Overweight, Obesity, Hypertriglyceridemia, and Insulin Resistance Are Positively Associated with High Serum Copper Levels in Mexican Adults

Recently, the role of trace elements in the pathophysiology of obesity, insulin resistance (IR), and metabolic diseases has been explored. In this cross-sectional study, we aimed to assess the association of overweight, obesity, and cardiometabolic traits with serum copper (Cu) levels in 346 Mexican adults. Serum Cu level was measured by inductively coupled plasma mass spectrometry (ICP-MS). Anthropometrical data were collected, and biochemical parameters were measured. The triglyceride-glucose (TyG) index was used as a surrogate marker to evaluate IR. Overweight and obesity status was positively associated with the serum Cu level (β = 19.434 ± 7.309, p = 0.008). Serum Cu level was observed to have a positive association with serum triglycerides level (β = 0.160 ± 0.045, p < 0.001) and TyG (β = 0.001 ± 0.001, p < 0.001). Additionally, high serum Cu level was positively associated with overweight and obesity status (odds ratio [OR] = 1.9, 95% confidence interval [95% CI] 1.1-3.4, p = 0.014), hypertriglyceridemia (OR = 3.0, 95% CI 1.7-5.3, p < 0.001), and IR (OR = 2.6, 95% CI 1.4-4.6, p = 0.001). In conclusion, our results suggest that overweight, obesity, hypertriglyceridemia, and IR are positively associated with serum Cu levels in Mexican adults.

Occupational Lead Exposure Ototoxicity Evaluated With Distortion-Product Otoacoustic Emissions

OBJECTIVES

To evaluate the extent of hearing loss among pottery workers in Mexico exposed to lead.

DESIGN

The authors conducted a cross-sectional study including 315 adult pottery workers. Auditory function was evaluated by air conduction pure-tone audiometry (pure-tone average) and distortion-product otoacoustic emission (DPOAE) levels (amplitude and signal-to-noise ratio). Lead exposure was assessed with a single blood sample test and classified as low, medium, and high according to blood lead tertiles. Logistic regression models were calculated for the association between blood lead levels, pure-tone average, and DPOAE records.

RESULTS

Median (25th-75th) blood lead levels were 14 μg/dL (7.5-22.6 μg/dL). The audiometric pattern and DPOAE records were similar across blood lead levels groups in all frequencies, and no statistically significant differences were found. Adjusted logistic regression models showed no increase in the odds for hearing thresholds >25 dB (HL) and DPOAE absence associated with blood lead levels, and no dose-response pattern was observed ( p > 0.05).

CONCLUSIONS

Given the results from this cross-sectional study, no association was found between blood lead levels and hearing loss assessed with DPOAE. Future longitudinal work should consider chronic lead exposure estimates among underrepresented populations, which can potentially inform safer work practices to minimize the risk of ototoxicity.

Relationship between urinary biomarkers of early kidney damage and exposure to inorganic toxins in a pediatric population of Apizaco, Tlaxcala, Mexico

BACKGROUND

In recent years, chronic kidney disease has increased in the pediatric population and has been related to environmental factors. In the diagnosis of kidney damage, in addition to the traditional parameters, early kidney damage biomarkers, such as kidney injury molecule 1, cystatin C, and osteopontin, among others, have been implemented as predictors of early pathological processes.

OBJECTIVE

This study aimed to evaluate the relationship between exposure to environmental pollutants and early kidney damage biomarkers.

METHODS

A cross-sectional pilot study was conducted in February 2016 and involved 115 apparently healthy children aged 6-15 residing in Apizaco, Tlaxcala. Participant selection was carried out randomly from among 16,472 children from the municipality of Apizaco. A socio-demographic questionnaire included  age, sex, education, duration of residence in the area, occupation, water consumption and dietary habits, pathological history, and some non-specific symptoms. Physical examination included blood pressure, weight, and height. The urine concentrations of urinary aluminum, total arsenic, boron, calcium, chromium, copper, mercury, potassium, sodium, magnesium, manganese, molybdenum, lead, selenium, silicon, thallium, vanadium, uranium, and zinc, were measured. Four of the 115 participants selected for the study were excluded due to an incomplete questionnaire or lack of a medical examination, leaving a final sample population of 111 participants.

RESULTS

The results showed a mean estimated glomerular filtration rate of 89.1 ± 9.98 mL/min/1.73m2 and a mean albumin/creatinine ratio of 12.9 ± 16.7 mg/g urinary creatinine. We observed a positive and significant correlation between estimated glomerular filtration rate with fluoride, total arsenic and lead, and a correlation of albumin/creatinine ratio with fluoride, vanadium, and total arsenic. There was also a significant correlation between the early kidney damage biomarkers and fluoride, vanadium, and total arsenic, except for cystatin C.

CONCLUSION

In conclusion, our results show that four urinary biomarkers: α1-microglobulin, cystatin C, kidney injury molecule 1, and neutrophil gelatinase-associated lipocalin are related to environmental exposure to urinary fluoride, vanadium, and total arsenic in our pediatric population.

