THE PAIRED CASE-CONTROL STUDY BETWEEN AR IN ADULTS AND INDOOR POLLUTANTS

THE PAIRED CASE-CONTROL STUDY BETWEEN AR IN ADULTS AND INDOOR POLLUTANTS Weiwei YU, and Xiaochuan PAN Department of Occupation and Environmental Health, Peking University School of Public Health, Beijing, 100083, China ABSTRACT Background Allergic rhinitis (AR) is a very common disease with an increasing prevalence to 10-20% over the last 40 years all over the world including developing countries like China. But the reasons have not yet been known clearly. In recent years, There is an overwhelming evidence that sensitization to indoor allergens is a major risk factor for the development of clinical atopic disease because many people spend much of their life indoors (Kaiser,-H-B., 2004). Objective to investigate the association between AR in adults and indoor pollutants: NO 2, PM 2.5, formaldehyde, and mould in air and dust mites in dust. Methods Using 1:1 paired matching case control study design, we recruited 100 pairs of adults AR patients and the relevant control from the E.N.T.department of Renmin Hospital of Peking university, and detected formaldehyde in their kitchens and bedrooms, dust mites and fungi in bedrooms, Nitrogen dioxide (NO 2 ) in kitchens.the results of detections and questionnaires were analyzed by signal and multiple conditional regression model of SAS8.2 software. Results From the study we can see that AR is significantly associated with bedroom formaldehyde (OR =1.41,95%CI:1.03-1.92),kitchen formaldehyde(or= 1.64,95%CI:1.10-2.44),total fungi(or= 1.53,95%CI:1.19-1.96) and Dp (OR=1.58,95%CI:1.12-2.24) among indoor air pollutants after adjusting for exposure to dusts,present smoking and family AR or asthma history. In addition, after ranking the concentration of air pollutants into 4 quarters, there was a definite dose-response relationship between adults AR and total fungi, formaldehyde and Dp. But only the fourth rank had significantly statistic difference between AR and bedroom formaldehyde(or=4.05, 95%CI : 1.42-11.54),kitchen formaldehyde(or= 31.94,95%CI:2.60-392.54),total fungi(or= 2.64,95%CI: 1.25-5.56) and Dp (OR= 2.44,95%CI:1.08-5.50) after being adjusted. Conclusions Adults with AR had a preferential sensitization to the total fungi, formaldehyde and Dp species. Furthermore there was a definite dose-response relationship between the adults AR and indoor air total fungi, formaldehyde and dust Dp exposure. KEYWORDS AR risk factors indoor activities case-control study INTRODUCTION AR is a common disease in clinic and has been and will be increasing in a long term. Since year 3000 BC, pollenology (science that studies allergens) was already known. In the year 49 BC, Herodotus recognized the first case of hay fever; Jacob Constant (17th century) described the first case of AR and related it to "something" (allergens) that roses emitted. Charles Backley (1873) proved the ability of the skin to determine allergic reactions to allergens. In recent years there are many theories to explain the Corresponding Author: Tel: +86-10-82802530(O) E-mail address: xcpan@bjmu.edu.cn

reasons including better diagnosis, urban living, and higher exposure to dust mites, atmospheric pollution, nutrition, lifestyle changes, maternal smoking, diesel fumes, geography, the "hygiene hypothesis," and several others. But until now nobody knows why with certainty. It has been known that environmental issues and lifestyle changes are becoming increasingly more important as significant risk factors. There is overwhelming evidence that sensitization to indoor allergens is a major risk factor for the development of clinical atopic disease, because many people spend much of their life indoors (Kaiser,-H-B., 2004). MATERIALS AND METHODS Case selection. Approved to be AR without asthma by the E.N.T. (Ear nose throat) department of Renmin Hospital of Peking university with SPT (Skin prick test) and others; the age should be more than eighteen years old; the consciousnesses were clear enough to response the questionnaire and approval of indoor detection. Control selection. Nonallergic disease patients that were diagnosed by the E.N.T.department of Renmin Hospital of Peking university; the age should be more than eighteen years old; the consciousnesses were clear enough to response the questionnaire and approval of indoor detection. Questionnaire. interviewed by face to face with designed epidemiological health questionnaire indoor air and health questionnaire, according to international study asthma and allergies in adults (ISAAA), consisted of 64 items, including general social demographic characters,disease history, smoking history, occupation, indoor environmental situation and genetic family history was administered by trained research assistants.

