Genotoxic monitoring and benzene exposure assessment of gasoline station workers in metropolitan Bangkok: sister chromatid exchange (SCE) and urinary trans, trans-muconic acid (t,t-MA).

Early warning of the potential of mutagens or carcinogens caused by benzene exposure that might occur in gasoline station workers can be achieved by examining 2 major biomarkers: sister chromatid exchange (SCE) and trans, trans-muconic acid (t,t-MA), a urinary metabolite of benzene. The main objective of this study was to assess benzene exposure and monitor the genotoxic effect of gasoline station workers in Bangkok, Thailand. Blood and urine samples were collected from 33 gasoline station workers, working in Pathumwan district area, central Bangkok, Thailand, for SCE and t,t-MA analysis, from April to June 2009. Control samples were collected from 30 office workers and students in the same area at the same period. Our results indicated significantly higher frequencies of SCE in gasoline exposed workers were than in controls (p<0.01), independent of gender. Urinary t,t-MA and t,t-MA/creatinine levels of gasoline exposed workers were also significantly higher than the control groups (p<0.05) were significantly higher in women than men workers (p<0.01). Calculated chromosomal damage relative risk (RR) of gasoline station workers was 3.00 (95% CI = 1.81 - 4.98, p<0.001) compared to controls. The gasoline exposed workers had potentially higher risk of chromosomal damage and cancer development because of direct contact to benzene.

A correlative study on red blood cell parameters and urine trans, trans-muconic acid in subjects with occupational benzene exposure.

Benzene is of particular concern because of recent research indicating that benzene exposure can result in toxicity. The hematotoxic effect of benzene is mentioned. However, there is little knowledge about the correlation between the biomarker of benzene exposure and changes in red blood cell parameters. Here, the correlation between the urine trans, trans-muconic acid (ttMA) level and red blood cell parameters were studied in 30 Thai subjects at risk. The regression analysis shows no significant correlation between urine ttMA and any studied red cell parameters (Hb, MCV or MCH). Based on our hematologic data, we proposed that only investigation for the urine ttMA might be not sufficient in detection of alteration in red blood cell parameters in the exposed population. Combinations between biomarker and hematological test are recommended.

Detection of Cryptococcus neoformans in bird excreta.

We evaluated 14 samples of bird excreta from pigeons, parrots, open billed storks and crows obtained from thirteen places in Bangkok and nearby areas between April and July 2004. These bird excreta were examined for Cryptococcus neoformans by direct plating method to inspect their ability to grow at 37 degrees C. Capsule production was examined by Indian ink preparation. They were also tested for urease and phenoloxidase enzymes. Cryptococcus neoformans var neoformans was recovered from pigeon excreta in 9.09%. This implies those having impaired immunity may get this fungus from the environment.

High sister chromatid exchange among a sample of traffic policemen in Bangkok, Thailand.

There are several volatile substances from the traffic, including benzene, toluene, carbon monoxide, lead and formaldehyde. Most of these substances are considered carcinogens. Police are at occupational risk for toxic fume exposure. This study compared sister chromatid exchange (SCE), a marker for genotoxicity, among a sample of Thai traffic policemen in Bangkok with healthy control subjects. Thirty police officers (all male) and 20 controls were included in this study. The average (mean+/-SD) SCE for policemen and controls were 4.40+/-0.93/cell and 0.24+/-0.12/cell, respectively. A significantly higher SCE among the policemen was observed. Concern for and prevention of toxic substance exposure in traffic police officers should be made a national goal.

Lead intoxication: a summary of the clinical presentation among Thai patients.