Neurotoxicidad en trabajadores petroquímicos con bajos índices de exposición a disolventes orgánicos

Objetivo. Estimar el desempeño neuropsicológico y su asociación con la exposición a disolventes orgánicos (DO) en trabajadores petroquímicos en México. Material y méto­dos. Estudio transversal en 203 trabajadores: 102 expuestos a DO y 101 no expuestos. Se evaluó el desempeño neuropsi­cológico con Neurobehavioral Core Test Battery y la exposición a DO con la medición de metabolitos de exposición para tolueno, xilenos y benceno. Resultados. Los trabajadores expuestos presentaron un peor desempeño en todas las pruebas (p<0.05), excepto en la prueba de Santa Ana. Esto se corroboró con modelos de regresión; los trabajadores expuestos a DO tuvieron un mayor número de errores y realizaron las pruebas en mayor tiempo (p<0.05), además de presentar mayores probabilidades de padecer síntomas de neurotoxicidad (OR: 2.93; IC95%: 0.96, 8.96). Conclusio­nes. La exposición ocupacional a disolventes orgánicos, aun a niveles permitidos por la normatividad mexicana vigente, se relacionó con un menor desempeño neuropsicológico.

Association between lead source exposure and blood lead levels in some lead manufacturing countries: A systematic review and meta-analysis

Lead is one of the 10 most toxic chemicals of greatest concern for its effects on public health. Predominantly, in undeveloped countries, high blood lead levels (BLLs) persist in the population. To develop intervention strategies that may reduce lead exposure in populations, it is a priority to know the sources of lead pollution. The objective of this critical review and meta-analysis is to assess whether there is an association between different sources of lead exposure and the mean difference in blood lead levels in people exposed. To identify the major lead source exposure, a statistical analysis was performed on selection studies. This investigation reveals the limited information available on the sources of lead in Mexico and other lead producer countries, such as Croatia, Ecuador, Brazil, South Korea, India, Nigeria, Turkey, and China. Meta-analysis could be performed only in battery, smelting mining, and glazed ceramic workers. Battery manufacturing workers have the highest mean difference level of lead in their blood worldwide. Mexico has the second highest mean difference BLL in battery workers in the world. An interesting difference between the mean difference in BLL in mining workers from uncontrolled industry (-39.38) and controlled industry (-5.68) was found. This difference highlighted the success of applying strict control of lead sources and community education to reduce BLL and its potential harmful effects on human health and the environment. Children living near mining sites have the highest mean difference BLL (-11.1). This analysis may aid in assessing the source of lead exposure associated with a range of BLLs in people. Furthermore, this review highlights several social and cultural patterns associated with lead exposure and lead levels in control populations. These results could help to develop international lead regulations and appropriate public health guidelines to protect people around the world.

Audiometric findings of printing press workers exposed to noise and organic solvents

OBJECTIVE

To determine if exposure to organic solvents and noise is associated with audiometric results among workers from a printing press in Mexico City.

DESIGN

Cross-sectional study.

STUDY SAMPLE

One hundred and seventy-six male workers at a printing press in Mexico City exposed to noise and organic solvents, including xylene, and 103 non-exposed male workers as reference group. Hearing thresholds were assessed with pure-tone audiometry.

RESULTS

Poorer hearing thresholds were observed among printing workers than non-exposed controls, particularly among groups with over 5 years of exposure. Hearing thresholds differences were observed in the frequencies above 500 Hz, especially in 4000 Hz in all exposure groups compared to the reference. Adjusted models for age and previous exposure to noise and organic solvents showed worse hearing thresholds as years of seniority increased -β coefficients (95% CI): ≤5 years: 3.06 dB (0.01, 6.10); >5-10 years: 4.51 dB (1.13, 7.89); >10 years: 4.58 dB (1.20, 7.96). Further analyses showed no interaction between noise and organic solvents on hearing thresholds, considering both current and previous occupational exposures.

CONCLUSION

Exposure to noise levels that were below recommended exposure limits and organic solvents were associated with poorer hearing thresholds than those observed among non-exposed study participants. This suggests that workers exposed to solvents should be included in hearing conservation programmes, even when noise exposures are below 85 dB. If only noise levels were taken into consideration in the risk assessment of this worker population, the risk of hearing effects could have been overlooked.

Neuropsychological effects among workers exposed to organic solvents

OBJECTIVE

To assess neuropsychological performance among workers at a paint factory in Mexico City.

MATERIALS AND METHODS

During 2004 and 2005 we assessed the neuropsychological performance of 208 workers who were exposed to organic solvents at a paint factory, mainly toluene and xylene. We categorized workers into low and high exposure groups using a cumulative index for toluene, based on times spent in different tasks. We evaluated cognitive and motor functions with 13 neuropsychological tests.

RESULTS

We found lower attention, longer time to complete the test β=5.5 (R2=12.3%), and a lower score in the motor-cognitive test β=-15.7 (R2=19.5%) in the high exposure group through multiple linear regression model analysis, with adjustment for age and education.

CONCLUSIONS

Our results are similar to the ones reported in the literature, but the effects are less severe, probably due to lower exposure to organic solvents.

[Determination of reference ranges for coagulation tests in Mexican-mestizo population]

BACKGROUND

It is necessary to establish biological parameters for each population.

OBJECTIVE

To establish reference values for prothrombin time (PT), activated partial thromboplastin time (PTT) and fibrinogen in healthy population and to determine intra- and inter-assay concordance.

