Research and development, where people are exposed to nanomaterials

OBJECTIVES: Many nanomaterials (materials with structures smaller than 100 nm) have chemical, physical and bioactive characteristics of interest for novel applications. Considerable research efforts have been launched in this field. This study aimed to study exposure scenarios commonly encountered in research settings. METHODS: We studied one of the leading Swiss universities and first identified all research units dealing with nanomaterials. After a preliminary evaluation of quantities and process types used, a detailed analysis was conducted in units where more than a few micrograms were used per week. RESULTS: In the investigated laboratories, background levels were usually low and in the range of a few thousand particles per cubic centimeter. Powder applications resulted in concentrations of 10,000 to 100,000 particles/cm(3) when measured inside fume hoods, but there were no or mostly minimal increases in the breathing zone of researchers. Mostly low exposures were observed for activities involving liquid applications. However, centrifugation and lyophilization of nanoparticle-containing solutions resulted in high particle number levels (up to 300,000 particles/cm(3)) in work spaces where researchers did not always wear respiratory protection. No significant increases were found for processes involving nanoparticles bound to surfaces, nor were they found in laboratories that were visualizing properties and structure of small amounts of nanomaterials. CONCLUSIONS: Research activities in modern laboratories equipped with control techniques were associated with minimal releases of nanomaterials into the working space. However, the focus should not only be on processes involving nanopowders but should also be on processes involving nanoparticle-containing liquids, especially if the work involves physical agitation, aerosolization or drying of the liquids.

Seletividade de agrotóxicos usados na cultura da macieira a Neoseiulus Californicus (McGregor) (Acari: Phytoseiidae)1

Objetivou-se avaliar os efeitos secundários dos principais agrotóxicos utilizados em macieira sobre adultos e imaturos de Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). Os testes foram conduzidos em laboratório, utilizando as doses dos produtos recomendadas para a cultura e o método de contato e residual com pulverização em superfície de folha. Foram testados tebufenozida, fosmete, metidationa, clorpirifós, abamectina, fenpiroximato, piridabem, captana, mancozebe (duas dosagens) e ditianona. Para o cálculo do efeito total (E%) sobre os adultos, avaliaram-se a mortalidade, a oviposição e a viabilidade dos ovos, e para os imaturos, somente a mortalidade. Os resultados do E% foram avaliados 96 horas após a pulverização. Os produtos foram classificados quanto ao efeito total (E%) de toxicidade proposta pela IOBC/WPRS. Fosmete, tebufenozida e metidationa foram inócuos; abamectina, fenpiroximato, clorpirifós, captana, mancozebe (nas duas dosagens testadas) e ditianona foram levemente nocivos, e piridabem foi moderadamente nocivo aos adultos de N. californicus. O fungicida mancozebe, na maior dosagem (320g,i.a./100L), foi o que mais afetou o ácaro predador. Quanto à seletividade dos agrotóxicos aos imaturos, constatouse que abamectina e piridabem foram moderadamente nocivos, e os demais foram inócuos. Nenhum produto foi classificado como nocivo, evidenciando a tolerância de N. californicus a estes agrotóxicos. Estes resultados permitem uma escolha e manejo mais adequado para os agrotóxicos utilizados nos pomares comerciais de macieira, de forma que a presença deste ácaro predador exerça pressão de controle do ácaro-vermelho.

Prevalence of cerebral amyloid pathology in persons without dementia: a meta-analysis.

IMPORTANCE: Cerebral amyloid-β aggregation is an early pathological event in Alzheimer disease (AD), starting decades before dementia onset. Estimates of the prevalence of amyloid pathology in persons without dementia are needed to understand the development of AD and to design prevention studies. OBJECTIVE: To use individual participant data meta-analysis to estimate the prevalence of amyloid pathology as measured with biomarkers in participants with normal cognition, subjective cognitive impairment (SCI), or mild cognitive impairment (MCI). DATA SOURCES: Relevant biomarker studies identified by searching studies published before April 2015 using the MEDLINE and Web of Science databases and through personal communication with investigators. STUDY SELECTION: Studies were included if they provided individual participant data for participants without dementia and used an a priori defined cutoff for amyloid positivity. DATA EXTRACTION AND SYNTHESIS: Individual records were provided for 2914 participants with normal cognition, 697 with SCI, and 3972 with MCI aged 18 to 100 years from 55 studies. MAIN OUTCOMES AND MEASURES: Prevalence of amyloid pathology on positron emission tomography or in cerebrospinal fluid according to AD risk factors (age, apolipoprotein E [APOE] genotype, sex, and education) estimated by generalized estimating equations. RESULTS: The prevalence of amyloid pathology increased from age 50 to 90 years from 10% (95% CI, 8%-13%) to 44% (95% CI, 37%-51%) among participants with normal cognition; from 12% (95% CI, 8%-18%) to 43% (95% CI, 32%-55%) among patients with SCI; and from 27% (95% CI, 23%-32%) to 71% (95% CI, 66%-76%) among patients with MCI. APOE-ε4 carriers had 2 to 3 times higher prevalence estimates than noncarriers. The age at which 15% of the participants with normal cognition were amyloid positive was approximately 40 years for APOE ε4ε4 carriers, 50 years for ε2ε4 carriers, 55 years for ε3ε4 carriers, 65 years for ε3ε3 carriers, and 95 years for ε2ε3 carriers. Amyloid positivity was more common in highly educated participants but not associated with sex or biomarker modality. CONCLUSIONS AND RELEVANCE: Among persons without dementia, the prevalence of cerebral amyloid pathology as determined by positron emission tomography or cerebrospinal fluid findings was associated with age, APOE genotype, and presence of cognitive impairment. These findings suggest a 20- to 30-year interval between first development of amyloid positivity and onset of dementia.