Lead is an important toxic metal found in industrial communities. Due to the industrialization in the recent decade in Thailand, lead intoxication as a toxicant-related disorder becomes a new public health problem. A retrospective study on clinical presentation of hospitalized patients with diagnosis of lead intoxication during year 1990-1999 in King Chulalongkorn Memorial hospital, the largest Thai Red Cross Society Hospital, was performed. All 14 cases diagnosed with lead intoxication were identified in our series. Average age of the subjects was 25.55 +/- 21.93 years old. Male predominance was detected in our series (male:female = 12:2). Two main groups of subjects as; (1) childhood aged below 10 years old (male:female = 4:2) and (2) adult aged between 24 and 60 years old (n = 8, all male), can be identified. For the first group, the clinical presentations were convulsion (n = 3), unexplained anemia (n = 1), attention deficit (n = 1) and asymptomatic (n = 1), respectively. All of the subjects in this group presented the history of living at the old battery plant area. Five of the six cases came from the same village. For the second group, the clinical presentations were unexplained abdominal pain (n = 5), chronic renal failure (n = 1), unexplained anemia (n = 1) and asymptomatic (n = 1), respectively. Most of the subjects (75%) in this group presented the history of working in the battery plant for more than 10 years. Another case presented the history of gunshot and residual bullet in the bone marrow. The other one left is an interesting case with the history of prolonged usage of ritual pill and holy paper incineration. Like other studies, battery plant had strong relation with the lead intoxication. Although the total identified cases are rather few, there may be more undetected asymptomatic lead intoxication cases in the community. Specific control of lead resulted from battery plant and monitoring of the workers as public health strategies are still recommended.

White blood cell sister chromatid exchange among a sample of Thai subjects exposed to toluene, an observation.

There is a particular concern with toluene because some research has indicated that toluene exposure could result in chronic toxicity including mutagenesis and carcinogenesis. This study aimed to determine the rate of sister chromatid exchanges (SCE), a marker for genotoxicity, and its correlation to the classical urine biomarker for toluene exposure, urine hippuric acid, among a sample of Thai exposed subjects. A total of 26 police (all males) were included in this study. The average (mean +/- SD) urine hippuric acid level in these police was 0.8 +/- 0.4 mg/g creatinine. The average (mean +/- SD) SCE level in these police was 4.5 +/- 1.0/cell. The average SCE among the police with high urine hippuric acid levels was non-significantly higher than the average SCE level of those without (P = 0.41). This implies that the cytogenetic response to toluene was not different between the subjects with and without high toluene exposure. High exposure to toluene seems not to be related to high SCE.

The effect of green pit viper (Trimeresurus albolabris) venom on platelet morphology by electron microscopy.

The incidence of venomous snake bites increases every year in Thailand, especially due to green pit viper. After the bite, there is bleeding due to thrombin-like property of the venom. The mean platelet volume has been reported to be decreased in those who have been bitten by this snake. In this study we investigate the effect of green pit viper venom (Trimeresurus albolabris) on platelet volume (MPV), number and morphology of platelets in vitro. The test was carried out by washing platelets in phosphate buffer at pH 7.2 to remove fibrinogen, then the washed platelets were mixed with green pit viper venom. Platelet morphology was examined by scanning electron microscope (SEM). The morphology of platelets was smaller than normal which ranges from 1.1- 1.2 microm. Green pit viper venom can directly effect platelet morphology, decreasing platelet volume.

Cancer risk for Thai traffic police exposed to traffic benzene vapor.

Benzene exposure is of particular concern because recent research indicates that it can result in chronic toxicity, with an elevated risk of carcinogenesis. Exposure to benzene from automobile exhaust can be an important occupational problem for police. The present study was conducted to estimate risk of Thai traffic police developing cancer due to contact with traffic benzene vapor during daily work. According to the data obtained, the estimated predicted cancer incidence for traffic police is 0.05 case per 70-year period, simply translated as 1.8 cancer cases per 100,000 traffic police per year. This is clearly a cause of concern and annual check up and monitoring for benzene exposure among traffic police should be set up as part of a program for primary prevention of occupation -- related cancer.

Monitoring of urine trans, trans-muconic acid level among smokers and non-smokers.

