"I Do Not Have the Time of Being sick": Para-Occupational Exposure and Women's Health Risk Perception in an Agricultural Community.

INTRODUCTION: Few studies have explored the relationship between para-occupational exposure and risk perception in farmers' families. Women are indirectly involved in agricultural activities, even though their roles most of the time are hidden. Women's para-occupational exposure and risk perceptions are important to describe, since women have a key gender role in the family's health care and possibly in the impact of acting regarding pesticide safety education. Furthermore, in farmer families, the impact of para-occupational pesticide exposure on women's health has been neglected. AIM: Analyze pesticide para-occupational exposure scenario, knowledge, and health risk perception among women living in a farmer community. METHODS: A mixed methodology was used. Two groups of women were identified to screen the exposure scenario: Women living in a farming family and women not living in a farming family. Data on para-occupational pesticide exposure and intradomicile practices were collected by questionnaire and semi-structured interviews to identify health risk perception and risk practices. RESULTS: We observed a complex pesticide exposure scenario. All women were potentially exposed to pesticides through several pathways. One-third of the participants lived near a farming family or in proximity to neighbors that used pesticides at home, and one of every three women referred to spending time in a farmer's home. Among the group of women in a farming family (n = 18) stored pesticides inside the home was common; having the "safety practice" of storing pesticides in high places to avoid children being exposed. Women not living in farmimg families (n = 11) felt overexposed due to living in an agricultural community and agricultural drift exposure. Women from this group also mentioned feeling fear of developing cancerous diseases as well as fertility problems. CONCLUSIONS: Knowledge and risk perception of pesticide exposure are similar between groups; however, women living in farming families were less willing to attend preventive health check-ups or educational programs than women not living in a farming family.

Dosing of Cannabinoids Associated with an Opioid-Sparing Effect: A Systematic Review of Longitudinal Studies.

OBJECTIVE: To assess cannabinoid dosing that could be associated with a reduction in opioid use. DESIGN: Systematic review conducted according to the PRISMA statement. DATA SOURCES: PubMed, Embase, Web of Science, and PsycINFO were searched up to December 10, 2022. REVIEW/ANALYSIS METHODS: We included randomized controlled trials (RCT) and longitudinal observational studies assessing cannabinoids effect on opioid use in patients with acute or chronic pain. Two reviewers independently assessed the studies for inclusion and extracted the data. Tetrahydrocannabinol (THC), Cannabidiol (CBD), and other cannabinoids with dosing were the exposures. Change in opioid doses and opioid discontinuation were the outcomes. RESULTS: Fifteen studies (including seven RCTs) were included. Eight studies (six observational and two RCTs) were conducted among patients with chronic pain including three with cancer-related pain. Seven studies involved patients with acute pain (five RCTs).In chronic non-cancer pain patients, two observational studies that assessed THC and CBD in combination (average daily dose 17mg/15mg), and one that assessed a CBD-rich extract (31.4 mg/day), showed a significant reduction in opioid use. Of the three studies conducted on patients with cancer, only the observational study that assessed nabilone (average 1.7 mg/day) showed a significant reduction in opioid use. In patients with acute pain, only two observational studies that assessed dronabinol (5mg and 5-10 mg/day for four days) showed a significant reduction in opioid use. CONCLUSION: The opioid-sparing effect of cannabinoids remains uncertain based on current evidence. However, attention could be paid to cannabinoid doses associated with opioid reduction in included observational studies.

Association Between Enteral Supplementation With High-Dose Docosahexaenoic Acid and Risk of Bronchopulmonary Dysplasia in Preterm Infants: A Systematic Review and Meta-analysis.

