Occupational hand dermatitis among cement workers in Taiwan.

BACKGROUND/PURPOSE: Occupational dermatitis among cement workers is a major occupational health concern. The two most important occupational hazards for cement workers are irritant and allergic cement contact dermatitis. The objective of this study was to investigate the severity of occupational cement contact dermatitis and the common allergens among cement workers in Taiwan. METHODS: A total of 97 cement workers from the Cement Workers' Association of Tainan City and County participated in this study. A structured questionnaire was used to evaluate the demographic data and work-related activities of these cement workers. A complete skin examination was conducted, and skin manifestations were assessed by a dermatologist. Allergens from European Standard Tray (Chemotechnique Diagnostic AB, Sweden) with a total of 25 substances were used for patch testing. RESULTS: Our results showed that 65 out of 97 cement workers were suffering from occupational cement hand contact dermatitis. The most affected skin area was the hand. Thickening of the dorsal surface of the hand, especially around the metacarpophalangeal joint area, and hyperkeratosis of the palm were the major skin manifestations. The results of the patch test showed that 24 out of 97 were allergic to potassium dichromate, nine were allergic to thiuram mix, nine were allergic to fragrance mix and seven were allergic to cobalt chloride. The final diagnosis, based on the results of the skin examination and the patch test, showed that 43 of 97 cement workers had irritant cement contact dermatitis and 22 had allergic cement contact dermatitis. CONCLUSION: We conclude that occupational cement hand dermatitis among cement workers is an important and severe issue in Taiwan, and the most common allergens among cement workers are potassium dichromate, thiuram mix, fragrance mix and cobalt chloride. The high positive rate of chromium hypersensitivity among cement workers reflects the urgency to regulate the addition of ferrous sulfate to cement in Taiwan.

N-acetylcysteine inhibits chromium hypersensitivity in coadjuvant chromium-sensitized albino guinea pigs by suppressing the effects of reactive oxygen species.

BACKGROUND: Chromium hypersensitivity is an important issue in occupational skin disease. When hexavalent chromium enters the cell, it can be reduced to trivalent chromium, resulting in the formation of reactive oxygen species (ROS). ROS are considered to play an important role in the progression of allergic contact dermatitis. N-acetylcysteine (NAC) could increase glutathione levels in the skin and act as an antioxidant. AIMS: We attempted to demonstrate that NAC could inhibit chromium hypersensitivity in a coadjuvant chromium-sensitized albino guinea pig model by counteracting the formation of ROS. METHODS: We utilized a coadjuvant chromium-sensitized albino guinea pig model to evaluate both the severity of the skin reaction by intradermal and epicutaneous elicitation tests and the sensitization rate of chromium hypersensitivity in NAC-treated and NAC-untreated albino guinea pigs (GP). Furthermore, three ROS parameters, including H(2)O(2,) malondialdehyde (MDA) levels in the skin and the oxygen radical absorbance capacity (ORAC) in plasma, were analyzed in NAC-treated and NAC-untreated coadjuvant chromium-sensitized albino GP. RESULTS: The severity of the skin reaction in the intradermal and epicutaneous elicitation test significantly diminished when the albino GP were treated with a dose of 1200 mg/kg/day of NAC. This dose also significantly decreased the sensitization rate of chromium hypersensitivity. In addition, treatment with 1200 mg/kg/day of NAC significantly reduced the H(2)O(2) and MDA levels in the skin and significantly increased the ORAC in the plasma of albino GP. Therefore, NAC could be a potential chemopreventative agent to prevent the progression of chromium hypersensitivity.

Skin penetrating abilities and reservoir effects of neat DMF and DMF/water mixtures.

This study was set out to determine the skin permeabilities of neat N, N-dimethylformamide (DMF, denoted as DMF(100%)) and DMF/water mixtures (including 50% DMF/50% water and 10% DMF/90% water mixtures (v/v), denoted as DMF(50%) and DMF(10%), respectively) and to assess their skin reservoir effects on the systemic absorption. The penetration fluxes for DMF(10%) and DMF(50%) (=0.015 and 0.126 mg/cm(2)/h, respectively) were only approximately 1.1%and 15% in magnitude as that of DMF(100%) (=0.872+/-0.231 mg/cm(2)/h), respectively. The above results could be because the perturbation effect of the DMF content was much more significant than the rehydration effect of the water content on skin permeability. We found that 85.9%, 96.6% and 98.7% of applied doses were still remaining on the skin surface, 4.98%, 0.838% and 0.181% were still remaining in the skin layer, and 9.09%, 2.61% and 1.17% penetrated through the skin layer after the 24-h exposure for DMF(100%), DMF(50%) and DMF(10%), respectively. We found that the half-life (T(1/2)) of DMF retaining in the skin layer were 12.3, 4.07 and 1.24h for DMF(100%), DMF(50%) and DMF(10%), respectively. The estimated reservoir effect for DMF(100%) (=34.1%) was higher than that of DMF(50%) and DMF(10%) (=27.1% and 14.1%, respectively). The above results suggest that the impact associated with the internal burden of DMF could be prolonged even the external exposure of DMF is terminated, particularly for those dermal contact with DMF/water mixtures with high DMF contents.