METHODS

Cross-sectional study that included 204 women and 202 men from the Blood Donor service. Coagulation tests were carried out in order to obtain reference ranges. All procedures were made according to the Clinical & Laboratory Standards Institute guidelines.

RESULTS

Mean PT, PTT and fibrinogen were 14.1 s, 28.8 s and 381 mg/dL in men, and 15.1 s, 29.0 s and 381 mg/dL in women. The proposed PT, PTT and fibrinogen reference ranges for men were 12.7 to 16.3 s, 24.2 to 36.3 s and 239 to 276 mg/dL, respectively; for women, 12.7 to 16.6 s, 23.5 to 35.4 s and 276 to 598 mg/dL. The latter was statistically significant (p ≤ 0.001).

CONCLUSIONS

Reference values for blood coagulation tests were determined. This is of great importance for fast medical diagnosis and treatment. The results from this study can be adopted by other clinic laboratories after appropriate validation procedures.

Biomarkers for Predicting Malignant Pleural Mesothelioma in a Mexican Population

Background: Diagnosis of malignant pleural mesothelioma (MPM) remains a challenge, especially when resources in pathology are limited. The study aimed to evaluate cost-effective tumor markers to predict the probability of MPM in plasma samples in order to accelerate the diagnostic workup of the tissue of potential cases. Methods: We conducted a case-control study stratified by gender, which included 75 incident cases with MPM from three Mexican hospitals and 240 controls frequency-matched by age and year of blood drawing. Plasma samples were obtained to determine mesothelin, calretinin, and thrombomodulin using enzyme-linked immunosorbent assays (ELISAs). We estimated the performance of the markers based on the area under the curve (AUC) and predicted the probability of an MPM diagnosis of a potential case based on the marker concentrations. Results: Mesothelin and calretinin, but not thrombomodulin were significant predictors of a diagnosis of MPM with AUCs of 0.90 (95% CI: 0.85-0.95), 0.88 (95% CI: 0.82-0.94), and 0.51 (95% CI: 0.41-0.61) in males, respectively. For MPM diagnosis in men we estimated a true positive rate of 0.79 and a false positive rate of 0.11 for mesothelin. The corresponding figures for calretinin were 0.81 and 0.18, and for both markers combined 0.84 and 0.11, respectively. Conclusions: We developed prediction models based on plasma concentrations of mesothelin and calretinin to estimate the probability of an MPM diagnosis. Both markers showed a good performance and could be used to accelerate the diagnostic workup of tissue samples in Mexico.

[Chronic kidney disease in Mexico and its relation with heavy metals]

Chronic kidney disease (CKD) is a public health problem in Mexico, causing 25% of deaths related to diabetes mellitus (DM) and 28% related to hypertensive heart disease. In 2008 CKD reached the highest incidence of end-stage renal disease in the world. Diabetes mellitus is the main risk factor associated with CKD in Mexican population; however, heavy metals such as lead, arsenic, cadmium and mercury have been associated to nephropathies. In Mexico there are still high levels of these compounds in occupational and environmental settings; therefore, chronic exposures to these metals persist. In this review we approach to the main mechanisms of action of these metals in the body and its renal effects, as well as information about the sources of exposure to these chemical risks, the relationship between exposure to heavy metals and CKD, coupled with the economic and social consequences of this disease.

[Intelligence quotient loss in Mexican pottery artisan's children]

BACKGROUND

In Mexico, artisans frequently use lead oxide or greta in order to produce utensils, which are destined to preparation and storage of food and drinks. Additionally, the risk of lead poisoning of artisans and their families is greater than in general population, and within these families, children are the most susceptible to lead poisoning. The aim of this study was to estimate IQ loss in Mexican children from potter families exposed to lead.

METHODS

Lead concentrations in soil were determined in 19 potter's homes that functioned as pottery workshops in seven Mexican states between 2009 and 2012. This information was used to estimate blood lead levels through the integrated exposure uptake biokinetic (IEUBK) model. The loss of IQ points was then estimated according to the Lanphear and Schwartz models.

RESULTS

The mean lead concentration found in the workshops' soil was 1098.4 ppm. Blood lead levels estimated in children under 8 years old were 26.4 µg/dL and the loss of IQ points comprised from 7.13 to 8.84 points depending on the model.

CONCLUSIONS

It is possible that 11 children from families of artisans in Mexico may be losing between 7.13 to 8.84 IQ points, due to lead exposure in their houses-workshops. This loss in IQ points could have important health, economic and social impacts.

Blood lead determinants and the prevalence of neuropsychiatric symptoms in firearm users in Mexico

OBJECTIVES

To identify blood lead predictors and the prevalence of neuropsychiatric symptoms in firearm users of public security in Mexico.

MATERIAL AND METHODS

A cross-sectional study was performed on 65 males. We obtained socio-occupational data and determined venous blood lead (blood (B), lead (Pb) - BPb), as well as neuropsychiatric symptoms using the Q-16 questionnaire. A multiple linear regression model was constructed to assess determinants of BPb.