Importance: High-dose docosahexaenoic acid (DHA), a long-chain polyunsaturated fatty acid, may affect the risk of bronchopulmonary dysplasia (BPD). However, high-level summative evidence supporting such clinical association in very preterm infants is lacking. Objective: To examine the association between enteral supplementation with high-dose DHA during the neonatal period and the risk of BPD in preterm infants born at less than 29 weeks' gestation. Data Sources: PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, medRxiv, and ClinicalTrials.gov were searched from inception to August 1, 2022, for eligible articles with no language restrictions. Study Selection: Randomized clinical trials (RCTs) were eligible for inclusion (1) if their interventions involved direct administration of a minimum DHA supplementation of 40 mg/kg/d or breast milk or formula feeding of at least 0.4% of total fatty acids, and (2) if they reported data on either BPD, death, BPD severity, or a combined outcome of BPD and death. Data Extraction and Synthesis: Two investigators completed independent review of titles and abstracts, full text screening, data extraction, and quality assessment using the Cochrane Risk of Bias 2.0. Risk ratios (RRs) with 95% CIs were pooled using random-effect meta-analyses. Main Outcomes and Measures: Primary outcome was BPD using trial-specific definitions, which was further stratified for RCTs that used a more stringent BPD definition based on systematic pulse oximetry assessment at 36 weeks' postmenstrual age. Other outcomes were BPD, death, BPD severity, or combined BPD and death. Results: Among the 2760 studies screened, 4 RCTs were included, which involved 2304 infants (1223 boys [53.1%]; mean [SD] gestational age, 26.5 [1.6] weeks). Enteral supplementation with high-dose DHA was associated with neither BPD (4 studies [n = 2186 infants]; RR, 1.07 [95% CI, 0.86-1.34]; P = .53; I2 = 72%) nor BPD or death (4 studies [n = 2299 infants]; RR, 1.04 [95% CI, 0.91-1.18]; P = .59; I2 = 61%). However, an inverse association with BPD was found in RCTs that used a more stringent BPD definition (2 studies [n = 1686 infants]; RR, 1.20 [95% CI, 1.01-1.42]; P = .04; I2 = 48%). Additionally, DHA was inversely associated with moderate-to-severe BPD (3 studies [n = 1892 infants]; RR, 1.16 [95% CI, 1.04-1.29]; P = .008; I2 = 0%). Conclusions and Relevance: Results of this study showed that enteral supplementation with high-dose DHA in the neonatal period was not associated overall with BPD, but an inverse association was found in the included RCTs that used a more stringent BPD definition. These findings suggest that high-dose DHA supplementation should not be recommended to prevent BPD in very preterm infants.

Health Risk Assessment in Children Occupationally and Para-Occupationally Exposed to Benzene Using a Reverse-Translation PBPK Model.

Benzene is a known human carcinogen and one of the ten chemicals of major public health concern identified by the World Health Organization. Our objective was to evaluate benzene's carcinogenic and non-carcinogenic health risks (current and projected) in highly exposed children in Yucatan, Mexico. Benzene exposure was estimated through a reverse-translation, four-compartment, physiologically based pharmacokinetic model (PBPK) based on previously performed urine trans, trans-muconic acid (benzene metabolite) determinations. Using a risk assessment methodology, the carcinogenic and non-carcinogenic risks of benzene were estimated for 6-12-year-old children from a family of shoemakers. The children's hazard quotients for decreased lymphocyte count were 27 and 53 for 4 and 8 h/day exposure, respectively, and 37 for the projected 8 h/day exposure in adults. The risks of developing leukemia were 2-6 cases in 1000 children exposed 4 h/day; 4-10 cases in 1000 children exposed 8 h/day, and 2-9 cases in 1000 adults with an 8 h/day lifetime exposure. Children in Yucatan working in shoe-manufacturing workshops, or living next to them, are exposed to benzene concentrations above the reference concentration and have unacceptably high risks of presenting with non-carcinogenic and carcinogenic hematologic symptoms, now and in the future. Interventions to prevent further exposure and mitigate health risks are necessary.

Conradi-Hünermann-Happle syndrome: Clinical and trichoscopic findings.

Conradi-Hünermann-Happle syndrome (CHHS) is a rare genodermatosis resulting from mutations in the EBP (emopamil binding protein) gene. Dermatologic manifestations may include cicatricial alopecia, ichthyosis, follicular atrophoderma, pigmentary abnormalities, and nail dystrophy. In addition to genetic testing and clinical findings, trichoscopic findings may aid in the diagnosis. In this case report, we discuss the trichoscopic findings in a 3-year-old girl with CHHS and how these findings help us understand the pathophysiology of this disease.

Agricultural pesticide residues in water from a karstic aquifer in Yucatan, Mexico, pose a risk to children's health.