Assessment of airborne and dermal exposure to 2-ethoxyethyl acetate in an occupational environment.

BACKGROUND: Because of its chemical-physical properties, 2-ethoxyethyl acetate (EEAc) can penetrate through the skin. However, no actual occupational environmental studies or empirical dermal exposure measurements have been performed. METHODS: Twenty workers from a commercial label silk screening shop were recruited and they completed a questionnaire of demographic information. Environmental monitoring of EEAc exposure via respiratory and dermal routes was performed for five consecutive working days. RESULTS: Airborne EEAc concentration was over the permissible exposure limit of 5 ppm in 90% of the participants. The dermal EEAc concentration was highest on the palms. The EEAc concentration correlated with skin exposure level (P < 0.001). The dermal EEAc concentrations in individuals who did not wear gloves were higher than in those who wore gloves. CONCLUSIONS: EEAc on the skin is strongly associated with airborne EEAc. Wearing impermeable gloves during high-risk tasks (cleaning process) can reduce EEAc dermal exposure on the palms.

Effect of smoking on blood lead levels in workers and role of reactive oxygen species in lead-induced sperm chromatin DNA damage.

OBJECTIVE: To investigate whether cigarette smoking affects the blood lead levels (BLL) and whether exposure to lead introduces sperm chromatin DNA damage in factory workers. DESIGN: Cross-sectional study. SETTING: A battery plant in Taiwan. PATIENT(S): Eighty male workers employed within a battery plant. INTERVENTION(S): Standard semen analysis was performed according to the World Health Organization guidelines. MAIN OUTCOME MEASURE(S): Assessment of BLL, sperm chromatin DNA structure, reactive oxygen species generation and other conventional parameters of semen quality. RESULT(S): As compared with nonsmoking workers, the BLL were found to be considerably higher among smokers. Statistically significant differences were found in the sperm DNA denaturation (alphaT) induction and the percentage of sperm with increased DNA denaturation (COMP alphaT) in workers with moderate BLL (>or=25 microg/dL). After adjustment for smoking propensity, a positive correlation was discernible between BLL and alphaT, COMP alphaT, and morphologic abnormality. Furthermore, alphaT and COMP alphaT were also found to have positive correlations with sperm superoxide anion production. CONCLUSION(S): Workers with higher BLL were found to be at a higher risk of sperm morphologic abnormality and chromatin DNA integrity. These data are significant because they can facilitate the estimation of lead exposure in reproductive toxicology.

Asthma-like syndrome in school children after accidental exposure to xylene and methylene diphenyl diisocyanate.

BACKGROUND AND PURPOSE: We assessed the signs and symptoms, pulmonary function changes and residual chemical body burden of school children in the vicinity of an accidental exposure to volatile xylene and methylene diphenyl diisocyanate (MDI). METHODS: After the exposure episode, children with significant symptoms after MDI exposure (e.g., dizziness, nausea, sore throat, and breathing difficulties) were sent to nearby emergency medical units for evaluation and admission if necessary. Clinical work-up included pulmonary function tests and measurement of residual MDI in the body by high-performance liquid chromatography analysis of urine. RESULTS: 203 students appeared to develop symptoms associated with contaminant exposure, and 173 affected students were sent to nearby emergency units. In the subsequent surveillance, 22 of 203 affected students (10.8%) revealed a positive history of asthma, which was strongly correlated with the incidence of dyspnea arising from the incident. For children with no previous history of asthma, 60.8% (110 of 181) complained of dyspnea during the episode, and 16.2% required inhaled bronchodilator therapy at the emergency medical units for relief of wheezing symptoms. In a simulation, we found the raw material used for tract surfacing, primarily MDI dissolved in xylene, to be present at a concentration (870 ppm w/w) more than 8000-fold the level defined as safe for a working environment. CONCLUSIONS: We have detected a direct cause-effect relationship between the accidental spillage of MDI and the appearance of an acute asthma-like syndrome among previously unexposed school children.

