[The study on biological exposure index of occupational exposure to arsenic and its inorganic compounds].

Objective: To establish biological exposure index (BEI) of occupational exposure to arsenic and its inorganic compounds through occupational epidemiology and the regression analysis of internal and external exposure of workers. Methods: In November 2021, 125 workers with occupational exposure to arsenic and its inorganic compounds and 49 office administrators in a non-ferrous metal smelter in Yunnan Province were selected as the exposure group and control group, respectively. Air samples from the workplace of the study subjects on weekdays were collected and arsenic concentrations were determined. Urine samples were collected in end-of-work weekend and high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used to detect the levels of trivalent inorganic arsenic (iAs(3+)) , pentavalent inorganic arsenic (iAs(5+)) , monomethyl arsenic (MMA) and dimethyl arsenic (DMA) in urine. The correlations between arsenic concentration in the workplace air and arsenic species in urine of workers were analyzed. Arsenic exposure concentration and the level of urinary arsenic (ΣiAs+MMA+DMA) of workers was analyzed by linear regression and the BEI of arsenic and its inorganic compounds in the workplace was proposed based on the results of micronucleus test. Results: The median of time-weighted average concentration (C(TWA)) of arsenic in the workplace air of the exposure group was 0.0116 mg/m(3), and the over-standard rate was 71.2% (89/125) . The concentrations of iAs(3+), iAs(5+), inorganic arsenic (iAs=ΣiAs(3+)+iAs(5+)) 、MMA、DMA and urinary arsenic in the exposure group were higher than those in the control group at the end of shift, and the differences were statistically significant (P<0.05) . The concentration of arsenic in the workplace air had the strongest correlation with the concentration of urinary arsenic at the end of the shift (r(s)=0.909, P<0.001) . The regression equation was lg (y) =7.662+2.968lg (x) (r=0.821, P<0.05) . According to the occupational exposure limit (OEL) of arsenic in China, the concentration of urinary arsenic in the end-of-work weekend was calculated to be 53.2 µg/L. Combined with the results of micronucleus test, the BEI of occupational exposure to arsenic and its inorganic compounds in the workplace was proposed to be 50 µg/L. Conclusion: The urinary arsenic in the end-of-work weekend can be used as a biomarker of occupational exposure to arsenic, and its BEI is recommended to be 50 µg/L.

[The research progress of metabolism and occupational biological exposure index metabolism of inorganic arsenic and its compounds].

Arsenic is a common metal-like element. Drinking arsenic-containing water and occupational exposure to arsenic are the main ways exposure to arsenic for population. Long-term exposure to arsenic can cause various organs dysfunction and cancer. After entering the body, inorganic arsenic is mainly methylated into monomethyl arsenic and dimethyl arsenic in the liver. Only a small part of inorganic arsenic is metabolized in the kidneys and lungs, and finally the metabolites of arsenic are excreted in the urine. understanding the biological characteristics of arsenic absorption, metabolism, and distribution in the body and formulating biological indicators related to occupational exposure to arsenic and can provide a scientific basis for the prevention and treatment of arsenic-related diseases. This article will review the biological monitoring indicators of occupational exposure to arsenic and the metabolic process of arsenic in the body.

Effect of occupational exposure to lead on serum levels of lipid profile and liver enzymes: An occupational cohort study.

The present study was performed to know the effects of chronic lead exposure on serum lipids, lipoproteins, and liver enzymes in a cohort study among of lead mine workers. We followed of 200 Iranian workers for 3- years (2018-2020), 100 of them with known occupational exposure to lead thorough their work in lead mine while the others 100 were with no such exposure. Blood lead level (BLL), serum lipids, lipoproteins, and liver enzymes of the exposure group for 3- years were measured and compared with those attained in the non-exposed workers. The BLL levels of the lead-mine workers were higher than with recommended level and the non-exposed group (24.15 and 6.35 µg/dL, respectively). The findings indicated a positive and significant relationship between BLL and lactate dehydrogenase, aspartate transaminase, alkaline phosphatase, alanine transaminase, and bilirubin levels (P < 0.01). Also while we found a negative and significant correlation between BLL and triglyceride, total protein, albumin, and globulin levels (P < 0.01). This report depicted that chronic lead exposure is a risk factor for hematological, liver, and cardiovascular diseases. Despite the fact that the level of liver function parameters was in the normal range, the results of 3- years follow-up show a significant relationship between BLL and alteration of biochemical parameters levels.