Yucatan is a region with a high impact of water contamination since it has a karst type soil favoring contaminants entry into the phreatic level, the only source of freshwater in the area. However, no studies report pesticides in water for human consumption or the risk it represents. The objective of this study was to detect and measure pesticide concentrations in domestic tap water to estimate the risk (carcinogenic and non-carcinogenic) to health. A non-probabilistic sampling was applied of 48 tap water sources, and then pesticide detection with solid-phase extraction gas chromatography coupled to the electron capture and flame photometric detectors allowed the estimation of risk through hazard ratios. The present results suggest that aldrin, heptachlor, and ß-BHC residues in domestic tap water from Ticul, Yucatan, pose a risk to children's health, particularly for potential carcinogenic risks.

Scalp Rosacea: Rethinking Peripilar Scaling.

INTRODUCTION: Scalp rosacea is scarcely reported in the literature, but it is probably not uncommon. Trichoscopic findings have not been specifically established for this entity. CASE PRESENTATION: We report 4 cases of chronic scalp rosacea with trichoscopic evidence of peripilar scaling that resolved without scarring after treatment. DISCUSSION/CONCLUSION: Chronic and persistent inflammation around the isthmus produced in scalp rosacea may form peripilar scaling resembling that found in lichen planopilaris.

Evaluation of hydroxylated metabolites of polycyclic aromatic hydrocarbons and biomarkers of early kidney damage in indigenous children from Ticul, Yucatán, Mexico.

Polycyclic aromatic hydrocarbons (PAHs) are environmental persistent chemicals, produced by the incomplete combustion of solid fuels, found in smoke. PAHs are considered carcinogenic, teratogenic, and genotoxic. Children are susceptible to environmental pollutants, particularly those living in high-exposure settings. Therefore, the main objective of this study was to evaluate the exposure to PAHs through hydroxylated metabolites of PAHs (OH-PAHs), 1-hydroxynaphtalene (1-OH-NAP), and 2-hydroxynaphtalene (2-OH-NAP); 2-,3-, and 9-hydroxyfluorene (2-OH-FLU, 3-OH-FLU, 9-OH-FLU); 1-,2-,3-, and 4-hydroxyphenanthrene (1-OH-PHE, 2-OH-PHE, 3-OH-PHE, 4-OH-PHE); and 1-hydroxypyrene (1-OH-PYR), as well as kidney health through biomarkers of early kidney damage (osteopontin (OPN), neutrophil gelatinase-associated lipocalin (NGAL), α1-microglobulin (α1-MG), and cystatin C (Cys-C)) in children from an indigenous community dedicated to footwear manufacturing and pottery in Ticul, Yucatán, Mexico. The results show a high exposure to PAHs from the found concentrations of OH-PAHs in urine in 80.5% of the children in median concentrations of 18.4 (5.1-71.0) µg/L of total OH-PAHs, as well as concentrations of kidney damage proteins in 100% of the study population in concentrations of 4.8 (3-12.2) and 7.9 (6.5-13.7) µg/g creatinine of NGAL and Cys-C respectively, and 97.5% of the population with concentrations of OPN and α1-MG at mean concentrations of 207.3 (119.8-399.8) and 92.2 (68.5-165.5) µg/g creatinine. The information provided should be considered and addressed by the health authorities to establish continuous biomonitoring and programs to reduce para-occupational exposure in the vulnerable population, particularly children, based on their fundamental human right to health.

Association of Trichorhinophalangeal Syndrome and Loose Anagen Syndrome: A Case Report.

Trichorhinophalangeal syndrome (TRPS) is an autosomal dominant disease characterized by trichologic, craniofacial, and musculoskeletal abnormalities. Predominant clinical features include a pear-shaped nose with bulbous tip, long philtrum, protruding ears, and sparse hair on both the scalp and the lateral third of the eyebrows. Cone-shaped epiphyses are a common radiographic finding. Loose anagen syndrome (LAS) is a sporadic or autosomal dominant condition due to abnormalities in the hair's anchoring mechanism. It mostly affects children, who usually have reduced hair length, as well as hair that is easily plucked without pain. Recent contributions regarding trichoscopic findings of LAS have been made, describing rectangular black granular structures as a typical feature. An association between TRPS and LAS has been mentioned by hair experts, but no reports documenting this have been published. This case demonstrates the co-existence of both conditions in a patient with characteristic phenotypic traits of TRPS and LAS.