Effect of hand dermatitis on the total body burden of chromium after ferrous sulfate application in cement among cement workers.

BACKGROUND: Ferrous sulfate (FeSO(4)) added to cement has been used to reduce the prevalence of dermatitis in workers. However, the effect of dermatitis on the total uptake of chromium in cement with or without FeSO(4) has not been previously explored. OBJECTIVE: The objective of this study was to compare the urinary chromium levels before and after FeSO(4) addition among cement workers with or without hand dermatitis. METHODS: Thirty-five male workers were recruited in this study for two consecutive years: 2003 without using FeSO(4) and 2004 after adding FeSO(4). Urinary chromium was used as a biomarker to estimate the total body burden of chromium. RESULTS: Urinary chromium concentration showed significant decreases after FeSO(4) was used, and a larger decrease of urinary chromium was observed in workers with hand dermatitis than for those without hand dermatitis. Moreover, a significant decrease of urinary chromium was observed in workers with hand dermatitis in both 2003 and 2004. CONCLUSION: FeSO(4) decreases the total body burden of chromium, especially in workers with severe and continuous hand dermatitis.

The total body burden of chromium associated with skin disease and smoking among cement workers.

BACKGROUND: Hand eczema and other skin diseases have been associated with the exposure of chromium among cement workers. Studies on skin disease and other factors associated with the body burden of chromium are limited. OBJECTIVE: The present study investigated the role of skin disease and smoking in the association with body burden of chromium among cement workers. METHODS: Forty-five workers (38 men and 7 women) were recruited for this study and interviewed to obtain information on demographic status, lifestyle, employment history, and affecting factors. Urine samples were collected to measure the urinary chromium concentration to represent the body burden of chromium. RESULTS: The average urinary chromium concentration was approximately 6 times higher in non-smoking workers with hand eczema than in non-smoking workers with no skin disease (45.5 vs. 7.6 microg/L). The average chromium level increase to 87.0 microg/L for smokers with the disease. Compared with workers with no hand eczema, the odds ratio of having urinary chromium concentration exceeding the biological exposure index level significantly increased to 11.6 (95% CI=1.3-102.2) for non-smoking workers with skin disease, and to 48.0 (95% CI=4.5-510.8) for smoking workers with skin disease. The multiple regression analysis showed that the use of gloves may reduce significantly the chromium exposure. CONCLUSIONS: Inadequate protection and personal behavior increase the internal dose of chromium in cement workers. Total body burden of chromium are higher among cement workers with skin disease and smoking habit. These workers deserve intervention education on personal hygiene to reduce the exposure of chromium.

Urinary excretion of toluene diisocyanates in rats following dermal exposure.

Toluene diisocyanates (TDI) are commonly used in polyurethane (PU)-related products. TDIs have been documented as the leading cause of occupational asthma. Skin exposure to TDI in the workplace is common. However, no studies in the literature have investigated the exact biomarker concentration profile for skin TDI absorption through any in vivo animal studies. In this study a rat model was used to evaluate the TDI skin absorption to explore the dose-response pattern and to determine the kinetic characteristics of urinary toluene diamine (U-TDA) during skin exposure. TDIs were topically exposed on the dorsum of rat skin at 0.2%, 1% and 5%. Consecutive urine samples were collected for 6 days and U-TDA were analysed using GC/ECD. It was demonstrated in this rat study that absorption of 2,4- and 2,6-TDI through skin contact is possible. A clear dose-dependent skin absorption relationship for 2,4- and 2,6-TDI was demonstrated by the AUC, Cmax findings and accumulative amounts (r > or = 0.968). U-TDA concentration profiles in 6-day consecutive urine samples fit well in the first-order kinetics, although higher order kinetics could not be excluded for the high dose. The apparent half-lives for excretory urinary TDA were about 20 h consistent at various skin exposures. It is concluded that skin absorption of TDI was confirmed in a rat model and a clear dose-dependent skin absorption relationship for 2,4- and 2,6-TDI was demonstrated. Excretory U-TDA concentrations in 6-day consecutive urine samples via skin exposure reveal the first-order kinetics and the half-lives were about 20 h.

Combining novel strategy with kinetic approach in the determination of respective respiration and skin exposure to N,N-dimethylformamide vapor.