RESULTS

The mean age in the study group was 34.8 years (standard deviation (SD) = 6.9, range: 21-60); the mean number of years spent in the company amounted to 14 years (SD = 8.5, range: 1-48). Twenty percent of the respondents (N = 13) used leaded glazed clay pottery (lead (Pb), glazed (G), and clay pottery (C) - PbGC) in the kitchen. During practice they fired a mean of 72 shots (SD = 60, range: 20-250), and during their whole duration of employment 5483 shots (SD = 8322.5, range: 200-50 000). The mean BPb was 7.6 μg/dl (SD = 6.8, range: 2.7-51.7). Two caretakers from the firing range had 29.6 μg/dl and 51.7 μg/dl BPb. The subjects who had shooting practice sessions ≥ 12 times a year reported a greater percentage of miscarriages in their partners (24% vs. 0%). Twelve percent of the respondents showed an increase in neuropsychiatric symptoms. The BPb multiple linear regression model explained R2 = 44.15%, as follows: those who had ≥ 12 practice sessions per year - β = 0.5339 and those who used PbGC - β = 0.3651.

CONCLUSIONS

Using firearms and PbGC contributes to the increased BPb in the studied personnel. The determinants of BPb were: shooting practices >12 times a year and using PbGC. Blood lead concentrations reported in the study, despite being low, are a health risk, as evidenced by the prevalence of neuropsychiatric symptoms.

[Update on epidemiology, pathophysiology, diagnosis and treatment of malignant pleural mesothelioma]

Malignant pleural mesothelioma is an occupational tumor caused by asbestos exposure. In Mexico, as asbestos usage is not prohibited, an increase in the number of cases is expected. Asbestos exposure is ubiquitous due to the great amount of products in which it is present. Its carcinogenicity is caused as the inhaled asbestos fibers cannot be eliminated by macrophages and, thus, they travel to the pleura through lymphatic pathways, producing a persistent inflammatory response. Diagnosis approach includes occupational history, along with clinical signs and symptoms, and paraclinical studies, such as pleural fluid cytology, chest x-rays, computed tomography, magnetic resonance imaging, and biopsy with immunohistochemistry. The main differential diagnosis is lung adenocarcinoma. Regarding the treatment of this tumor, it mainly comprises palliative care, even though chemotherapy, radiotherapy, and, in selected cases, surgical treatments have been used. There is an urgent need for general physicians and specialists to identify asbestos exposure, in order to make a timely diagnosis. Research is necessary to develop screening and prompt diagnostic tools, along with an epidemiological surveillance program for the workers and the general population exposed to asbestos.

[Brainstem auditory evoked potentials latencies, by age and sex, among Mexican adult population]

BACKGROUND

Brainstem auditory evoked potentials (BAEP) evaluate the auditory pathway, and are a complementary test for tone audiometry in evaluating auditory diseases. The aim of the study was to determine BAEP mean latencies of waves and intervals, among healthy adults.

METHODS

Cross-sectional study, comprising 196 subjects, aged 16 to 65 years, without auditory diseases, to whom family and personal history were asked, physical examination and laboratory studies were made, as well as tonal audiometry, impedanciometry and BAEP.

RESULTS

A total of 107 men and 89 women were studied. The mean latency periods of waves I, III and V, and intervals I-III, III-V and I-V from both ears were similar. An increase in the latency periods for each age category was observed. Latency periods were significantly shorter in women compared to men. The predictors that increased the latency periods in the multiple linear regression models for waves and intervals were male gender and age ≥45 years.

CONCLUSIONS

Age and sex were the variables that showed more statistical power to explain the latencies' differences.

[Historical and social perspective from the 64-65 Mexican medical movement]

The Mexican Medical Movement from 1964-1965 constitutes an important event from the rising urban middle-class, besides it was the first time medical doctors claimed for fair working conditions. The background of this movement is the so-called Crisis of 1958, which included the Movements from the educators union, oil workers union, telegraph workers union and the railroad workers union. The conflict began because interns and residents from the "Hospital 20 de Noviembre" would not get a payment at the end of the year, so on November 26th, 1964, the movement started. The Asociación Mexicana de Médicos Residentes e Internos (AMMRI) was created and their demands were the following: 1) Full working site restitution without retaliations, 2) Legal examination of the scholarship-contract terms, in order to get annual, renewable and progressive contracts, and a fixed salary with the usual working-hours and characteristics of each institution, 3) To have preference to get an adscription at the hospital where the resident studied, 4) Active participation from the resident in the elaboration of the academic plans, and 5) Resolution of each hospital's problems. This movement had social impact for Mexico's contemporary life, nevertheless some of the demands are still unchanged among medical residents.

[Overview of sharps injuries among health-care workers]

Sharps injuries are one of the most frequent health-care related accidents. It is estimated globally that 35 million workers are at risk; in Mexico there is no data available for this type of injuries. They are associated with lack of training, instrument and procedure risk, fatigue and stress. The occupational distribution is nurses 45 %, technicians 20 %, doctors 20 % and maintenance workers 5 %. The most commonly associated procedures are injection, venipuncture, suture, and insertion and manipulation of IV catheters. Hepatitis B is the most commonly transmitted agent. Emotional distress is huge as well as the cost of prophylaxis and follow-up. More than half of the injuries are not notified. The most common reasons for not reporting are: the belief that the exposure has low risk of infection, the lack of knowledge of reporting systems and the assumption that it is difficult to notify. Many strategies have been created to reduce the incidence of sharps injuries, such as: identifying the risk of blood exposure, the creation of politics to minimize the risk, the education and training to create a safe workplace, the enhancing of the reporting system, the use of double-gloving and using safety-engineered sharps devices. In many countries these politics have reduced the incidence of sharps injuries as well as the economic burden.

