Sodium and potassium alginates extracted from Macrocystis pyrifera algae for use in dental impression materials

 Sodium and potassium alginates were extracted at the pilot plant scale from the giant kelp, Macrocystis pyrifera, from Bahía Tortugas, Baja California Sur, Mexico. Alginates were coded as S1, S2 and S3 for sodium alginate, and as P1, P2 and P3 for potassium alginate. The average viscosities of the sodium and potassium alginates in aqueous 1% solution were 58, 145 and 506 mPa s, and 48, 155 and 200 mPa s, respectively. Results showed that dental impresion material prepared with sodium alginate with extra low viscosities (S1 = 58 mPa s) and low viscosities (S2 = 145 m Pa s) did not form gels, the material prepared with medium viscosity (S3 = 506 mPa s) produced a gel type II (regular set) in 70% of the 10 formulations experimented, and the material prepared with potassium alginate with extra low viscosity (P1 = 48 mPa s) produced a gel type II in 90% of the formulations. Using potassium alginate with low viscosity (P2 = 155 mPa s), 90% of the formulations were type I (fast set), and using potassium alginate with medium viscosity (P3 = 200 mPa s), 80% of the formulations were type I. The highest compressive strength was obtained using sodium alginate of 506 mPa s and the three potassium alginates experimented at 25% concentration, with values of 2474, 1209, 2101 and 2124 g cm–2 for S3, P1, P2 and P3 alginates, respectively. The elasticity order of formulation with 25% alginates compared with a commercial product (Jeltrate®) was as follows: Jeltrate® > P2 > S3 > P3 > P1. It was concluded that S3, P1, P2 and P3 alginates have good potential for use in the production of dental impression materials

Occurrence and quantitative microbial risk assessment of Cryptosporidium and Giardia in soil and air samples

Background: Cryptosporidium oocysts and Giardia cysts can be transmitted by the fecal–oral route and may cause gastrointestinal parasitic zoonoses. These zoonoses are common in rural zones due to the parasites being harbored in fecally contaminated soil. This study assessed the risk of illness (giardiasis and cryptosporidiosis) from inhaling and/or ingesting soil and/or airborne dust in Potam, Mexico. Methods: To assess the risk of infection, Quantitative Microbial Risk Assessment (QMRA) was employed, with the following steps: (1) hazard identification, (2) hazard exposure, (3) dose–response, and (4) risk characterization. Results: Cryptosporidium oocysts and Giardia cysts were observed in 52% and 57%, respectively, of total soil samples (n = 21), and in 60% and 80%, respectively, of air samples (n = 12). The calculated annual risks were higher than 9.9 × 10−1 for both parasites in both types of sample. Conclusions: Soil and air inhalation and/or ingestion are important vehicles for these parasites. To our knowledge, the results obtained in the present study represent the first QMRAs for cryptosporidiosis and giardiasis due to soil and air inhalation/ingestion in Mexico. In addition, this is the first evidence of the microbial air quality around these parasites in rural zones