Elisabete Fernandes Albuquerque Palermo

Systemic levels of metallic ions released from orthodontic mini-implants

INTRODUCTION Orthodontic mini-implants are a potential source of metallic ions to the human body because of the corrosion of titanium (Ti) alloy in body fluids. The purpose of this study was to gauge the concentration of Ti, aluminum (Al), and vanadium (V), as a function of time, in the kidneys, livers, and lungs of rabbits that had Ti-6Al-4V alloy orthodontic mini-implants placed in their tibia. METHODS Twenty-three New Zealand rabbits were randomly divided into 4 groups: control, 1 week, 4 weeks, and 12 weeks. Four orthodontic mini-implants were placed in the left proximal tibia of 18 rabbits. Five control rabbits had no orthodontic mini-implants. After 1, 4, and 12 weeks, the rabbits were killed, and the selected tissues were extracted and prepared for analysis by graphite furnace atomic absorption spectrophotometry. RESULTS Low amounts of Ti, Al, and V were detectable in the 1-week, 4-weeks, and 12-weeks groups, confirming that release of these metals from the mini-implants occurs, with diffusion and accumulation in remote organs. CONCLUSIONS Despite the tendency of ion release when using the Ti alloy as orthodontic mini-implants, the amounts of metals detected were significantly below the average intake of these elements through food and drink and did not reach toxic concentrations.

Mercury distribution in different tissues and trophic levels of fish from a tropical reservoir, Brazil

Concentrations of organic (OrgHg) and inorganic mercury (InorgHg) were assessed in different fish tissues (liver, muscle, kidney, gut and gonads) and trophic levels collected in an impacted tropical reservoir in southeastern Brazil. Organic mercury concentrations in muscle were remarkably higher in the carnivorous species Hoplias malabaricus and Oligosarcus hepsetus. The ratios of OrgHg in relation to total mercury (%OrgHg) in muscle also varied according to the species trophic level: 93% for carnivores, 84% for omnivores, 73% for algivores/planktivores and 58% for detritivores. The %OrgHg in the gut tissue of carnivores (78%) was much higher than that found in omnivores (30%), possibly reflecting a process of trophic biomagnification in the reservoir. On the other hand, the InorgHg concentrations in muscle decreased with the trophic level increase, suggesting that this form of mercury did not biomagnify through the food web. Gonads contained the least total mercury, and approximately all of this mercury was represented by the organic form (83 to 98%). The kidney and the liver of all fish species contained less than 50% OrgHg. We suggest that the low %OrgHg in the liver is related to different capacities or strategies of OrgHg detoxification by the fish.

Methyl and total mercury found in two man-made Amazonian Reservoirs

Metilmercurio (MeHg) e mercurio total (Hg) foram determinados em amostras de agua e peixe coletadas em dois reservatorios da Amazonia Brasileira, que apresentam diferentes caracteristicas limnologicas e ecologicas. As amostras de agua de Tucurui, reservatorio mesotrofico com aguas claras, apresentaram a concentracao de Hg (12,7 ± 8,4 ng L-1) superior a encontrada em Balbina (2,2 ± 0,5 ng L-1), que e um reservatorio oligotrofico com aguas escuras. Nem Cichla spp. (peixe piscivoro), nem Geophagus surinamensis (peixe onivoro) apresentaram diferenca significativa nas concentracoes normalizadas pelo comprimento de MeHg e Hg no musculo, entre os dois reservatorios. MeHg e Hg aumentaram com o peso e o comprimento do Cichla spp. e, tambem, com o posicionamento trofico na cadeia alimentar. O fator de bioconcentracao (FBC) do Hg aumentou com o nivel trofico dos peixes, do onivoro (103) para o piscivoro (104). Os peixes de Balbina, ecossistema naturalmente rico em materia orgânica dissolvida, apresentaram maior FBC. Nao somente as diferentes caracteristicas limnologicas e ecologicas, mas tambem o habito alimentar dos peixes parecem ter influencia nas concentracoes de mercurio nestes organismos.