Indian J Physiol Pharmacol 2001; 45 (2): 215-221

PULMONARY FUNCTIONS IN WORKERS OF FERTILISERAND CHEMICAL INDUSTRY

B. GEETHA*, R. HARIKUMARAN NAIR, C. KESAVACHANDRAN,SUSAN CHANDY AND S. SHASHIDHAR**

Physiological Chemistry Research Laboratory,School of Biosciences, Mahatma Gandhi University,Kottayam - 686 560

( Received on April 13, 2000)

Abstract : The present study was undertaken to assess the pulmonaryfunctions in fertiliser and chemical industry workers of Kerala. Pulmonaryfunction test was performed with Vitalograph Compact-II spirometer.Exposure to different chemicals, noxious gases and particulate matter offertiliser and chemical industry was injurious to the normal pulmonaryfunction. Significant decline in lung volumes, viz. FVC, FEV l' FEV I/FVC%(P<O.OI) and flow rates, viz. FEF25_75%, FEFO.2_1.2' FEF25%, FEF50%,FEF 75% (P<O.Ol) among non-smokers and smokers than that of normalcontrols was observed. The findings of this study also suggest that withincreased duration of exposure to industrial pollutants, lung volumes andflow rates were significantly reduced in workers.

Key words: pollution flow ratefertiliser and chemical industry

INTRODUCTION

Industrial workers are generally at riskdue to constant exposure to different typesof pollutants emitted from the industries.Inhalation of these substances can causedamage to the membrane structure andmechanical efficiency. This will lead toalteration in the functional properties of thelungs, resulting various respiratorydiseases. Duration of exposure, ageing andsmoking can together complicate pulmonaryfunctions. Pulmonary function tests give aclear idea about the condition of pulmonarydysfunction.

pulmonary functionlung volume

The different plants in fertiliser andchemical industry include ammonia plant,urea plant, sulphuric acid plant, phosphoricacid plant, NPK plant etc. where variouschemical processes involving high pressureand temperature are needed. Various rawmaterials and chemicals of hazardous natureare needed for the production of chemicalsincluding fertilisers, viz. ammonia, urea,phosphoric acid, sulphuric acid, ammoniumsulphate, NPK, gypsum by-products,ammonium chloride, super phosphate,ammonium phosphate etc. The presence ofsulphur dust, gaseous effluents, chemicalsand other air-borne contaminants in the

*Corresponding Author

216 Geetha et al

factory is absorbed high in the airway,increasing the airway resistance therebyadversely affecting the pulmonary functionsof workers. Hence this study wasundertaken with a view to analyse therespiratory status of fertiliser and chemicalindustry workers of Kerala.

METHODS

A total of 175 male workers fromFertilisers and Chemicals Travancore Ltd.(FACT), Udyogamandal Division, ErnakulamDistrict, Kerala were selected for the study.In each case, age of the subject, smokinghabits, type of work, duration of exposure,type of irritants, physical status and healthconditions were recorded throughquestionnaire. Subjects with less exposureperiod were excluded from the study. Theclinical data were collected from workersand respiratory function test were carriedout in the health centres of respectivefactory in the presence of medical officers.Same procedure was carried out for controlsalso. Sixty-one age group matched non-smoking normal male controls were selectedfrom non-industrial area who were supposedto have never exposed to any industrialpollutants.

Pulmonary functions were measuredwith a portable PC based spirometerwith printer (Vitalograph Compact-II,Buckingham). According to ATSrecommendations (1987), spirometry wasperformed during morning hours in aclimate-controlled room in a clean area ofthe industry. Spirometer was calibrated withtwice daily by pumping 5 litre of air throughthe instrument with 1 litre precisionsyringe. After calibration of the machine,

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the procedure of pulmonary tests wascarefully explained to each group of subjectswho were then allowed to make trialmanoeuvres. Before the test, the subjectswere given full physical and mentalrest. They were made 3-5 efforts whilestanding and wearing a nose clip. The bestof the multiple trials was recordedautomatically by the spirometer at BTPS(body temperature, ambient pressure andsaturated with water vapour).