Indoor detection. We detected the formaldehyde in kitchens and bedrooms, dust mites in bedroom dust and airborne fungi in bedrooms, and NO2 in kitchens between July13 to July 24. All samples except dust mites which were vacuumed the dust at the time, needed 24 hours and were taken back at the same time of the next day. Temperature and relative humidity were recorded by Mannix digital thermo-hygrometer at the time of sampling. The test of the samples must be completed within one week after sampling. Formaldehyde. Formaldehyde was measured with a passive sampling badge, and placed in the bedrooms 1.2m above the floor for 24 hours and then analyzed by AHMT colorimetric method. NO 2. a passive NO2 sampling badge was placed in the bedrooms 1.2m above the floor for 24 hours and then analyzed by Saltzaman hydrochloric acid naphthalene ethylenediamine colorimetric method. Fungal airborne. A centrifugal type portable air sampler (#LWC-1, Byxy Manufacturing Co., Beijing) in combination with culture medium strips was used to collect fungal airborne propagules. The sampling period was 1 min, and two sampling sites in a bedroom is a diagonal. After then, the strips were incubated at 25 for 48 hours, after which the resulting colonies were counted. Fungi were identified to level genus and, if possible, to species level by colony structure or microscopic examination of the spore structure. Concentrations were reported as colony-forming units per cubic meter (CFU/m3) of air. Dust mites. The floor carpet, mattress, pillows, sofa in the Participators bedrooms were vacuumed for 5 min, using a German canister vacuum cleaner (#N-191, Solac Co, Germany). After sampling, the dust was sealed in a plastic bag and was taken back to the laboratory the same day and weighed. Then analyzed for allergen content with enzyme-linked immunosorbent assay (ELISA)for Df and Dp in the dust(half quantitative method). PM2.5. Twenty-four hour average PM2.5 mass concentrations were measured using single pore multiple-stage impactors (#224-PCXR8,SKC company, America). The concentrations were calculated with the mass difference after and before sampling. Statistical methods. The questionnaires were logged in and error was corrected with epidata3.2 software, and the detection data were inputted with Microsoft Excel 2002. We performed all statistical analyses using SAS statistical software (version 8.2, SAS Institute Inc., Cary, NC) and SPSS (version 10.0, Insightful Corporation, Seattle, WA) statistical package. Paired t test, correlation, multivariate liner regression, signal and multivariate conditional Logistic regression analysis were used to analyze the significance of the differences between two groups that may confound the relationship between the indoor pollutant levels and adults AR. RESULTS General condition. We tabulated the results according to table 1, Of the 100 pairs adults included in this analysis, male sex was 49 pairs, female sex was 51 pairs, the rate of sex is 0.96:1, age in case group was between 19 to 77 with mean 42.67±14.08; age in control group was between 18 to 81 with mean 42.78±14.14; There were no significantly statistic difference in education, nationality, marriage statement and occupation (P>0.05 respectively).

The compare of the indoor pollutants concentration in two groups From table 1, The concentration of the bedroom formaldehyde, kitchen formaldehyde, total fungi, Pen, Df, Dp in bedrooms were higher in case group than that in controls and the difference had statistical significance (P<0.05), while the concentration of Asp, PM 2.5 in bedrooms and NO 2 in kitchens had no statistical significance between the case and control groups (P>0.05). The relationship between indoor pollutants and AR According to 25%, 50%, and 75% and above 75 % of the concentration of different pollutants, we ranked 4 grades from lowest to highest with each pollutant. after ranking the indoor pollutants which had statistical significance for 4 grades, we can see that the concentration of bedroom and kitchen formaldehyde was higher in the last two ranks than the criterion of indoor air quality (<100ug/m 3 ).the concentration of bedroom and kitchen formaldehyde had no significant difference(p=0.86) after analyzed with paired t test,and also there were positive correlations between the kitchen and bedroom formaldehyde(r=0.20,p<0.01),between total fungi and Pen (r=0.56,p<0.05), between Df and Dp(r=0.60,p<0.05) (table 3). The dose response relationship between AR and indoor pollutants After ranking the concentration of air pollutants into 4 quarters, the other 3 quarters unadjusted OR values of formaldehyde in bedrooms, formaldehyde in kitchens, total fungi, Dp were increasing respectively comparing with the first quarter and after adjusting for exposure to dusts, present smoking and family AR or asthma history, the OR values of them were all increasing also. But only the fourth ranks of them except total fungi which both the unadjusted third and fourth ranks had significant differences between case and control groups both unadjusted and adjusted. Meanwhile, the total trend of OR value showed that the risk of the adults AR would be increased 1.48times (unadjusted) and 1.41 times (adjusted) with each quarter increasing of the bedroom formaldehyde concentration, and 1.58 times (unadjusted) and 1.64 times (adjusted) with each quarter increasing of the kitchen formaldehyde concentration, and 1.53 times (both unadjusted and adjusted) with each quarter increasing of the bedroom total fungi concentration, and 1.45times (unadjusted) and 1.58 times (adjusted) with each quarter increasing of the bedroom Dp(not shown). The risk of the adults AR would be increased 0.001 times and 0.006 times than before when the bedroom total fungi and Pen concentration increasing each 1cfu/ m 3, and 0.005 times with a increase in bedroom and 0.009 times with a increase in kitchen formaldehyde levels of 1µg/ m 3, after analyzing the values of different pollutants concentration with the conditional Logistic regression (not shown). Discussion This study showed that there was a close relationship between indoor pollutants and doctor-diagnosed AR in adults. Factors associated with an increased risk of AR included overall concentration of bedroom fungi and formaldehyde in bedrooms and kitchens, bedroom Dp after analyzing by paired t test, independent of exposure to dusts, present smoking and family AR or asthma history. Formaldehyde had correlation with AR, and children were more allergic (Tatsuo Sakamoto, Satoru Doi, et al.,1999,, M.H.Gartette.et al.,2000); In 27 medical students, a 10-week exposure to inhaled formaldehyde, specific IgE against formaldehyde were assessed, which seemed that formaldehyde could induce an IgE-mediated sensitization although not determined (F. Wantke, M. Focke,etal,2000). Furthermore there was a dose-response relationship between the adults AR and bedroom or kitchen formaldehyde. The risk was serious by the increase of the concentration of formaldehyde (M.H.Gartette.et al., 2000). In our study, the risk of formaldehyde in two groups had significant

