Hydrazine. Determination in workplace air with high performance liquid chromatography – spectrophotometric technique

2019 ◽  
Vol 35 (1(99)) ◽  
pp. 45-57
Author(s):  
Marzena Bonczarowska ◽  
Patryk Piątek ◽  
Sławomir Brzeźnicki
Keyword(s):  
Limit Of Detection ◽  
Skin Irritation ◽  
International Agency ◽  
Dihydrogen Phosphate ◽  
Acid Extraction ◽  
Sodium Dihydrogen Phosphate ◽  
Limit Of Quantification ◽  
Liquid Chromatograph ◽  
Workplace Air

Anhydrous hydrazine in room temperature is colorless fuming oily liquid with ammonia-like odor. It is used in various industries for electrolytic plating of metals on glass and plastics, as a chemical intermediate for the synthesis of pesticides, insecticides, medicines and days. It is used also as water treatment agent in energy industry (corrosion inhibitor), rocket propellant and as explosives material. Long term exposure to hydrazine may cause to skin irritation and allergic reactions. Diluted aqueous solutions of hydrazine may be irritating for skin, eye and respiratory tract. Epidemiologic studies shows that chronic exposure to hydrazine may cause cancer. In European Union hydrazine is classified as a carcinogenic substance (cat. 1B). Experts from International Agency for Research on Cancer (IARC) have classified hydrazine as a compound probably carcinogenic to humans (Group 2A). Due to decreasing of MAC value for hydrazine in Poland it was necessary to develop and validate a sensitive method for determining hydrazine concentrations in the workplace air in the range from 1/10 to 2 MAC values, in accordance with the requirements of Standard No. PN-EN 482. The study was performed using a liquid chromatograph with spectrophotometric detection. All chromatographic analysis were performed with Discovery LC-18 150 × 2,1 mm analytical column, which was eluted with mixture of acetonitrile and water (6:4 v/v). The method is based on the collection of hydrazine on glass fiber filter impregnated with sulfuric acid, extraction with mixture of sodium dihydrogen phosphate and EDTA, derivatization of extracted compound with benzaldehyde and chromatographic determination of resulted solution with HPLC technique. The method is linear (r = 0.9989) within the investigated working range 0.15–3.5 μg/ml (0.00125–0.029 mg/m3 for a 240-L air sample). Calculated limit of detection (LOD) and limit of quantification (LOQ) were 0.0007 μg/ml and 0.0023 μg/ml, respectively. The average extraction efficiency of hydrazine from filters was 97% and samples stored in refrigerator are stable for 14 days. The analytical method described in this paper enables determination of hydrazine in workplace air. The method is precise, accurate and it meets the criteria for procedures for measuring chemical agents listed in Standard No. PN-EN 482. The method can be used for assessing occupational exposure to hydrazine and associated risk to workers’ health. The developed method of determining hydrazine has been recorded as an analytical procedure (see appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Ethylenediamine. Determination in workplace air with high performance liquid chromatography – spectrophotometric technique

2019 ◽  
Vol 35 (1(99)) ◽  
pp. 61-76
Author(s):  
Marek Zieliński ◽  
Ewa Twardowska ◽  
Małgorzata Kucharska
Keyword(s):  
Occupational Exposure ◽  
Silica Gel ◽  
High Performance ◽  
Limit Of Detection ◽  
Acid Extraction ◽  
Upper Respiratory Tract ◽  
Limit Of Quantification ◽  
Liquid Chromatograph ◽  
Workplace Air

