity, the economic benefits of using PAM as a filtration aid are still considered cost-effective.
18. The use of PAM as a filtration aid helps prevent algae from penetrating the filter beds and, in the event of sudden operational emergencies, ensures the quality of the filtered water.
19. The application of polyacrylamide-based organic products in water treatment is gaining increasing acceptance among water supply enterprises, owing to their advantages in enhancing flocculation, improving filtration efficiency, upgrading water quality, increasing water output, and reducing costs.
20. Research and development regarding the application of PAM in the field of drinking water treatment are ongoing, and the prospects for its future use remain optimistic.
21. Polyacrylamide products themselves are fundamentally non-toxic; upon entering the human body, the vast majority is rapidly excreted within a short period, with very little being absorbed by the digestive tract.
22. Most commercial PAM products do not irritate the skin; while certain hydrolyzed variants may contain residual alkalinity-which could cause irritation upon repeated or prolonged contact-manufacturers and distributors need not be overly concerned about potential hazards during handling.