Different gene expression profiles in subcutaneous & visceral adipose tissues from Mexican patients with obesity.

Background & objectives: Obesity is a health problem that requires substantial efforts to understand the physiopathology of its various types and to determine therapeutic strategies for its treatment. The objective of this study was to characterize differences in the global gene expression profiles of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) between control patients (normal weight) and patients with obesity (IMC≥30) using microarrays. Methods: Employing RNA isolated from SAT and VAT samples obtained from eight control and eight class I, II and III patients with obesity, the gene expression profiles were compared between SAT and VAT using microarrays and the findings were validated via real-time quantitative polymerase chain reaction. Results: A total of 327 and 488 genes were found to be differentially expressed in SAT and VAT, respectively (P≤0.05). Upregulation of PPAP2C, CYP4A11 and CYP17A1 genes was seen in the VAT of obese individuals. Interpretation & conclusions: SAT and VAT exhibited significant differences in terms of the expression of specific genes. These genes might be related to obesity. These findings may be used to improve the clinical diagnosis of obesity and could be a tool leading to the proposal of new therapeutic strategies for the treatment of obesity.

Evaluation of Benzene Exposure and Early Biomarkers of Kidney Damage in Children Exposed to Solvents Due to Precarious Work in Ticul, Yucatán, México.

BACKGROUND: The child labor situation has been associated with precarious job conditions and poor health conditions because children are often exposed to unsafe work environments, stressful psycho-social work conditions, scarce or no access to protective services, and heavy work burdens. OBJECTIVE: The aim of the study was to evaluate markers of exposure to benzene through the exposure biomarker trans, trans-muconic acid (tt-MA), and biomarkers of early renal damage in children who work in sites that are under precarious job conditions. METHOD: Samples of urine were obtained from children (aged 6-12 years old) who resided in Ticul, Yucatan, Mexico. Exposure to benzene was assessed through trans, trans-muconic acid (t,t-MA). Evaluated renal damage biomarkers were: Cystatin-C (Cys-C), Osteopontin (OPN), α1-Microglobulin (α1-MG) and Neutrophil Gelatinase-Associated Lipocalin (NGAL). FINDINGS: Children who live where the workplace is inside the dwelling presented higher mean levels of tt-MA (0.59 mg/g creatinine) compared with those who live away from the workshops (0.19 mg/g creatinine). Likewise, mean levels of NGAL (4.7, 5.2 ng/ml), albuminuria (10, 10 ng/ml), Cys-C (11.8, 7.5 ng/ml), OPN (224.4, 226.5 ng/ml) and α1-MG (96.6, 73.6 ng/ml) were found in children where the workplace was inside the dwelling and outside, respectively. CONCLUSION: Our data indicate that the children who work under precarious job conditions are exposed to benzene, and they exhibit protein levels that suggest renal damage in a population in precarious working conditions. Therefore, the child population should be considered as the most vulnerable and susceptible to suffer adverse health effects.

Frontal Fibrosing Alopecia Severity Index: A Trichoscopic Visual Scale That Correlates Thickness of Peripilar Casts with Severity of Inflammatory Changes at Pathology.

BACKGROUND: Frontal fibrosing alopecia (FFA) is a scarring alopecia that mainly affects postmenopausal women characterized by recession of the frontotemporal hairline and eyebrow loss. Current techniques to assess FFA activity are limited and involve noninvasive tools that assess disease progression or an invasive technique such as scalp biopsies. However, since progression of FFA is very slow, it is very important to develop a noninvasive technique to assess disease activity to monitor treatment response. OBJECTIVES: To provide a standardized and objective method to assess FFA activity. METHODS: We evaluated the correlation between trichoscopy and pathological features (degree of lymphocytic infiltration) in 20 dermoscopy-guided biopsies of FFA. At trichoscopy, we divided the severity of peripilar casts into 3 grades according to their thickness. To validate the trichoscopic visual scale, we showed the images to 7 dermatologists with interest in hair diseases. Concordance was assessed using the Kendall Tau-b concordance test. RESULTS: A strong correlation between severity of peripilar casts at trichoscopy and degree of lymphocytic infiltrate was observed by the Kendall Tau-b test. Validation showed very good inter- and intraobserver agreement. CONCLUSION: The trichoscopic visual scale allows noninvasive assessment of scalp inflammation in FFA in different scalp regions and therefore provides optimal guidance for treatment.