Parameters studied

Lung volumes: Forced vital capacity (FVC),Forced expiratory volume at 1 second(FEV 1)' ratios between forced expiratoryvolume in 1 second to forced vital capacity(FEV /FVC%).

Flow rates: Forced mid expiratory flow rate(FEF25-75%), Mean forced expiratory flowrate at 0.2 to 1.2 litres (FEFO.2_1.2), forcedexpiratory flow rate at 25%, 50% and 75%of FVC (FEF25%, FEF50%, FEF75%).

Data analysis: Statistical analysis of resultswere carried out using unpaired 't'-test. (i)To test the significance of lung volumes andflow rates between normal controls vs.smokers, normal controls vs. non-smokersand smokers vs. non-smokers. (ii) To explorethe relationship between exposure durationand respiratory parameters, coefficient ofcorrelation was carried out and it was testedfor significance.

RESULTS

The mean duration of exposurewas 21.06 years. Among 175 workers 39.4%

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(n = 69) were non-smokers, 60.6% (n = 106)were smokers.

Smokers and non-smokers showedsignificant decrease in the values of FVCand FEV 1 (P<O.Ol) from that of normalcontrols in all age groups. The FEV 1/FVC%was also showed decrease in two age groups,i.e. G2 and G3 in case of smokers and non-smokers (P<O.Ol) than normal controlsbut the decrease was insignificant betweenG1 normal controls and smokers.

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Highly significant decline in flow rates, viz.FEF25_75%, FEFO.2-1.2' FEF25%, FEF50%and FEF75% (P<O.Ol) was observed in allage groups of smokers and non-smokersthan that of normal controls. FVC ofsmokers had significant decrease in G1(P<O.Ol) and FEV 1/FVC% in G2 (P<O.Ol)from non-smokers. But the ratio was higherin G1 smokers than non-smokers (P<O.Ol).However smokers and non-smokers of FACTdid not exhibit any significant difference inflow rates (Table D.

TABLE I: Pulmonary functions of normal control (C), non-smoker (NSW) and smoker(SW) workers under different age groups. (Mean ± SD and 'p' values).

FACT workers P<

Parameters Control NSW SW C Vs. C Vs. NSW(Units) (C) NSW SW Vs. SW

G1 3.40±0.39 2.17±0.74 2.16±0.63 0.01 0.01 0.01FVC (L) (23) (29) (29)

G2 3.88±0.68 2.36±0.57 2.24±0.60 0.01 0.01 NS(21) (10) (9)

G3 2.61±0.38 2.15±0.60 2.11±0.56 0.01 0.01 NS(17) (30) (68)

G1 2.90±0.38 1.85±1.02 1.99±0.67 0.01 0.01 NSFEV1 (L) G2 3.59 ±0.41 1.53±0.74 1.76±0.48 0.01 0.01 NS

G3 2.28±0.33 1.39±0.52 1.37±0.61 0.01 0.01 NS

FEV1/FVC% G1 95.27±9.94 61.10±19.25 73.60±23.41 0.01 NS 0.01G2 93.76±4.76 65.89±26.69 64.14±33.45 0.01 0.01 0.01G3 92.35±9.62 60.87±30.80 62.96±34.75 0.01 0.01 NS