Smoking has contributed to various neurological, cardiovascular, and pulmonary diseases. According to carcinogens found in cigarette smog, benzene is one of the important carcinogenic compounds. The urinary trans, trans-muconic acid (ttMA) levels among a sample of 10 Thai smokers and 35 Thai non-smokers were investigated, compared and reported. The average urinary ttMA level in smokers and non-smokers were 2.19 +/- 2.32 and 0.24 +/- 0.33 mg/gCr, respectively. A significant higher urinary ttMA level among the smokers was observed (P < 0.05). Since the higher urinary ttMA indicates the higher occult risk for cancer, the usage of urinary ttMA is recommended as a monitoring tool to follow up benzene exposure in the smokers.

Feasibility of using papaya skin extract for digestion of swamp eel viscera for harvesting infective stage larva of Gnathostoma spp.

In this study, we reported the feasibility of using papaya skin extract (Carica papaya L.) as an alternative to enzyme pepsin in harvesting Gnathostoma spinigerum third-stage larvae. From experimental digestion, we found that the different numbers of recovered larvae between papaya skin extract and pepsin were not statistically significant (p >0.05). When the derived larvae from pepsin and papaya skin extract digestion were cultivated in BME medium for 7 days, the survival rates were not significantly different either (p >0.05). Thus, papaya skin extract might be another choice for recovering Gnathostoma spinigerum third-stage larvae.

Urine phenol and myeloperoxidase index: an observation in benzene exposed subjects.

Benzene is a colorless poisonous liquid with a sweet odor. At present, it is documented as a known inducer of leukemia. Potential metabolic mechanisms underlying the hemopoietic toxicity of benzene include bioactivation of phenolic metabolites of benzene by myeloperoxidases in bone marrow, which results in hydroquinolone, a major leukemogen. There is no previous correlative study between the level of phenol, urine benzene metabolite, and the myeloperoxidase index (MPXI). Here, the correlation between the urine phenol and MPXI were studied in 24 Thai subjects occupationally exposed to benzene. Of interest, the regression analysis show no significant correlation between urine phenol level and MPXI (r = -0.05, P = 0.81).

Blood carboxyhemoglobin level and platelets: a correlation study.

The high level of air pollution is an important problem. One of these major pollutants is carbon monoxide (CO), which can block normal physiology. Hematologic alteration is another important side effect of exposure to CO. Adverse effects on red blood cells, formation of nonfunctional hemoglobin called carboxyhemoglobin (COHb), have been well documented. The effect of CO on platelets is not well documented. Therefore, the correlation between the level of blood COHb and the platelet count was evaluated in 28 subjects exposed to CO. There is no statistical significance; however, decreased platelet count, platelet distribution width, and plateletcrit, and an increase in blood COHb were observed.

Effect of smoking on platelet count and platelet parameters: an observation.

Arterial thrombosis occurs with increased frequency in cigarette smokers. It is believed that disturbance of platelet function, especially aggregation, is the essential mechanism responsible for this pathology. However, the effect of smoking on the quantity of platelets might be another contributing factor. The effect of smoking on platelet count is still controversial. We performed a cross section-al study to compare the platelet count and platelet parameters in Thai police who are smokers and non-smokers. A total of 30 Thai police in Bangkok were included in this study. Of the 30 police, there are 5 non-smokers and 25 smokers. The platelet counts and platelet parameters of the subjects were not significantly different between smokers and non-smokers.

Causative agents of liver abscess in Thai hepatitis B carriers.

Liver abscess and hepatitis B virus (HBV) infection are two significant tropical gastrointestinal disorders. The concurrence between these two disorders yields poor prognosis, which then often leads to the need for intensive care. The aim of this study was to investigate the causal pathogens of liver abscess in HBV carriers. This retrospective case review was conducted on 35 Thai hospitalized HBV carriers who had diagnosis of liver abscess. A high rate of amoebic liver abscess in this series (37.1%) was demonstrated; Gram-negative aerobes were the major abscess pathogens. The causative pathogens of HBV carriers were similar to those in the overall patient population with abscess. The treatment plan for liver abscess in the general population can also be applied to HBV carriers.