Exposure to lead, mercury, styrene, and toluene and hearing impairment: evaluation of dose-response relationships, regulations, and controls.

The risk of hearing loss from exposure to ototoxic chemicals is not reflected in occupational exposure limits and most jurisdictions. The aims of this research were to investigate dose-response relationships between exposure to lead, mercury, toluene, and styrene and hearing impairment based on current epidemiological evidence, conduct cross-jurisdictional comparisons, and investigate control measures for exposure to ototoxic chemicals. Ovid Medline and Ovid Embase databases were used to find relevant publications. A total of 86 epidemiological studies met the eligibility criteria for final evaluation. When significant associations between exposure and outcome were identified, exposure levels were evaluated to determine whether No Observed Adverse Effect Level (NOAEL) and Lowest Observed Adverse Effect Level (LOAEL) could be identified. Cross-jurisdictional comparisons included the U.K., U.S., Canada, and Australia occupational health and safety legislations. The majority of lead (75%), styrene (74%), and toluene (77%) studies showed significantly increased risks of hearing loss from exposure to these substances, although numerous studies on toluene (70%) and styrene (16%) compared auditory function between "solvent mixture" or "noise and solvent mixture" exposed groups and controls and not necessarily on groups exposed to a single agent. Based on five studies, blood lead ranges of 1-1.99 µg/dL to 2.148-2.822 µg/dL were identified as NOAELs while blood lead levels of 2 µg/dL up to 2.823-26.507 µg/dL were identified as LOAELs for hearing loss. Except for general duty clauses, the U.S., Canadian, and Australian jurisdictions have set no enforceable regulations specific to ototoxic chemical exposures. A biological exposure index of 2 µg/dL is recommended for prevention of hearing impairment from lead exposure. Based on Safe Work Australia, noise exposure limits may be reduced to 80 dB(A) for 8 hr. Other recommendations include performing audiometric testing and controlling exposure through all routes of entry.

Health hazards of xylene: a literature review.

Xylene, an aromatic hydrocarbon is widely used in industry and medical laboratory as a solvent. It is a flammable liquid that requires utmost care during its usage. On exposure the vapours are rapidly absorbed through the lungs and the slowly through the skin. Prolonged exposure to xylene leads to significant amount of solvent accumulation in the adipose and muscle tissue. This article reviews the various acute and chronic health effects of xylene through various routes of exposure.

A Study on Urinary Excretion of o-Cresol and Hippuric Acid of Workers Daily Exposed to Toluene on Each Day of the Week / 항공우주의학회지

BACKGROUND: The purpose of this study is to find out the relationship between the airborne toluene concentrations and the daily urinary metabolites such as hippuric acid and o-cresol for a sequential 5 days and to provide the appropriate sampling time for a special physical examination in the workers exposed to toluene. METHODS: The volunteers of 36 workers in the shoe making company were selected to measure the concentrations of airborne toluene exposure and to sample the daily urines in pre and end-shift for sequential 5 days form Monday to Friday and to get self-administered questionnaire including the items such as job records, disease records, smoking, alcohol drinking, eating some foods containing benzoic acid before work. RESULTS: The geometric means of toluene concentrations showed 46.40 ppm as the lowest value on Monday and 62.31 ppm as the highest one on Thursday. But there is no significant difference between both of those. The concentrations of hippuric acid and o-cresol in urine sampled on end-shift were higher than that of the others and showed statistically significant differences on each day. The metabolites of toluene were not related with taking alcohol and some foods containing benzoic acid as a result of logistic regression. CONCLUSION: From the above results, it is suggested that the hippuric acid and o-cresol in urine be very useful for biological monitoring in the workers exposed to toluene. Moreover, the daily hippuric acid and o-cresol concentrations in urine are also important for toluene exposure assessment and the further study has to be conducted to find out the tendency of biological exposure indices for continuous toluene exposure.