Ethylenediamine (EDA) is a colorless, viscous liquid with ammonia-like odor. It is used as an intermediate in manufacture of chelating agents (EDTA), fungicide, poliamide and formaldehyde-urea resins, surfactants, corrosion inhibitors, emulsifying agents and stabiliser of rubber products. EDA may cause irritation of upper respiratory tract, eye and skin. Occupational exposure to EDA may lead to alergic reactions and asthma. EDA is not classified as carcinogennic to humans. The aim of this study was to develop and validate a sensitive method for determining hydrazine concentrations in the workplace air in the range from 1/10 to 2 MAC values, in accordance with the requirements of Standard No. PN-EN 482. The study was performed using a liquid chromatograph with spectrophotometric detection. All chromatographic analysis were performed with Supelcosil LC-18 (150 × 3 mm, 5 µm) analytical column, which was eluted with mixture of acetonitrile and water (6:4 v/v). The method is based on the collection of EDA on silica gel impregnated with sulfuric acid, extraction with mixture of acetonitrile and water (62:38 v/v), derivatization of extracted compound with 9-fluorenylmethyl chloroformate and chromatographic determination of resulted solution with HPLC technique. The method is linear (r = 0.9994) within the investigated working range 0.1–2 μg/ml (2–40 mg/m3 for a 10-L air sample). Calculated limit of detection (LOD) and limit of quantification (LOQ) were 0.04 μg/ml and 0.13 μg/ml, respectively. The average extraction efficiency of EDA from silica gel was 86% and samples stored in refrigerator are stable for 10 days. The analytical method described in this paper enables determination of EDA in workplace air. The method is precise, accurate and it meets the criteria for procedures for measuring chemical agents listed in Standard No. PN-EN 482. The method can be used for assessing occupational exposure to EDA and associated risk to workers’ health. The developed method of determining EDA has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Chlorobenzene. Determination in workplace air

2019 ◽  
Vol 35 (1(99)) ◽  
pp. 19-28
Author(s):  
Anna Jeżewska ◽  
Agnieszka Woźnica
Keyword(s):  
Occupational Exposure ◽  
Carbon Disulfide ◽  
Limit Of Detection ◽  
Skin Irritation ◽  
Raw Material ◽  
Good Precision ◽  
Limit Of Quantification ◽  
Selective Determination ◽  
Workplace Air

Chlorobenzene is a colorless, flammable liquid that has an almond-like odor. It is used in industry as a solvent: resins, paints and fats, raw material for the production of plastics, as well as for the production of phenol, aniline and nitrobenzene. Occupational exposure to chlorobenzene vapors can occur through inhalation, absorption through the skin or ingestion. Harmful if inhaled, causes skin irritation. Long-term exposure affects the central nervous system. The aim of this study was an amendment to the PN-Z-04022- 03:2001 withdrawn from the Polish set of standards, and validate method for determination concentrations of chlorobenzene in the workplace air in the range from 1/10 to 2 MAC values, in accordance with the requirements of the standard PN-EN 482. The study was performed using a gas chromatograph (GC) with a flame ionization detector (FID) equipped with a capillary column HP-5 (30 m x 0.32 mm, 0.25 μm). This method is based on the adsorption of chlorobenzene vapors on activated charcoal, desorption with carbon disulfide, and analyzed by GC-FID. Application of HP-5 column allows selective determination of chlorobenzene in a presence of carbon disulfide, aniline, phenol and nitrobenzene. The measurement range was 2.3 ÷ 46 mg/m3 for a 15 l air sample. Limit of detection: 6.75 ng/ml and limit of quantification: 20.25 ng/ml. Analytical method described in this paper enables selective determination of chlorobenzene in workplace atmosphere in presence of other solvents at concentrations from 2.3 mg/m3 (1/10 MAC value). The method is characterized by good precision and accuracy and meets the criteria for the performance of procedures for the measurement of chemical agents, listed in EN 482. The method may be used for the assessment of occupational exposure to chlorobenzene and the associated risk to workers’ health. The developed method of determining chlorobenzene has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Pentachlorophenol. Determination in workplace air by means of high performance liquid chromatography

2019 ◽  
Vol 35 (1(99)) ◽  
pp. 59-74
Author(s):  
Sławomir Brzeźnicki ◽  
Marzena Bonczarowska
Keyword(s):  
Occupational Exposure ◽  
Phosphoric Acid ◽  
Limit Of Detection ◽  
Crystalline Solid ◽  
Respiratory Disorder ◽  
Upper Respiratory Tract ◽  
Limit Of Quantification ◽  
Liquid Chromatograph ◽  
Workplace Air

