Enrique Gaona

Association between Urine Fluoride and Dental Fluorosis as a Toxicity Factor in a Rural Community in the State of San Luis Potosi

Objective. The aim of this study is to investigate urine fluoride concentration as a toxicity factor in a rural community in the state of San Luis Potosi, Mexico. Materials and Methods. A sample of 111 children exposed to high concentrations of fluoride in drinking water (4.13 mg/L) was evaluated. Fluoride exposure was determined by measuring urine fluoride concentration using the potentiometric method with an ion selective electrode. The diagnosis of dental fluorosis was performed by clinical examination, and the severity of damage was determined using Deans index and the Thylstrup-Fejerskov (TF) index. Results. The range of exposure in the study population, evaluated through the fluoride content in urine, was 1.1 to 5.9 mg/L, with a mean of 3.14 ± 1.09 mg/L. Dental fluorosis was present in all subjects, of which 95% had severe cases. Higher urine fluoride levels and greater degrees of severity occurred in older children. Conclusions. The results show that dental fluorosis was determined by the presence of fluoride exposure finding a high positive correlation between the severity of fluorosis and urine fluoride concentration and the years of exposure suggested a cumulative effect.

Prevalence of anti-T canis antibodies in stray dogs in Mexico City

UNLABELLED Toxocara canis is a common intestinal helminth found in dogs. In humans, it is a cause of Visceral Larva Migrans (VLM), a zoonosis rarely studied in Mexico. The aim of this study is to examine, by means of the indirect haemaglutination test (IHAT), the prevalence of antibodies of T. canis in the serum of stray dogs in Mexico City. METHODS AND MATERIALS 141 stray dog serum samples from three different districts of the city were analyzed: Iztacalco (49), Iztapalapa (49) and Coyoacan (43). In each location three study groups were formed. Group I with 35 dogs (less than a year old), Group II with 91 dogs (ages 1<or=n<6) and Group III with 15 dogs (ages 6 and over). An extract of raw adult T. canis worms was used as an antigen. Finally, a modified version of Boydens IHA serological test was carried out. RESULTS Out of the 141 sera, 94 (40 males and 54 females) proved positive (dilution titres of from 1:32 to 1:4096) with a global infection prevalence of 66.7%. The frequency of infected dogs in Iztacalco was 61.2%, 51% in Iztapalapa and 90.7% in Coyoacan. The largest seroreactivity was found in Group II (ages 1-6) with 61 positive tests and a total frequency of 43.3%. CONCLUSIONS The high seroprevalence of anti-T. canis antibodies found in the dogs of the study population is an indicator of the contact which exists between these animals and the parasite. This is the result of the high degree of contamination of the soil of Mexico City with the parasites eggs. Paradoxically, Coyoacan, with more green areas, is also the most polluted municipality. Statistical analysis confirms this. Dogs seek green areas to defecate. There exists a serious risk for the population of being infected with Visceral larva migrans.

Drinking Water Fluoride Levels for a City in Northern Mexico (Durango) Determined Using a Direct Electrochemical Method and Their Potential Effects on Oral Health

Fluoride is ingested primarily through consuming drinking water. When drinking water contains fluoride concentrations >0.7 parts per million (ppm), consuming such water can be toxic to the human body; this toxicity is called “fluorosis.” Therefore, it is critical to determine the fluoride concentrations in drinking water. The objective of this study was to determine the fluoride concentration in the drinking water of the city of Durango. The wells that supply the drinking water distribution system for the city of Durango were studied. One hundred eighty-nine (189) water samples were analyzed, and the fluoride concentration in each sample was quantified as established by the law NMX-AA-077-SCFI-2001. The fluoride concentrations in such samples varied between 2.22 and 7.23 ppm with a 4.313 ± 1.318 ppm mean concentration. The highest values were observed in the northern area of the city, with a 5.001 ± 2.669 ppm mean value. The samples produced values that exceeded the national standard for fluoride in drinking water. Chronic exposure to fluoride at such concentrations produces harmful health effects, the first sign of which is dental fluorosis. Therefore, it is essential that the government authorities implement water defluoridation programs and take preventative measures to reduce the ingestion of this toxic halogen.

TL dosimetry for quality control of CR mammography imaging systems

The aim of this work is to estimate the average glandular dose with thermoluminescent (TL) dosimetry and comparison with quality imaging in computed radiography (CR) mammography. For a measuring dose, the Food and Drug Administration (FDA) and the American College of Radiology (ACR) use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, full field digital mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium flourohalide. We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated X-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose greater than 3.0 mGy without demonstrating improved image quality. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement for X-rays with a HVL (0.35–0.38 mmAl) and kVp (24–26) used in quality control procedures with ACR Mammography Accreditation Phantom.

Quality Imaging — Comparison of CR Mammography with Screen‐Film Mammography

The aim of this work is a quality imaging comparison of CR mammography images printed to film by a laser printer with screen‐film mammography. A Giotto and Elscintec dedicated mammography units with fully automatic exposure and a nominal large focal spot size of 0.3 mm were used for the image acquisition of phantoms in screen‐film mammography. Four CR mammography units from two different manufacturers and three dedicated x‐ray mammography units with fully automatic exposure and a nominal large focal spot size of 0.3 mm were used for the image acquisition of phantoms in CR mammography. The tests quality image included an assessment of system resolution, scoring phantom images, Artifacts, mean optical density and density difference (contrast). In this study, screen‐film mammography with a quality control program offers a significantly greater level of quality image relative to CR mammography images printed on film.

Initial Image Quality and Clinical Experience with New CR Digital Mammography System: A Phantom and Clinical Study

The goal of the study was to evaluate the first CR digital mammography system (® Konica‐Minolta) in Mexico in clinical routine for cancer detection in a screening population and to determine if high resolution CR digital imaging is equivalent to state‐of‐the‐art screen‐film imaging. The mammograms were evaluated by two observers with cytological or histological confirmation for BIRADS 3, 4 and 5. Contrast, exposure and artifacts of the images were evaluated. Different details like skin, retromamillary space and parenchymal structures were judged. The detectability of microcalcifications and lesions were compared and correlated to histology. The difference in sensitivity of CR Mammography (CRM) and Screen Film Mammography (SFM) was not statistically significant. However, CRM had a significantly lower recall rate, and the lesion detection was equal or superior to conventional images. There is no significant difference in the number of microcalcifications and highly suspicious calcifications were equally det...

Occupational Exposure to Diagnostic Radiology in Workers without Training in Radiation Safety

The physicians, technicians, nurses, and others involved in radiation areas constitute the largest group of workers occupationally exposed to man‐made sources of radiation. Personnel radiation exposure must be monitored for safety and regulatory considerations, this assessment may need to be made over a period of one month or several months. The purpose of this study was to carry out an exploratory survey of occupational exposures associated with diagnostic radiology. The personnel dosimeters used in this study were thermoluminiscent dosimeters (TLDs). The reported number of monitored workers was 110 of different departments of radiology of the Mexican Republic without education in radiation safety, included general fluoscopic/radiographic imaging, computed tomography and mammography procedures. Physicians and X‐ray technologist in diagnostic radiology receive an average annual effective dose of 2.9 mSv with range from 0.18 to 5.64 mSv. The average level of occupational exposures is generally similar to t...