Effects of TiO2 nanoparticles and sunscreens on coastal marine microalgae: Ultraviolet radiation is key variable for toxicity assessment.

Given the large numbers of sunbathers on beaches, sunscreen compounds are being released into the coastal aquatic environment in significant amounts. Until now the effect of these potential pollutants on microbiota has been not well-known. Phytoplankton is a key component of the microbiota community. It forms the basis of the aquatic trophic networks, and any change in the natural population of phytoplankton can affect the structure of aquatic biota. This paper describes an experiment performed outdoors (in natural sunlight conditions including ultraviolet radiation (UVR) and with UVR blocked) on mixed microalgae populations (four species from different key marine taxonomic groups, Nannochloropsis gaditana, Chaetoceros gracilis, Pleurochrysis roscoffensis and Amphidinium carterae), for three days, exposed to a range of concentrations of three commercial sunscreens (with variable TiO2 concentrations: highest concentration for sunscreen C, followed by sunscreen A; and sunscreen B did not contain TiO2 in its composition). With regard to UVR effect, in the absence of sunscreens, the most sensitive species is the centric diatom, Chaetoceros gracilis, and the least is Nannochloropsis gaditana; this last species presented the same behavior in the absence of UVR and with high sunscreen concentrations. The toxicity gradient obtained for sunscreens and nanoparticles under UVR is: TiO2 NPs>Sunscreen C>Sunscreen A>Sunscreen B. The differential sensitivity of microalgae to sunscreens and TiO2 NPs can produce a change in the dynamics of phytoplankton populations and provoke undesirable ecological effects (such as giving dinoflagellates more prominence). The effects of UVR, commonly neglected in bioassays, could alter the results in important ways and should be considered when performing environmentally-relevant bioassays. The toxicity mediated by hydrogen peroxide production associated with the concentration of TiO2 NPs cannot be considered the only factor responsible for the toxicity: the organic compounds in the sunscreens must also be taken into account.

[Outcome of acute lymphoblastic leukemia in the pediatric age group over a 29-year period (1972-2000)]. / Evolución de la leucemia linfoblástica aguda en la edad pediátrica en 29 años (1972-2000).

OBJECTIVE: To evaluate the progress achieved in the treatment of acute lymphoblastic leukemia (ALL) in our hospital. MATERIAL AND METHODS: A total of 235 patients diagnosed with ALL in the central region of Cuba from 1972 to 2000 were included. Four groups were considered according to the diagnostic period and treatment protocol. Group 1 was composed of 20 patients who did not receive a uniform treatment regimen. The remaining groups were treated with different protocols of the Latin American Group for Malignant Hemopathy Therapy (Glathem). Group 2 was treated with less aggressive classical regimens from the 1970s, and groups 3 and 4 received more aggressive regimens, type Berlin-Frankfurt-Munster (BFM). Intravenous high-dose methotrexate was used in group 4 but not in group 3. Classification by prognostic groups was based on age and leukocyte count. RESULTS: Of 215 patients included in the Glathem protocols, remission occurred in 197 (91.6%). Overall survival in the distinct treatment groups progressively increased during the study period, from a 5-year survival of 15% in group 1 to 72% in group 4. Event-free survival in patients included in the Glathem protocols increased from 42% in group 2 (classical protocols) to 68.7% in the BFM protocols (groups 3 and 4). Significant differences were found among the different treatment and prognostic groups considered. CONCLUSIONS: During the period analyzed, survival in children with ALL progressively increased in parallel with improved treatment regimens. These results demonstrate the importance of well-programmed polychemotherapy to achieve prolonged survival and a high percentage of cure in this disease.