Pentachlorophenol (PCF) in room temperature is a crystalline solid with phenol-like odor. It is soluble in most organic solvents (diethyl ether, acetone, carbon tetrachloride, methanol). It is slightly soluble in water. Pentachlorophenol is used as a fungicide, insecticide and as non-selective herbicide (defoliant) in cotton crops. It is also used as antimicrobial agent in leather, paper and textile industry. It has been widely used as wood preservative in wood and construction industry. Occupational exposure to pentachlorophenol may cause irritation of mucous membranes of the eyes and the upper respiratory tract and skin lesions. It may also lead to changes in the central nervous system like headache, insomnia, vertigo and depression. Acute poisoning may cause pulmonary edema, cardio-respiratory disorder and even death. Pentachlorophenol is also suspected to be carcinogenic to humans. The aim of this study was to develop and validate a sensitive method for determining pentachlorophenol concentrations in workplace air in the range from 1/10 to 2 MAC values, in accordance with the requirements of Standard No. PN-EN 482. The study was performed using a liquid chromatograph with spectrophotometric detection. All chromatographic analysis were performed with Zorbax SB-CN 250 × 4.6 mm analytical column, which was eluted with mixture of 0.1% phosphoric acid in acetonitrile and 0.1% phosphoric acid in water (6: 4 v/v). The method is based on the collection of pentachlorophenol on XAD 7 resin preceded by a glass fiber filter, extraction with methanol and chromatographic determination of resulted solution with HPLC technique. The method is linear (r = 0.9997) within the investigated working range 0.625–12.5 μg/ml (0.05–1.0 mg/m3 for a 25-L air sample). The calculated limit of detection (LOD) and limit of quantification (LOQ) were 0.014 μg/ml and 0.048 μg/ml, respectively. The average extraction efficiency of pentachlorophenol from filter and XAD 7 amounted to 95% and samples stored in refrigerator are stable for 14 days. The analytical method described in this paper enables determination of pentachlorophenol in workplace air. The method is precise, accurate and it meets the criteria for procedures for measuring chemical agents listed in Standard No. PN-EN 482. The method can be used for assessing occupational exposure to pentachlorophenol and associated risk to workers’ health. The developed method of determining pentachlorophenol has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

But-2-enal. Determination in workplace air

2019 ◽  
Vol 35 (1(99)) ◽  
pp. 5-18
Author(s):  
Anna Jeżewska ◽  
Agnieszka Woźnica
Keyword(s):  
Limit Of Detection ◽  
Array Detector ◽  
Good Precision ◽  
European Standard ◽  
Limit Of Quantification ◽  
Liquid Chromatograph ◽  
Selective Determination ◽  
Validation Parameters ◽  
Workplace Air

But-2-enal (crotonaldehyde) is a colourless liquid with an unpleasant suffocating odour. But-2-enal occurs naturally in food. It is mainly used for the production of sorbic acid, a food preservative. But-2-enal is a very toxic, highly irritating and allergenic substance – it is suspected of causing genetic defects. The aim of the study was to develop a method for determination of but-2-enal, which will enable determination of concentrations of this substance in the workplace air in the range from 1/10 to 2 MAC values. The tests were performed using a liquid chromatograph (HPLC) with a diode array detector (DAD), equipped with an Ultra C18 column (250 x 4.6 mm; 5 μm). The method consists in retaining the but-2-enal on a silica gel coated with 2,4-dinitrophenylhydrazine. The sample is extracted with acetonitrile and analyzed by HPLC. Validation of the method was carried out in accordance with the requirements of the European standard EN 482. The measuring range of the method is from 0.1 to 2 mg/m3 for a 12 l sample of air. The following validation parameters were obtained: limit of detection: 1.26 ng/ml (0.21 μg/m3), limit of quantification: 3.77 ng/ml (0.63 μg/m3), the overall accuracy of the method: 5.08%, expanded uncertainty: 22%. The developed analytical method enables selective determination of but-2-enal in workplace air at concentrations ranging from 0.1 mg/m3, i.e. from 1/10 of the MAC value in the presence of co-occurring substances. The method is characterized by good precision and accuracy and meets the requirements of the European standard PN-EN 482 for procedures for determination of chemical agents. The developed method of determining but-2-enal has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

STABILITY INDICATING UPLC METHOD FOR ESTIMATION OF METFORMIN HYDROCHLORIDE AND NATEGLINIDE SIMULTANEOUSLY IN THE PRESENCE OF STRESS DEGRADATION PRODUCTS