Simultaneous analysis of urinary 2-thiothiazolidine-4-carboxylic acid and thiocarbamide as a biological exposure index for carbon disulfide exposure

The objectives of this study were to develop optimal analytic methods for detecting urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) and thiocarbamide simultaneously and to evaluate the usefulness of these metabolites to a biological exposure index (BEI) for carbon disulfide (CS2) exposure. For this experiment, synthesized TTCA and thiocarbamide were used. The synthesized TTCA was identified by infrared spectrophotometer, nuclear magnetic resonance spectrometer and thin layer chromatography. The recovery rates of both metabolites were calculated to find the optimum analytical method. The amounts of urinary TTCA and thiocarbamide were measured by using an ultraviolet detector connected to high performance liquid chromatography (HPLC) after the administration of CS2 (350, 700 mg/kg) into Sprague-Dawley rats intraperitoneally. The maximum absorbance wave lengths for TTCA and thiocarbamide were 272 and 236 nm, respectively. Ethyl acetate extraction with NaCl as a salting-out reagent was used as a simultaneous extraction method for these metabolites. HPLC conditions for these metabolites included using a NH2 column, 50 mM KH2PO4: acetonitrile (85:15) and pH 3. Excreted amounts of urinary TTCA and thiocarbamide were increased significantly following CS2 administration. TTCA, which was already adopted as a BEI for CS2 by the American Conference of Governmental Industrial Hygienists (ACGIH), seems to be a more useful BEI for CS2 exposure than thiocarbamide. However further studies are needed to increase analytical efficiency before thiocarbamide can be adopted as a BEI and to apply this analytic method for simultaneous analysis of these metabolites in workers exposed to CS2.

Effect of Aldehyde dehydrogenase2 (ALDH2) Genotypes in Urinary Hippuric Acid Excretion as a Biological Exposure Index of Toluene / 대한산업의학회지

We investigated toluene exposure level, urinary hippuric acid concentrations, subjective symptoms and genotype of ALDH2 DNA in 134 exposed workers and 53 nonexposed workers for evaluating the effect of ALDH2 polymorphism on toluene metabolism and urinary hippuric acid concentration as biological exposure indices (BEI) of toluene. The results were as follows; 1. The percentage of inactive genotype of ALDH2 in exposed workers was lower than that of exposed (P=0.081). 2. The percentages of exposed workers with inactive genotype did not have any significant difference by the increase of toluene exposure level or work duration. 3. The frequency of drinking, monthly and maximum amount of alcohol intake in workers with normal genotype were significantly higher than those with inactive genotype. 4. The urinary hippuric acid concentration of nonexposed workers ,with inactive genotype was significantly lower than that with normal genotype. Under 100 ppm of toluene, similar but statistically insignificant trends were found, while above that concentration of toluene, reverse but statistically insignificant trends were found. 5. The number of acute and chronic subjective symptoms were increased positively with the concentration of toluene in workers with normal genotype, but ho such trends were found in workers with inactive genotype. 6. The result of simple linear regression between toluene and urinary hippuric acid concentrations showed a very significant positive linear relation-ship. The mean hippuric acid concentration of nonoccupational exposure was 0.289+/-0.227 (0.062-0.516) g/l. Toluene exposure level unable to discriminate with nonoccupational exposure estimated from regression equation, it range from 7.29 to 9.87 ppm. Considering above all things, it was useful to estimate the exposure level of toluene by means of analysing urinary hippuric acid concentration in both genotype workers, but the biological exposure indices (BEI) of both genotypes were different from each other. The BEI of the total exposed workers was 2.76 g/ I, which was lower than current criteria 3.0g/ I (2.5 g/g Cr), and it also suggest that the BEI for the exposed workers in our country be lowered to the appropriate level after further study.