Scalp Itch: A Systematic Review.

Scalp itch is a frequent complaint in the dermatological setting. It is common for the dermatologist to encounter patients with no evident cause of scalp pruritus, making it a distressing situation for both the clinician and the patient. The aim of this paper is to propose a systematic approach to scalp itch, which classifies scalp pruritus into two types: (1) with or (2) without dermatological lesions, and presence or absence of hair loss. Also, it is important to think first about the most common causes and then rule out other, less common etiologies. The acronym SCALLP and the five steps for scalp evaluation (listen, look, touch, magnify, and sample) are useful tools to keep in mind for an assertive approach in these patients.

Short anagen syndrome: Case series and literature review.

BACKGROUND/OBJECTIVES: Short anagen syndrome is a hair cycle disorder usually diagnosed in early childhood and characterized by short hair length due to short duration of the anagen phase. The objective was to review the presentation and demographic characteristics of short anagen syndrome and compare them with the most common differential diagnosis, loose anagen syndrome. METHODS: A retrospective review of eight children with short anagen syndrome was performed at the University of Miami Outpatient Dermatology Clinic. RESULTS: The diagnosis of short anagen syndrome was confirmed according to clinical findings and characteristic short telogen hairs with pointed tips on the hair pull test. CONCLUSION: This is the largest reported clinical series of short anagen syndrome thus far in the literature.

Environmental Risks and Children's Health in a Mayan Community from Southeast of Mexico.

BACKGROUND: The World Health Organization (WHO) estimates that 25% of global morbidity and one-third of childhood morbidity may be attributable to environment. Low and high-income countries displayed different environmental risks. Mexico demonstrates the necessity for creating a national environmental health program. In southeastern Mexico, Tixméhuac, is a Mayan community with a high marginalization degree and social backwardness. The main childhood morbidities are acute and chronic diseases. OBJECTIVE: The aim of the study was to recognize environmental risks for children's health in Tixméhauc, Yucatan State. METHODS: A total of one hundred children under five years old participated. To identify the environmental risks at home, items from the Green Sheet Guidance (WHO), Salamanca General Survey and Environmental Clinical History were used. To know the prevalence of respiratory diseases and asthma, the International Study of Asthma and Allergies in Children (ISAAC) survey was used. Potentially hazardous sites were identified partially using the Methodology for Identification and Evaluation of Health Hazards in Contaminated Sites from the Pan American Health Organization (PAHO). FINDINGS: The low stature of, malnutrition, presence of wheezing and asthma symptoms in children were higher than expected. The suspected cases of parasitosis and vector-borne disease occurred in 50% of the children. Indoor air quality perception was associated with respiratory pathology history; housing quality was related to suspected cases of vector-borne diseases; drinking water quality was linked to suspected cases of parasitosis. Risk areas in the community include agricultural activity, which has led to deposits of empty containers of agrochemicals and electronic waste among solid waste dump. CONCLUSION: This study presents observed environmental risks to children in a low development country and in developing countries. The community has a low perception of the environmental risk. The need for public health programs reducing risks to children's environmental health is imperative.

In vitro determination of Mexican Mestizo hair shaft diameter using optical coherence tomography.

BACKGROUND: Mexican mestizo population has a pluriethnic mixture of Amerindian, European and African ancestry, predominant in most Latin American countries. Until now, there are no reports about hair characteristics in this population, necessary to define normal values, for hair diseases evaluation and comparison among other ethnic groups. METHODS: The VivoSight® swept-source multibeam optical coherence tomography system was used to evaluate hair diameter and shape in 30 females. Three hair samples from each volunteer were measured transversely along three distances, generating nine cross-sectional images, two measurements per image and 18 measurements per patient for a total of 540 diameter measurements. RESULTS: Minimum hair diameter (n = 540) was 0.06 mm while maximum was 0.14 mm. Mean diameter was 0.10 ± 0.01 mm as compared with Asian hair, which ranges from 0.08 mm to 0.12 mm. On morphological analysis, Mexican Mestizo hair tends to have a round shape with homogenous diameters, resembling Caucasian and Asian hair. CONCLUSION: Mexican hair is similar to Asian hair in diameter and shape and can be classified as 'thick' hair, which make it more resistant and with more volume. Cosmetic products intended to improve hair care in this population must to consider this characteristic.