Seroprevalence of Pandemic A(H1N1) pmd09 Virus Antibodies in Mexican Health Care Workers Before and After Vaccination

BACKGROUND AND AIMS

In April 2009, a new strain of influenza A(H1N1) was identified in Mexico and in the U.S. In June 2009, WHO declared this a pandemic. Health care workers constituted a risk group for their close contact with infected individuals. The aim was to estimate seropositivity for A(H1N1)pdm09 in health staff at the Instituto Mexicano del Seguro Social.

METHODS

A two-stage cross-sectional study, before and after vaccination in the same workers, was performed on a random sample of health-care workers. A socio-occupational questionnaire was applied and serum antibodies against influenza A(H1N1)pdm09 were determined through neutralization of retroviral pseudotypes; two logistic regression models for both were constructed.

RESULTS

The average (median/mean) age of 1378 participants from 13 work centers was 41.7 years and 68.7% (947) were women. Seroprevalence for the first stage was 26.5% (365) (7.4-43%) vs. 20.8% (11) in a control group from the blood bank; for the second stage, the vaccinated group was 33% (215) (18.2-47%) and 27% (196) (11.6-50%) for the unvaccinated group. In regression models, seropositivity was associated with occupational exposure to suspected influenza infected patients, being physicians, and being vaccinated.

CONCLUSIONS

Seropositivity against pandemic virus is similar to what was reported, both for vaccinated (2.8-40.9%) and unvaccinated (18.8-64.7%). Low seroprevalence in the vaccinated group indicates that between 67% and 73% were susceptible to infection. Given the relatively low vaccine-induced seropositivity, it is imperative to increase, hygiene and safety for health staff and at-risk populations, and strengthen epidemiological surveillance.

Malignant Pleural Mesothelioma: Accuracy of CT Against Immunohistochemical Test Among the Mexican Population

BACKGROUND AND AIMS

Malignant pleural mesothelioma (MPM) is associated with occupational and environmental exposure to asbestos. The incidence is expected to increase as the use of asbestos is not prohibited in many countries, such as in Mexico. We undertook this study to determine sensitivity, specificity, predictive values and likelihood ratios of computed tomography (CT) in a sample from Mexican population with suspected MPM and other pleuropulmonary diseases.

METHODS

CT films of 38 patients suspected of having MPM were analyzed. A single observer was blinded to MPM diagnoses. The frequencies of ten CT findings were identified. A cut-off point of ≥5 CT findings was established to determine high MPM probability. Sensitivity, specificity, predictive values and likelihood ratio of the CT against biopsy using immunohistochemical testing (IHC) for MPM were calculated.

RESULTS

Of the 38 patients, 31 had MPM and seven had lung adenocarcinoma. The five key findings were mediastinal pleural thickening 96.7% (n = 30), nodular pleural thickening 93.3% (n = 29), pleural mass 83.9% (n = 26), diminished lung 70.9% (n = 22) and contracted hemithorax 70.9% (n = 22). Sensitivity 96.8% (83.2-99.4), specificity 85.7% (42.2-97.6), positive likelihood ratio 6.7 (1.1-41.6), and negative likelihood ratio of 0.04 (0.01-0.2) were reported.

CONCLUSIONS

Sensitivity and specificity in this study was greater than previously reported, 96.8% and 85.7 vs. 93.2 and 65.6%, respectively. CT is an easily accessible and useful tool that should be incorporated into the medical education of general physicians to improve MPM diagnosis of suspected cases.

[Concordance in blood lead quantification between laboratories]

OBJECTIVE

To establish a blood lead quantification correlation from two occupational health laboratories (OHL1V and OHL2DF), and the ABC Hospital (LABC) metals laboratory.

METHODS

A cross-sectional study was performed in 84 workers from a voltage regulators company, where lead is welded; in 54 % (46 of them) a blood sample was taken and analyzed by OHL1V, and in 28.6 % (24) by OHL2DF. All samples were analyzed by atomic absorption spectrophotometry. Pearson correlation (r), coefficient of determination (r2), Lin (rho) concordance test, and Bland-Altman plots were calculated.

RESULTS

The blood lead mean: LABC was 5.8 ± 2.4 μg/dL vs. OHL2DF of 4.4 ± 3.6 μg/dL (r = 0.25 [p = 0.24], r2 = 0.06 [p = 0.24], and rho = 0.21 [p = 0.21]). And with LABC, 6.75 ± 3.3 μg/dL vs. OHL1V 5.6 ± 2.9 μg/dL (r = 0.91 [p < 0.001], r2 = 0.83 [p < 0001], and rho = 0.85 [p< 0.001]).

CONCLUSIONS

Agreement between LABC and OHL1V was poor (< 0.90), and with OHL2DF was null. An occupational health laboratory certification is needed in order to have reliable biological exposure index measurements in lead occupational exposure.