N,N-dimethylformamide (DMF) could be readily absorbed via skin and inhalation routes. It is difficult, however, to separate the internal dose contribution from skin vapor and inhalation exposure. This study attempts to quantitatively determine the separate skin vapor and inhalation exposure contributions using a semi-actual exposure approach. Six volunteers were tailgated by DMF-exposed employees completely for two exposure scenarios: with and without wearing a respirator. Individual airborne DMF (A-DMF) exposure was evaluated by integrating real-time DMF monitoring and time-activity log. Urinary N-methylformamide (U-NMF) concentrations in 4-h and 8-h one urine sample plus 24-h consecutive urine sample were determined to evaluate the internal DMF exposure dose. The average A-DMF concentrations for all participants were 8.10 (2.75) and 9.52 (3.47) ppm, respectively, for with respirator and without respirator scenarios. Area under the curve of U-NMF throughout 24-h showed 71% and 29% contribution from skin and inhalation exposure, respectively, indicates that the absorbed dose of DMF via skin vapor exposure was much greater than inhalation. In conclusion, the semi-actual approach provides a novel measure to accurately determine the relative skin vapor and inhalation exposure contributions to the internal dose. The skin vapor exposure deserves more attention in the prevention of chemical hazards in the exposed environment.

Hematological follow-up of an intervention program adding rubber glove-wearing to local ventilation for 2-ethoxyethanol acetate-exposed workers.

The objective of this study was to evaluate an intervention program, implemented in year 1999, of wearing rubber gloves in addition to engineering control, and to follow-up the hematological effects of 2-ethoxyethanol acetate (2-EEA) exposure among workers in a silk-screening factory. All workers from the printing department with direct exposure to 2-EEA were recruited as the exposed group. Workers from the other departments were recruited as the comparison group. Hematological parameters were measured during health surveys conducted 3 times every two years. Information on personal characteristics and working habits was obtained through a structured questionnaire. More female workers were involved in manual printing resulting in higher exposure to 2-EEA. Hemoglobin and haematocrit levels in female exposed workers were significantly lower than those of female comparison workers in the 1st (1998) health survey, but not in the 2nd (2000) and 3rd (2002) health surveys. No difference was found between male exposed and comparison workers for all three surveys. Longitudinal analysis after adjusting for confounders using the general estimating equation model showed the hemoglobin, haematocrit, and RBC count were significantly higher for 2-EEA exposed workers than comparison workers across the 3 surveys (n=42). The results show that wearing rubber gloves in addition to local ventilation was effective at preventing direct dermal exposure to 2-EEA and ameliorated the hematological effects of 2-EEA exposure.

Improved analysis of dialkylphosphates in urine using strong anion exchange disk extraction and in-vial derivatization.

Determination of dialkylphosphates (DAPs) in urine is useful for assessing human exposure to organophosphates (OPs). An improved method for the determination of four DAPs based on a strong anion exchange (SAX) disk extraction and in-vial derivatization was presented in this study. The matrix effect of urine components such as chloride ion and phosphate ion by using a SAX disk to extract DAPs in urine analysis was carefully evaluated. It was observed that the chloride ion mainly affected the extraction of diethylphosphate (DEP), dimethylthiophosphate (DMTP), and diethylthiophosphate (DETP) in urine. The addition of silver hydroxide could significantly improve the extraction efficiencies of these three DAPs, but it decreases the extraction efficiencies of dimethyldithiophosphate (DMDTP) and diethyldithiophosphate (DEDTP). The LOD of this method for DMTP, DETP, DMDTP, and DEDTP are 5, 5, 11, and 5 microg/L, respectively. A pretreatment strategy for the determination of DMTP, DMDTP, DETP, and DEDTP in urine was proposed which can provide reliable and prompt determination of routine urine analysis.

Mitochondrial DNA alterations in blood of the humans exposed to N,N-dimethylformamide.