G1 5.85±0.91 2.30±1.00 2.21±0.69 0.01 0.01 NSFEF 25-75% (LIs) G2 4.77±0.67 2.19±0.54 1.97±0.51 0.01 0.01 NS

G3 4.06±0.56 1.76±0.62 1.63±0.57 0.01 0.01 NS

G1 7.81±1.28 2.99±1.31 2.54±0.83 0.01 0.01 NSFEF 0.2-1.2% (LIs) G2 6.87±1.24 2.60±1.17 2.33±0.84 . 0.01 0.01 NS

G3 5.19±1.05 1.93±0.86 1.79±0.87 0.01 0.01 NS

G1 7.92±1.24 2.57±1.88 2.69±1.08 0.01 0.01 NSFEF 25% (LIs) G2 6.99±1.09 2.45±1.44 2.06±1.29 0.01 0.01 NS

G3 5.89±1.15 1.84±1.12 1.75±1.22 0.01 0.01 NS

G1 5.78±1.04 1.93±1.46 2.42±1.16 0.01 .0.01 NSFEF 50% (LIs) G2 5.34±0.70 2.13±1.06 1.78±1.02 0.01 0.01 NS

G3 4.38±0.70 1.58±0.91 1.48±0.92 0.01 0.01 NS

G1 3.80±1.04 1.21±0.81 1.53±0.68 0.01 0.01 NSFEF 75% (LIs) G2 3.39±0.38 1.33±0.60 1.06±1.59 0.01 0.01 NS

G3 2.94±0.39 0.94±0.48 0.92±0.53 0.01 0.01 NS

G1<35 years; G2 35-45 years; G~'> 45 years; parenthesis indicate number of subjects; NS - not significant

218 Geetha et al

A significant negative correlationbetween exposure duration and pulmonaryfunctions was observed. With increase in theduration of exposure, lung volume, i.e. FEV1(P<O.Ol) and flow rates, viz. FEF25_75%(P<O.Ol), FEFO.2_1.2 (P<O.Ol); FEF25%(P<0.05), FEF50% (P<0.05) and FEF75%(P<O.Ol) were found to be significantlydecreased (Table II).

TABLE II: Correlation analysis of pulmonaryfunctions with exposure duration ofFACT workers.

Parameters Correlation coefficient(units) (n = 175)

FVC (L) -0.1175

FEV1 (L)

FEV1IFVC%

FEF25_75% (LIs)

FEF 0.2-1.2 (LIs)

FEF 25% (LIs)

FEF 50% (LIs)

FEF 75% (LIs)

-0.2635**

0.0754

-0.3130**.

-0.3657**

-0.2060*

-0.1913*

-0.2130**

*Significant for P<0.05; ** Significant for P<O.Ol

DISCUSSION

This study demonstrated that there issignificant decrease in lung volumes andflow rates in non-smoker and smokerworkers of FACT in comparison to normalcontrols. The difference between smokersand non-smokers was insignificant, thoughthe smokers deviate differently from non-smokers. Significant reduction in lungvolume and flow rates of smoker and non-smoker workers establish the fact thatchronic industrial exposure along with orwithout smoking is associated with small

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and large airway obstruction and restrictivecondition of lung. Workers employed inFACT are always exposed to a large varietyof gases, viz. CO2, CO, S02' chlorine,formaldehyde, ammonia, various oxides ofnitrogen, H2S, H2S04 and particular matterof varying size. Nitrous fumes cause suddenbronchospasm and death from respiratoryfailure at a concentration of 100-500 ppm.Irritation to upper respiratory tract alongwith severe alveolar oedema occurs as aresult of these fumes (2). These noxiousgases, along with dust particles getdeposited in the surfactant layer of alveoli,decrease the elastic recoil forces of the lung.Once the noxious gases enter the blood, theybind with haemoglobin or other bindingproteins. They are transported to thevarious parts of the body and exert theireffort on respiratory centres. These chemicalsubstances act directly or indirectly throughchemoreceptors of the sino-aortic mechanismresulting in respiratory distress leading toreduction in lung volumes and flow rates.It will be worth to note that in lowconcentrations these toxic substancescan stimulate or induce respirationthrough respiratory centres, but inhigher concentration they suppressrespiration (3).