INDIAN DRUGS ◽  
2020 ◽  
Vol 57 (05) ◽  
pp. 56-64
Author(s):  
Rani A Prameela ◽  
S. Madhavi ◽  
Rao B. Tirumaleswara ◽  
Sudheer Reddy CH.
Keyword(s):  
Limit Of Detection ◽  
Degradation Products ◽  
Potassium Dihydrogen Phosphate ◽  
Metformin Hydrochloride ◽  
Forced Degradation ◽  
Dihydrogen Phosphate ◽  
Limit Of Quantification ◽  
Pharmaceutical Dosage Forms ◽  
Column Temperature

A novel Ultra Performance Liquid Chromatography (UPLC) method was developed and validated for the simultaneous determination of antidiabetic drugs metformin hydrochloride and nateglinide. The method was developed using a Waters ACQUITY UPLC SB C18 (100 × 2.1 mm, 1.8 μm) column. The mobile phase consisting of 0.01 % potassium dihydrogen phosphate buffer (pH 5.8): acetonitrile (50: 50 V/V) was used throughout the analysis. The flow rate was 0.3 mL/min, the injection volume was 1.0 μL, column temperature was 30 0C, run time 3 min and detection was carried at 238 nm using a TUV detector. The retention times of metformin hydrochloride and nateglinide were found to be 1.28 1.71 min, respectively. Metformin hydrochloride and nateglinide were found to be linear over the concentration range of 125-750 and 15-90 μg/mL. The limit of detection and the limit of quantification for metformin hydrochloride were found to be 0.22 and 0.68 μg/mL, respectively, and, for nateglinide, 0.02 and 0.6 μg/mL, respectively. Developed method was validated as per ICH guidelines. The specificity of the method was confirmed by forced degradation study. The suggested method is suitable for determination of metformin hydrochloride and nateglinide in bulk and pharmaceutical dosage forms.

scholarly journals A Stability Indicating UPLC Method for the Determination of Tramadol Hydrochloride: Application to Pharmaceutical Analysis

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Kanakapura B. Vinay ◽  
Hosakere D. Revanasiddappa ◽  
Cijo M. Xavier ◽  
Pavagada J. Ramesh ◽  
Madihalli S. Raghu
Keyword(s):  
Limit Of Detection ◽  
Potassium Dihydrogen Phosphate ◽  
Reversed Phase ◽  
Forced Degradation ◽  
Dihydrogen Phosphate ◽  
Uv Detector ◽  
Limit Of Quantification ◽  
Tramadol Hydrochloride ◽  
Stability Indicating

The use of Ultra Performance Liquid Chromatography (UPLC), with a rapid 5-minute reversed phase isocratic separation on a 1.7 μm reversed-phase packing material to provide rapid ‘‘high throughput’’ support for tramadol hydrochloride (TMH) is demonstrated. A simple, precise and accurate stability-indicating isocratic UPLC method was developed for the determination of TMH in bulk drug and in its tablets. The method was developed using Waters Aquity BEH C18 column (100 mm × 2.1 mm, 1.7 μm) with mobile phase consisting of a mixture of potassium dihydrogen phosphate buffer of pH 2.8 and an equal volume of acetonitrile (60 : 40 v/v). The eluted compound was detected at 226 nm with a UV detector. The standard curve of mean peak area versus concentration showed an excellent linearity over a concentration range 0.5–300 μg mL−1 TMH with regression coefficient (r) value of 0.9999. The limit of detection (S/N =3) was 0.08 μg mL−1 and the limit of quantification (S/N =10) was 0.2 μg mL−1. Forced degradation of the bulk sample was conducted an accordance with the ICH guidelines. Acidic, basic, hydrolytic, oxidative, thermal and photolytic degradation were used to assess the stability indicating power of the method. TMH was found to degrade significantly in acidic, basic and oxidative stress conditions and stable in thermal, hydrolytic and photolytic conditions.

scholarly journals Determination of Propane-1,3-sultone in Workplace Air for Occupational Exposure Assessment