N,N-Dimethylformamide (DMF) has been widely used in industries because of its extensive miscibility with water and solvents. Its health effects include hepatotoxicity and male reproductoxicity, possibly linked with mitochondrial DNA (mtDNA) alterations including mtDNA common deletion (DeltamtDNA(4977)) and mtDNA copy number. The relationship between DMF exposure and mtDNA alterations, however, has not been postulated yet. The purposes of this study were to investigate whether the DMF exposure is associated with DeltamtDNA(4977) and mtDNA copy number and to evaluate the DMF-derived mtDNA alterations are more associated with exposure to the airborne DMF concentrations or to the levels of two urinary DMF biomarkers of N-methylformamide (NMF) and N-acetyl-S-(N-methylcarbamoryl) cysteine(AMCC). Thirteen DMF-exposed workers and 13 age and seniority-matched control workers in a synthetic leather factory were monitored on their airborne DMF, NMF and AMCC in the urine as well as DeltamtDNA(4977) and mtDNA copy number in blood cells. We found that the frequencies of relative DeltamtDNA(4977) in DMF-exposed group were significantly higher than those in the control group. Moreover, elevation in the proportion of DeltamtDNA(4977) of individuals with high urine AMCC (U-AMCC) and airborne DMF levels were significantly higher than those without. We conclude that long-term exposure to DMF is highly associated with the alterations of mtDNA in urine and blood cells. The DeltamtDNA(4977) was more significantly related to repeated exposure to DMF and mtDNA copy number was more closely related to short-term DMF exposure. We also confirmed that U-AMCC is more appropriate to serve as a toxicity biomarker for DMF exposure than U-NMF. Further study with a larger number of subjects is warranted.

Alterations in health examination items and skin symptoms from exposure to ultra-low humidity.

OBJECTIVES: Several lines of evidence have shown that insufficient humidity could result in health problems but no studies have been performed in ultra-low humidity (ULH) environments. The aims of this study are to investigate the health examination items alterations and skin symptoms of workers exposed to ULH environment based on a longitudinal study design. METHODS: Twelve male ULH (RH = 1.5%) workers and 12 age-sex-matched reference workers were selected. The examination items in blood and urine as well as the skin problems were compared between ULH workers and controls, and between ULH workers in 2000 and 2003. Biochemistry analysis of blood and urine were implemented from annual health examinations. Information on skin symptoms and diseases were obtained from a structured questionnaire in 2000 and 2003. RESULTS: The alterations in mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and total cholesterol in blood analysis and only sediment-WBC in urine analysis were found significantly different in 2000. These changes were almost fully recovered in 2003 although a consistently significant elevation in the urine specific gravity was found during the 3-year follow-up period. Skin disorders, however, showed an earlier elevated itching symptom in lower limb and pretibial that developed to physician-diagnosed contact dermatitis. CONCLUSIONS: Long-term ULH exposure could cause progressive pathological changes in the skin and urine concentration elevation. Because low humidity condition occurs frequently in air-conditioned buildings, the findings of this study suggest the population long-term exposed to low humidity should be cautious about health manifestations living in a low humidity environment. While the indoor environment is equipped with an air-conditioner, continuous monitoring on the humidity is recommended.

Microwave-assisted acid hydrolysis of toluene diamine conjugates in urine samples for biomarkers in toluene diisocyanate analysis.

Toluene diamines (TDAs) in urine have been used widely to determine the amount of toluene diisocyanate (TDI) absorbed by humans. Conventional hydrolysis to prepare a sample of urine takes approximately 16h. An attempt is made to apply microwave-assisted heating (MAH) to reduce the duration of analysis. Urine collected from rats exposed to a mixture of 2,4- and 2,6-TDI was diluted with non-exposed human urine 1/1250-, 1/500- and 1/250-fold. The urine samples were hydrolyzed by both conventional heating and MAH. The hydrolysis efficiency obtained using MAH significantly exceeded that obtained using conventional heating. Hydrolysis by MAH required only 20min, 48 times faster than with conventional heating. The use of the MAH method in hydrolysis was demonstrated to be reproducible, timesaving and efficient technique in measuring the concentration of urinary TDAs.

Using urine specific gravity to evaluate the hydration status of workers working in an ultra-low humidity environment.

In environments with ultra-low humidity, workers may have excessive body water loss due to evaporation through the skin, which can lead to dehydration. Before the development of clinical symptoms and signs, concentrated urine may be applied as an early indicator of dehydration. We used urine specific gravity (USG) as a biomarker to evaluate the hydration status of workers working in such an environment. We collected the urine samples from workers at a lithium battery plant during their annual health examination, and the relative humidity of some working areas called "dry rooms" in the plant was 1.5 +/- 1%. We recruited workers in those dry rooms as the exposure group (N=50) and defined the remaining workers, including administration office workers, as the comparison group (N=122). The prevalence of abnormally concentrated urine (USG>1.030) and related factors were compared between these two groups. While the exposure group were younger and had shorter employment durations compared to the comparison group (p<0.05), they had a higher prevalence of abnormally concentrated urine (p<0.01). After adjusting for age, gender, employment duration, and body surface area, we found that working in the dry rooms was associated with an odds ratio of 11.9 (95% confidence interval: 2.5 to 56.9) of having abnormally concentrated urine. Therefore, USG is a good biomarker for evaluating the hydration status of workers working in ultra-low humidity environments, who need proper protection and adequate fluid supply to prevent excess water loss and its adverse health effects.