[Male hormonal profile in workers exposed to toluene in an industrial packaging plant]

OBJECTIVE

to identify changes in the male hormonal profile (MHP), consisting of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone, in workers exposed to toluene.

METHODS

cross-sectional study that included 42 workers, formed in two groups: with high and low exposure to toluene (HET and LET, respectively); the hippuric acid in urine, and the serum concentration in FSH, LH, and testosterone were measured.

RESULTS

hippuric acid in subjects with LET was 2.53 ± 1.20 g/g creatinine, and with HET: 6.31 ± 3.83 g/g creatinine (p = 0.02). Seric FSH concentration was 5.12 ± 0.77 and 3.55 ± 0.3 mU/mL (p = 0.02) in LET and HET, respectively; LH: 2.66 ± 0.45 and 2.77 ± 0.21 (p = 0.81), and testosterone 3.91 ± 0.34 and 4.86 ± 0.23 ng/mL (p = 0.04). By regression analysis, the correlation coefficient of FSH with hippuric acid was r = -0.33 (p = 0.031), with coefficient of determination of 11 %; the LH correlation coefficient was r = -0.037 (p = 0.88) and 0.05 %, respectively; and the one for testosterone was r = 0.61 (p = 0.0001) and 34 %.

CONCLUSIONS

in HET group, FSH and LH serum levels diminished; testosterone shows an opposite response, perhaps explained by a different sensitivity of the male gonads exposed to toluene.

Are Mexican agricultural farmlands PCDD/F soil reservoirs?

Our aim was to identify polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-p-furans (PCDFs) in agricultural farmland soils in the Northwest of Mexico. We obtained ≈50 g of soil in five Yaqui Valley (VY) agricultural fields in the north-western Mexican State of Sonora and in five Culiacán Valley (VC) agricultural fields in the north-western Mexican State of Sinaloa. Fields with minimal tillage, with ferti-irrigation, and those with intensive aerial and manual tillage were included. All soil samples were subjected to the chemical activated luciferase gene expression (CALUX(®)) test to determine PCDD/F. On average, samples contained 4.2 ± 1.2 PCDD/F ppt TEQ; VY soil samples contained 4.72 ± 1.23 PCDD/F ppt TEQ, while VC soil samples showed 3.6 ± 1.1 PCDD/F ppt TEQ (p = 0.47). On considering tillage-type, in agricultural fields catalogued as intensive tillage, PCDD/F concentrations were 4.40 ± 0.43 in agricultural fields catalogued as intensive tillage, while in farmlands of another tillage-type these concentrations were slightly higher (5.53 ± 0.8).

[Estimation of health-care costs for cervical uterine neoplasm]

OBJECTIVE

to value diagnostic stage and direct costs due to cervical cancer in insured workers and IMSS beneficiaries patients, during first year of treatment.

METHODS

80 records of patients with confirmed diagnosis of cervical cancer during 2000-2003 were analyzed. The study was made under provider public health services perspective, with focus in costs incidence during 2009.

RESULTS

27 (34 %) of total records corresponding to insured worker and 53 (66 %) to beneficiaries. No differences were finding in diagnostic stage. In bout groups stage II was the most common. The cost due medical care adds up to $91,064.00 during first year of treatment in workers. The main costs were identified in sickness absence certification (31 %), image exams (24 %) consulting room (19 %), radiotherapy sessions (10 %) and hospitalization (9 %).

CONCLUSIONS

cervical cancer is a frequent disease that affects women in their productive and reproductive age. Frequently their diagnosis is made in advanced stages, which increase medical attention cost. It is convenient to introduce more effective preventive actions, including the workplace.

Case-control study of pleural mesothelioma in workers with social security in Mexico

BACKGROUND

Environmental and occupational exposure to asbestos in Mexico in the past has been a cause of deaths and health damages. Its magnitude is unknown to date. Our objective was to identify the proportion of cases of malignant pleural mesothelioma (MPM) that can be attributed to and occupational exposure to asbestos.

METHODS

We carried out a case-control study of MPM in 472 workers insured by the Mexican Institute of Social Security, all Valley of Mexico residents, with 119 incident cases and 353 controls. Cases were histologically confirmed. Participants were questioned concerning their occupational history and sociodemographic data. Assignment to one of the four exposures was performed qualitatively by an expert hygienist. Odds ratios (ORs) and attributable risks (ARs) were calculated using a non-conditional logistic regression model.

RESULTS

A total of 80.6% of cases and 31.5% of controls had occupational exposure to asbestos. ORs were adjusted for age and gender and by exposure category, and exhibited an increase with probability of exposure as follows: 3.7(95% CI 1.3-10.4) for the likely category and 14.3(95% CI 8-26) for the certain category; AR in the group occupationally exposed to asbestos was 83.2%, and the population AR was 44%.

CONCLUSIONS

Our results show that the relationship between industrial uses of all forms of asbestos is generating an increase in mesothelioma-related diseases and deaths among Mexican workers. As a public health policy, Mexico should prohibit the use of asbestos in all production processes with the aim of controlling the epidemic and preventing the occurrence of new cases of MPM.

[Clinical aptitude in occupational medicine residents]

OBJECTIVE

To determine clinical aptitude (AC) in occupational medicine residents.