2020 ◽  
Vol 17 (4) ◽  
pp. 1414
Author(s):  
Anna Jeżewska
Keyword(s):  
Occupational Exposure ◽  
Limit Of Detection ◽  
Glass Tube ◽  
Gas Chromatograph ◽  
Measuring Range ◽  
Limit Of Quantification ◽  
Occupational Exposure Assessment ◽  
Workplace Air ◽  
Air Sample

Propane-1,3-sultone (PS) is an alkylating substance used in the production of polymers, fungicides, insecticides, dyes, and detergents. It is absorbed into the human body by inhalation, digestion, and through the skin; it is also a possible carcinogen. Occupational exposure to this substance may occur on industrial or laboratory contact. In Poland, the maximum allowable concentration (MAC) for PS in workplace air is 7 µg/m3. The paper presents a method for determination of PS in workplace air using a gas chromatograph coupled with a mass spectrometer (GC-MS). Air containing PS is passed through a glass tube containing a glass fiber filter and two layers of silica gel. The substance is washed with acetonitrile and the solution obtained analysed using GC-MS. The measuring range for an air sample of 360 L is 0.7 ÷ 14 µg/m3. The limit of detection (LOD) is 13 ng/m3, limit of quantification (LOQ) is 40 ng/m3.

1,2-Dichloroethane. Determination in workplace air

2018 ◽  
Vol 34 (2(96)) ◽  
pp. 133-143
Author(s):  
Agnieszka Woźnica
Keyword(s):  
Limit Of Detection ◽  
Flammable Liquid ◽  
Limit Of Quantification ◽  
Selective Determination ◽  
Flame Ionization ◽  
Chemical Agents ◽  
Workplace Air ◽  
Other Substances ◽  
Air Sample

1,2-Dichloroethane is a colorless, highly flammable liquid with a chloroform-like odor. This substance is used in industry as an intermediate in the production of vinyl chloride, but it is also used in the production of other chlorinated hydrocarbons. It is also used as a solvent. 1,2-Dichloroethane is carcinogenic for humans. The aim of this study was to develop a method for determining concentrations of 1,2-dichloroethane in the workplace air in the range from 1/10 to 2 MAC values (0.82–16.4 mg/m3). The study was performed using a gas chromatograph (GC) with a flame ionization detector (FID) equipped with a capillary column HP-1 (50 m x 0.32 mm; 0.3 μm). The method is based on the adsorption of 1,2-dichloroethane on activated charcoal, desorption of analyzed compound with carbon disulfide and analysis of obtained solution with GC-FID. The use of HP-1 column enabled selective determination of 1,2-dichloroethane in a presence of other substances. The average desorption coefficient of 1,2-dichloroethane from charcoal was 0.98. The method is linear (r = 0.9999) within the investigated working range from 9.84 to 196.8 μg/ml, which is equivalent to air concentrations from 0.82 to 16.4 mg/m3 for a 12-L air sample. The limit of detection (LOD) and limit of quantification (LOQ) were to 2.284 μg/ml and 6.85 μg/ml, respectively. The analytical method described in this paper enables selective determination of 1,2-dichloroethane in workplace air in presence of other substances at concentrations from 0.82 mg/m3 (1/10 MAC value). The method is precise, accurate and it meets the criteria for procedures for measuring chemical agents listed in Standard No. EN 482. The method can be used for assessing occupational exposure to 1,2-dichloroethane and associated risk to workers’ health. The developed method of determining 1,2-dichloroethane has been recorded as an analytical procedure (see appendix).

2,2-Bis(4-hydroxyphenyl)propane – inhalation fraction. Determination method in workplace air

2017 ◽  
Vol 33 (3(93)) ◽  
pp. 141-150
Author(s):  
Marzena Bonczarowska ◽  
Sławomir Brzeźnicki
Keyword(s):  
Flame Retardants ◽  
Limit Of Detection ◽  
Upper Respiratory Tract ◽  
Negative Effects ◽  
Limit Of Quantification ◽  
Liquid Chromatograph ◽  
Selective Determination ◽  
Human Fertility ◽  
Workplace Air ◽  
Air Sample