Cost Effectiveness of Intracranial Pressure Monitoring in Pediatric Patients with Severe Traumatic Brain Injury: A Simulation Modeling Approach.

OBJECTIVES: To conduct an economic evaluation of intracranial pressure (ICP) monitoring on the basis of current evidence from pediatric patients with severe traumatic brain injury, through a statistical model. METHODS: The statistical model is a decision tree, whose branches take into account the severity of the lesion, the hospitalization costs, and the quality-adjusted life-year for the first 6 months post-trauma. The inputs consist of probability distributions calculated from a sample of 33 surviving children with severe traumatic brain injury, divided into two groups: with ICP monitoring (monitoring group) and without ICP monitoring (control group). The uncertainty of the parameters from the sample was quantified through a probabilistic sensitivity analysis using the Monte-Carlo simulation method. The model overcomes the drawbacks of small sample sizes, unequal groups, and the ethical difficulty in randomly assigning patients to a control group (without monitoring). RESULTS: The incremental cost in the monitoring group was Mex$3,934 (Mexican pesos), with an increase in quality-adjusted life-year of 0.05. The incremental cost-effectiveness ratio was Mex$81,062. The cost-effectiveness acceptability curve had a maximum at 54% of the cost effective iterations. The incremental net health benefit for a willingness to pay equal to 1 time the per capita gross domestic product for Mexico was 0.03, and the incremental net monetary benefit was Mex$5,358. CONCLUSIONS: The results of the model suggest that ICP monitoring is cost effective because there was a monetary gain in terms of the incremental net monetary benefit.

The Hair Shedding Visual Scale: A Quick Tool to Assess Hair Loss in Women.

INTRODUCTION: Hair shedding is a common consequence of the normal hair cycle that changes with internal and external factors. Female pattern hair loss (FPHL) is difficult to assess in terms of shedding severity as the conscious perception of hair shedding varies according to each individual, and most utilized methods are semi-invasive or very time consuming. In this study, we establish and validate a hair-shedding scale for women with thick hair of different lengths. METHODS: A visual analog scale was developed for thick hair of short, medium, and long lengths by dividing a bundle of hairs of each length into nine piles of increasing hair amount that were then photographed and arranged in order of size. Twenty women with no FPHL with each length of hair (60 total) were asked to select the photographed hair bundle that best correlated with the amount of hair they shed on an average day. A total of 94 women with FPHL with excessive shedding were then asked to repeat the same process. RESULTS: Women with no FPHL and short, medium and long hair had mean shedding scores of 2.5, 2.35 and 2.4, respectively. Women with FPHL and short, medium and long hair had mean shedding scores of 7.25, 7.0 and 7.14, respectively. Statistically significant Spearman's ρ coefficient and κ coefficient demonstrated correlation and inter-observer reliability. CONCLUSION: Our results show that women with FPHL not only shed considerable hair more than women with no FPHL, but that this hair-shedding visual scale is a fast and effective method of evaluating hair-shedding amounts in an office setting.

Paraoxonase 1 and its relationship with pesticide biomarkers in indigenous Mexican farmworkers.

OBJECTIVE: Biomarkers of pesticide toxicity and paraoxonase 1 (PON1) phenotype and genotypes were evaluated in indigenous Mexican farmworkers exposed mainly to organophosphate (OP) pesticides. METHODS: Acetylcholinesterase, butyrylcholinesterase, and PON1 activities--arylesterase and CMPAase activities--were evaluated spectrophotometrically. PON1 55 and 192 polymorphisms were determined by real-time polymerase chain reaction. Hematological parameters were evaluated using a cytometer. RESULTS: Butyrylcholinesterase and arylesterase activities were lower in farmworkers, who also showed lower levels of leukocytes but higher percentages of lymphocytes when compared with the nonexposed group. Our results showed a high frequency of OP, high hydrolysis-related PON1 alleles (LL/QR and LL/RR) in the study population. An association was observed between CMPAase activity and PON1Q192R polymorphism. CONCLUSIONS: Our results suggest that pesticide exposure modifies biochemical and hematological biomarkers in the study population, and that the phenotype of PON1 (CMPAase) is a sensible susceptibility biomarker of OP pesticide toxicity.