METHODS

An instrument based on real clinical cases was built and validated to assess AC, which was composed by surveillance indicators of the workers health (SIWH) and occupational-medical evaluation indicators (0ME) In the study participated 22 undergraduate students (UE), 40 residents of first year (R1) and 36 of second year (R2). The instrument was validated by experts.

RESULTS

Internal consistency of the instrument was 0.93 by Kuder-Richardson. Regarding global AC, 96 % of UE were situated in a random level and 4 % in a very low level. 15 % of R1 was situated in a random level, 50 % in a very low level, 30 % low level and 5 % in medium level; whereas R2 3 % was positioned in a random level, 28 % in a very low level, 50 % in low level and 19 % in medium level. A significant difference was found between R1 and R2 in occupational-medical evaluation (p < 0.009), but not in SIWH. Two centers showed statistical difference in both indicators.

[Occupational exposure-associated hematological and immunologic manifestations to the benzene-toluene-xylene (Btx) mixture]

Despite, the idea promoted to study occupational exposure to benzene and its mixture with toluene and xylene (BTX) because it appears to determine its toxicity and probably the production of additive effects, it persists interest to recognizing its hematological and immunotoxic effects. The fact that exposure to a sole substance in the occupational field is infrequent. Available contributions that analyze these implications are scarce, with contradictory results, and in their majority are limited to the fraction of benzene. Epidemiologic studies that have evaluated occupational exposure to any of the BTX fractions have been based on personal monitoring, while others have characterized this heterogeneously and are accompanied by weaker proposals. The conformation of specific methods to stimulate occupational exposure to the BTX mixture would contribute to its homogenization and allow for a more integral view in terms of determining BTX exposure. On the other hand, the application of BTX exposure biomarkers has been questioned in studies contemplating the specific biological effects of reference-associated chronic exposure. Analysis of the hematological and immunologic manifestations associated BTX mixture is based on information that is unclear, controversial, or even speculative to date.

Burnout and patient care in junior doctors in Mexico City

BACKGROUND

Burnout is known to occur in public service workers leading to a reduction in effectiveness at work.

AIM

To estimate the prevalence of burnout in junior doctors and its impact on patient care.

METHODS

A cross-sectional study of junior doctors at three hospitals in Mexico City was conducted. Measures used included the Maslach Burnout Inventory (MBI), measuring depersonalization (DP), emotional exhaustion (EE) and personal achievement (PA), a questionnaire about patient care practices and attitudes and one on sociodemographic characteristics. Logistic regression analysis was used to assess the association between burnout and suspected risk factors.

RESULTS

A total of 312 junior doctors participated (response rate 65%). In total, 57% were male and the average age was 28. Average scores in MBI subscales were EE: 18.2, DP: 6.9 and PA: 37.6. Burnout prevalence was 40% (126). Junior doctors with burnout were more likely to report suboptimal patient care practices occurring monthly (OR 5.5; 95% CI 2.7-11.2) and weekly (OR 5.2; 95% CI 1.6-16.3). The logistic regression model for burnout included shifts lasting >12 h, current depression, former major depression, first- or second-year junior doctors, male gender and single status.

CONCLUSIONS

Burnout was most strongly associated with shifts >12 h and with both current and previous depression. Reported suboptimal patient care was also associated with working shifts of >or=12 h. Burnout may be adversely affecting junior doctors' health and their patients' care.

[Symptom prevalence and pesticide management on agricultural workers]

INTRODUCTION

Mexico is a main importers of pesticides in Latin America.

OBJECTIVE

to describe pesticide symptoms prevalence, use, and management in a group of agricultural workers.

METHODS

we carried out a transversal study in 303 agricultural workers laboring in vegetables, grains and flowers fields. We investigated the work history, pesticide management, and pesticide use frequency, as well as exposure-associated symptoms.

RESULTS

mean age was 46 years; 19.5 % of workers were illiterate, and mean pesticide use was 15 years. With regard to pesticide application, 17.2 % of laborers worked with pesticides from 11:00 a. m. to 3:00 p. m., and 36.4 % of them applied pesticides for > 2 h; 29.7 % applied pesticides against the wind, while 26.4 % applied these with the wind. After applying the pesticides, 37.4 % of them bathed after 3 h, 34.5 % changed clothes, and 18.8 % returned to cultivation some hours later; 23 % of workers presented some symptom, the most frequent being headache, itchiness, numbness, and perception of burning on skin; this latter proportion was greater in the < or = 46 years old group

CONCLUSIONS

symptom prevalence is in agreement with inappropriate pesticide management; nonetheless, we found no statistically significant association. Our results are lower than other studies, possibly due to lesser exposure, determined by toxicity, pesticide amount utilized, and use and management of chemicals.

[Reliability and validity of a generic job exposure matrix applied on a small-business]

OBJECTIVE

to evaluate the reliability and validity of a generic job exposure matrix (JEM) applied in a small business.

METHODOLOGY

procedures to evaluate a JEM integrated by six sections: the number of exposed workers per area, frequency of exposure, time of exposure time, level of exposure, safety controls, and proximity to source of exposure, was evaluated. The JEM also obtains information about possible health effects from exposure to occupational/environment agents. Two observers estimated the risk of exposure to epoxy resins on 31 workers of an epoxy resin facility in Mexico City. The rater agreements between the two observers were assessed through percent agreement (PA), weighted kappa (kappa(w)) and the intraclass correlation coefficient (ICC).