2,2-Bis(4-hydroxyphenyl)propane (bisphenol A BPA) is a substance in a form of a solid crystals or flakes with a mild phenolic odor. BPA is commonly used in the production of epoxide, polycarbonate or polysulfone resins, glues, breaks fluids or as a flame retardants and fungicides. Exposure to BPA can cause irritation of skin, BPA can also act as a nefro or hepatotoxic factor and upper respiratory tract or mucous membranes of the eye. BPA has a negative effects on human fertility. The aim of this study was to develop and validate a sensitive method for determining BPA concentrations in workplace air in the range from 1/10 to 2 MAC values, in accordance with the requirements of Standard No. PN-EN 482. The study was performed using a liquid chromatograph with spectrophotometric (UV-VIS) and spectrofluorimetric (FLD) detection. All chromatographic analyses were performed with Supelcosil LC 18 (150 × 3 mm) analytical column, which was eluted with mixture of acetonitrile and water (1:1). This method was based on collecting BPA on glass fiber filter, extracting with acetonitrile, and chromatographic determining resulted solution with HPLC technique. The average extraction efficiency of BPA from filters was 90%. The method was linear (r = 0.9996) within the investigated working range 0.125–5 mg/m3 for a 720-L air sample. The calculated limit of detection (LOD) and the limit of quantification (LOQ) was to 0.02 μg/ml (UV-VIS) and 0.013 μg/ml (FLD), and 0.068 μg/ml (UV-VIS) and 0.042 μg/ml (FLD), respectively. The analytical method described in this paper enables specific and selective determination of BPA in workplace air in presence of other compounds. The method is precise, accurate and it meets the criteria for measuring chemical agents listed in Standard No. PN-EN 482+A1:2016-01. The method can be used for assessing occupational exposure to BPA and associated risk to workers’ health. The developed method of determining BPA has been recorded as an analytical procedure (see appendix).

Calcium hydroxid. Determination in workplace air

2019 ◽  
Vol 36 (2(100)) ◽  
pp. 61-72
Author(s):  
Jolanta Surgiewicz
Keyword(s):  
Calcium Hydroxide ◽  
Limit Of Detection ◽  
Absorption Spectrometry ◽  
Good Precision ◽  
European Standard ◽  
Limit Of Quantification ◽  
Respirable Fraction ◽  
Air Volume ◽  
Workplace Air

Calcium hydroxide is a white color solid. It is used in construction, chemical industry, water purification and wastewater treatment, flue gas desulphurization. Calcium hydroxide causes serious damage to the eyes, irritates the skin and it can cause after-launch respiratory irritation. Maximum allowable concentration value (MAC) for calcium hydroxide in the work environment in Poland, for the inhalable and respirable fraction is 2 mg/m3 (STEL is 6 mg/m3) and 1 mg/m3 (STEL is 4 mg/m3), respectively. The aim of the study was to develop a method for determining the concentration of calcium hydroxide present in the inhalable and respirable fraction in the workplaces atmosphere, in the range from 1/10 to 2 MAC values in accordance with the requirements of European Standard PN-EN 482. The developed method is based on collecting, stopping calcium hydroxide (contained in the inhalable and the respirable fraction) on membrane filters, mineralizing filters with concentrated nitric acid and determining calcium of the resulted solution by atomic absorption spectrometry with atomization in acetylene-air flame (F-AAS). The described method allows the determination of calcium in workplace air concentrations in the range of 0.50–20.00 µg/ml. The calibration curve characterized by a high value of the correlation coefficient: R2 = 1.0000. The limit of detection (LOD) is 0.1 ng/ml and the limit of quantification (LOQ) is 0.3 ng/ml. The determined coefficient of recovery is 1.00. An analytical method allows the determination of the concentration of the calcium hydroxide present in the workplace air in the inhalable fraction in the concentration range of 0.10–4.11 mg/m3 (sample air volume 720 L) and in the reparable fraction in the concentration range 0.07–2.70 mg/m3 (for a sample air volume of 684 L), which represents 0.05–2.1 MAC value for the inhalable fraction and 0.07–2.7 MAC value for the respirable fraction. The method has good precision and accuracy and meets the requirements of European Standard PN-EN 482 for procedures for determining chemical agents. The method for determining calcium hydroxide has been recorded in the form of an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

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