The development and regulation of occupational exposure limits in Taiwan.

The occupational exposure limits (OELs) in Taiwan was promulgated in 1974 and has been revised five times since then. Many of the OELs were adopted from the most recent ACGIH TLVs and US OSHA PELs. A total of 483 chemicals were listed in the current Taiwan OELs Standard. The procedures of OELs development in Taiwan include the IOSH organized a recommended exposure limits (RELs) Committee to select the target chemicals and to recommend the RELs through literature review based on the health effects in the first stage, then, the CLA put policy needs, economical and technical feasibility into consideration and set up the final OELs at the second stage. A standard operation manual of RELs Committee has been developed. Based on our experience, several issues including the participation of representatives from a comprehensive spectrum, communication/education and training/enforcement, continuous collection of the local exposure data and health hazard information, use of health risk assessment, consideration of economic, and technical feasibility, as well as the globalization and information and experience sharing are critical in developing the appropriate OELs. Three examples including benzene, crystalline silica, and 2-methoxy ethanol are given to demonstrate the operation of system.

Electrocardiographic abnormality for workers exposed to carbon disulfide at a viscose rayon plant.

OBJECTIVE: This study investigated electrocardiography (ECG) manifestations for male workers with carbon disulfide exposure at rayon manufacturing plants. METHODS: A total of 251 men in the exposure group and 226 administrative clerks in the reference group received physical examinations and completed questionnaires. RESULTS: The prevalence of ECG abnormalities was much higher in the carbon disulfide exposure group (25.9%, n = 65) than in the reference group (2.7%, n = 6), with an odds ratio (OR) of 12.8 (95% confidence interval [CI] = 5.4-30.2). The foremen were at the highest risk of abnormal ECG (OR = 20.6, 95% CI = 6.5-65.2), followed by filament-spinning workers (OR = 14.2, 95% CI = 5.7-35.3), viscose-manufacturing workers (OR = 11.3, 95% CI = 4.3-30.1), and carbon disulfide-manufacturing workers (OR = 8.1, 95% CI = 2.7-25.6). The multivariate logistic regression analysis based on cumulative exposure index also showed a dose-response relationship with the exposure, and the risk of ECG abnormality could be initiated at the exposure history of 31 to 57 year-ppm with an OR of 7.2 (95% CI = 1.5-36.7). CONCLUSIONS: In general, the ECG abnormalities observed in workers at the permissible exposure level of carbon disulfide implicate the importance of environmental control of the chemical and of workers' education in exposure prevention at work.

Human PCDD/PCDF levels near a pentachlorophenol contamination site in Tainan, Taiwan.

A pentachlorophenol (PCP) manufacturing plant in southern Taiwan discontinued production in 1989. The site of the abandoned plant was heavily contaminated by PCDD/PCDFs, impurities formed in the PCP production process. Serum samples collected from 27 residents living near the deserted plant were evaluated to determine whether this contamination had associated serum levels of PCDD/PCDFs in local residents. The average level of 17 tested congeners ranged from 556 to 5240 pg/g lipid (mean, 1670 pg/g lipid). The corresponding 2,3,7,8-TCDD toxicity equivalent quotient values calculated by international toxicity equivalent factors (I-TEFs) and those recommended by WHO (WHO-TEFs) were 47.2 pg I-TEQ/g lipid and 53.4 pg WHO-TEQ/g lipid, respectively. Levels in other parts of Taiwan typically range from 15 to 20 pg WHO-TEQ/g lipid; therefore, it is likely that the heavily contaminated plant site caused these unusually high serum levels. The average PCDD/PCDF levels of 29 fish-tissue and nine soil samples collected from the sea reservoir surrounding the abandoned PCP plant were also abnormally high: 8630 pg/g lipid (985 pg WHO-TEQ/g lipid) and 606000 pg/g-sample (922 pg WHO-TEQ/g-sample), respectively. Factor analysis indicated that the congener pattern of human serum samples collected from residents living near the abandoned PCP plant different from samples collected from other areas in Taiwan without known PCDD/PCDF pollution. Similar results were observed for the fish tissue and soil samples. The current study may have discovered a "hot spot" for elevated dioxin human exposure in Taiwan. The preliminary finding has raised a public health concern in the inspected area and requires further investigations to clarify the nature of the contamination and potential impact on the local environment and human health.