RESULTS

disagreements were greater for the number of exposed workers (PA = 61.3, kappa(w) = 0.24, ICC = 0.33), level of exposure (PA= 66.7, kappa(w) = 0.25, ICC= 0.56), and safety controls (PA = 54.8, kappa(w) = 0.23, ICC = 0.69) sections. Percent agreement and kappa(w) were 64% and 0.58, respectively. In accordance with Landis and Koch, Altman, Fleiss, and Byrt classifications for the interpretation of kappa value, the weighted kappa (0.58) ranged from moderate to a fair good level.

CONCLUSIONS

despite the discordance in some sections, the JEM proved to be useful to identify the risk of exposure in this type of small business.

[Medical justification of the eight-hour shift work]

The 8-hour shift work is one of the main achievements of the organized workers. International solidarity with United States miners, who were massacred in Chicago in 1886, and the aftermath of World War I promoted the establishment of 8-hour shift work in many countries. In Mexico, the 1917 Social Rights Declaration adhered to this position under the idea that the excessive workload above the 8-hour limit had negative effects on the health of workers; nevertheless, this statement seems to be sustained only by testimonies, anecdotal opinions and/or by the logic and common sense that then prevailed. For this reason, a literature review was carried out in search for the evidence supporting this apparently immovable length of the shift work. The globalization of the economy and the tendency towards flexibility and deregulation of current contractual relationships, are the new challenges that the 8-hour shift work is facing.

Occupational health in Mexico

This article describes the current situation of occupational health (OH) in Mexico, including socioeconomic context, legislation, health system, and educative and investigative resources, as well as the practice of OH. Workplace accidents per 100 workers decreased from 7.23 to 2.3 workers in 20 years; deaths decreased from 1.68 to 0.9 per 10,000 workers, while the occupational disease rate increased from 0.6 to 1 per 10,000 workers. This can be interpreted as an improvement in preventive measures as well as problems of recognition and registry. In Mexico OH faces challenges that range from needs for professional training and performance to needs for development of legal measures, coordination, information, and research.

Predictors of plasma lead among lithographic print shop workers in Mexico City

BACKGROUND

Plasma lead is considered a biological marker that reflects the fraction of lead in blood that is toxicologically available. We examined the relationship between plasma lead and other biomarkers of lead exposure in 69 lithographic print shop workers.

METHODS

Lead was measured in plasma and whole blood (by inductively coupled plasma-magnetic sector mass spectrometry), in bone (by 109Cd X-ray fluorescence), and in hand wipes and occupational air samples. Personal hygiene habits at work were surveyed.

RESULTS

Mean age was 47 years and 86% (n=59) were men. Mean lead levels were 0.3 microg/L in plasma, 11.9 microg/dL in blood, 46.7 microg/g in patella, and 27.6 microg/g in tibia. Taken together, two multivariate linear models explained 57% of variability in plasma lead levels. Predictors for the first model were lead in patella (beta = 0.006), blood (beta = 0.008), and hygiene index (beta = -0.11). Predictors for the second model were lead in tibia (beta = 0.008), blood (beta = 0.008), and hygiene index (beta = -0.13).

CONCLUSIONS

This study demonstrates that accumulated bone stores and hygiene habits are both significant independent predictors of plasma lead levels in active workers at this print shop.

[Occupational exposure to inorganic lead in a printing plant in Mexico City]

OBJECTIVE

To describe occupational lead exposure and its biological indicators in workers in a printing company.

MATERIAL AND METHODS

An epidemiological and industrial hygiene research was undertaken. Lead was measured in the air of work environment and on the hands of the participants; additionally, subjects underwent a venous blood samples for the determination of whole blood lead by atomic absorption spectrophotometry; and a bone lead measurement using a spot-source 109Cd K-X-ray fluorescence instrument. Also, a standardized questionnaire was applied. We obtained information on demographic and life styles factors, work history, type of work, position and activity within the company.

RESULTS

Of the 209 workers, 117 agreed to participate and 90 (83.3% males and 16.7% females) completed all phases of the study. The average lead concentrations were: in air samples, of 0.94 microgram/m3; in hands before washing, of 6,802 micrograms/m2; in hands after washing, of 194 micrograms/m2; in whole blood, of 12.3 micrograms/dl; and in tibia and fibula, of 25.9 and 43.3 micrograms Pb/g of bone mineral, respectively. Important variations in these measurements were observed according to the workers post.

CONCLUSIONS

Worldwide, lead exposure levels have been used to evaluate acute exposures being in the workplace. The higher lead levels find in the bone of the workers in this study are similar to other occupational studies in the United States of America and suggest that the accumulated metal in bone may be an important endogenous exposure source, and here its measurement importance. However in developing countries because its high costs per application, the measurements in bone lead become limited to epidemiological research, although not as an instrument for occupational epidemiological surveillance. In Mexico, there are no reliable studies of occupational lead exposure, which would allow the establishment of both, maximum permissible ambient and biological levels. This study is intended to contribute to blood lead standard setting, which is being discussed in Mexico.