The inhaled pollutants bring about thenarrowing of the airways followed byalteration in the mechanical properties ofthe alveolar walls leading to measurable lossof elastic recoil of lung and finally to theovert development of irreversible air flowlimitation (4). Airway pollutants such ascigarette smoke, inhaled dust and noxiousgases cause bronchoconstriction reflexlythrough stimulation of receptors in thetrachea and large bronchi (5). The elastic

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properties of the lung depend on thephysical characteristics of the lung tissueand the surface tension of the film liningthe alveolar wall. With the deposition ofpollutants on the alveolar wall andsurrounding bronchioles, elastic propertiesof the lungs are affected resulting in thereduction of lung volumes. The decrease inflow rates in the present work may be dueto the deposition of dust particles whichmight increase the inflammatory secretionof mucus which in turn results in increasein the airway resistance. This increase inthe airway resistance and mucus secretionsobstructs the breathing process. Results ofthe present study support the earlierobservation made by Astrand and Rodalh(6) that the constriction of bronchi resultsin decreased flow rates. The increase inresistance in upper and lower airwaysresults in reduction of PEF, FEF25-75%'FEF75-85% and FEFO.2-1.2 (7). Pollutantssuch as ammonia, nitrogen dioxide, sulphurdioxide and dust in fertiliser industry havebeen reported to reduce the lung volumessuch as FVC, FEV 1 and FEV I/FVC% andexpiratory flow rates of the workers (8).

Miller et al. (9) reported that reductionin FVC is not necessarily indicative ofrestriction caused by deposition of dusts butas a result of trapping of air. A reduction inFEV1 and flow rates is proportional to thereduction in FVC. Therefore, a reduction inFEV I/FVC% results in obstruction of airpassage. Present findings support the earlierobservations. Polyvinyl chloride (PVC)workers exposed to HCI, CO, CO2 andbenzene show acute and chronic obstructiveventilatory changes (10). The present workis in agreement with observation ofKolarzyk et al (11) that exposure to S02

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and NOx gases cause reduction in FEV 1 andFEF25_75%·

Joshi (8) was of opinion that reductionin FVC is largely due to the effect ofsmoking rather than exposure to industrialenvironment. Kreiss et al. (12) observed thatsmoking had a modifying effect on thepattern of respiratory function impairment.In the present study no significantdifference was observed between smokersand non-smokers in pulmonary functionsexcept FVC in GL' Similar observations werealso reported by Korn et al (13). It is clearfrom this that industrial dust exposure maybe associated with change in pulmonaryfunctions and smoking accentuates thesechanges.

Cigarette smoking and noxious gasestogether potentate each other diseases (14).Apart from the pollutants present inchemical factories, smoking producerestrictive and obstructive disturbances inventilation (15) while Gupta et al. (16) failedto find any link between respiratoryimpairment and duration of exposure withsmoking among industrial workers. In theSurgeon General's Report of 1985 from USPublic Health Service on Cancer andChronic Lung Disease in Work Place (17), itwas mentioned that interaction betweensmoking and the exposure is complex andneeds further development of techniques tostudy these interactions. The present studyalso highlights the above plea. The eviden ceof interaction between these two factors hasnot been consistent.

Mukhtar and Mohan Rao (18) were ofthe opinion that exposure to industrialatmosphere may lead to decrease in VC.

220 Geetha et al

Schwartz et al (19) reported a negativecorrelation between pleural thickening andFVC. Our observations suggest that lungvolumes and flow rates decrease withincrease in the duration of exposure toindustrial pollutants.

In conclusion, it seems that exposure todifferent chemicals, noxious gases andparticulate matter of FACT was injuriousto the normal pulmonary function.Significant decrease in lung volumes andflow rates among non-smokers and smokersthan that of normal controls was observed.But the difference between smokers andnon-smoker-s was insignificant. It was found

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that with increased duration of exposure totoxic pollutants, lung volumes and flowrates were significantly reduced in allworkers.

ACKNOWLEDGEMENTS

We express our obligation to themanagement of Fertilisers and ChemicalsTravancore Ltd., Udyogamandal Division,for granting. permission to carry out thestudy. We are also very grateful to thecontinuous voluntary participation of theemployees of FACT who contributed so muchto the successful completion of the study.

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