difference only in the fourth rank (291.22 ug/m 3 in bedroom and 300.64ug/m3 in kitchen) (OR=4.05, 95%CI: 1.42-11.54, bedroom, OR=21.94, 95%CI: 2.60-392.54, kitchen) with the OR value increasing respectively comparing with the first quarter. Furthermore, the formaldehyde concentration increased 0.005 and 0.009 times specifically with an increase in bedroom and kitchen formaldehyde levels of 1µg/ m 3. Table 2 distribution of ranking the indoor pollutants Variables Rank N x ±s.d Range 1 54 26.48±11.35 0-40 2 52 61.92±10.67 50-80 Bedroom formaldehyde *a 3 45 128.67±24.46 90-170 4 48 291.22±110.32 180-690 Total 200 124.00±116.66 0-690 1 59 29.15±11.49 2 42 60.48±8.25 0-40 Kitchen formaldehyde *a 3 52 114.42±27.82 50-70 4 47 300.64±105.76 80-160 Total 200 122.00±8.29 170-590 1 49 190±101.57 0-325 2 49 477±91.45 350-625 Total fungi ** 3 52 813±101.21 638-975 4 50 1565±699.56 1000-375 Total 200 749±633.83 0-3750 1 52 0 0-0 2 47 25±7.36 12-38 Pen ** 3 41 58±11.28 50-75 4 60 211±187.08 88-1188 Total 200 70±121.29 0-1188 1 48 0.18±0.29-1.15-0.41 2 51 0.47±0.04 0.42-0.53 Df *** Dp *** 3 52 0.66±0.09 0.54-0.82 4 49 1.03±0.19 0.83-1.64 Total 200 0.59±0.35-1.15-1.64 1 50-0.56±1.26-6.65-0.38 2 51 0.58±0.09 0.40-0.72 3 49 0.83±0.06 0.73-0.91 4 50 1.11±0.17 0.92-1.60 Total 200 0.49±0.89-6.65-1.60 a: bedroom and kitchen formaldehyde paired t test p value=0.86. *: r=0.20,p<0.05,the correlation between the kitchen and bedroom formaldehyde. **: r=0.56,p<0.05,the correlation between fungi and Pen. ***: r=0.60,p<0.05,the correlation between Df and Dp.

Table 3 the correlation between indoor pollutants and adults AR Pollutants rank AR Number Yes No Unadjusted OR 95% CI Adjusted# OR 95% CI 1 20 34 1.00 1.00 2 25 27 1.07(0.64-2.45) 1.05(0.34-2.65) Bedroom 3 19 26 1.37(0.46-2.97) 1.74(0.67-4.48) formaldehyde 4 35 13 4.36(1.82-10.44)** 4.05(1.42-11.54)** Trend 1.48(1.14-1.91)** 1.41(1.03-1.92)* 1 26 33 1.00 1.00 2 18 24 1.00(0.44-2.24) 1.11(0.48-3.56) Kitchen 3 22 30 1.14(0.52-2.48) 1.18(0.46-2.98) formaldehyde 4 34 13 12.24(2.65-56.62)** 31.94(2.60-392.54)** Trend 1.58 (1.15-2.16) ** 1.64(1.10-2.44) ** 1 18 39 1.00 1.00 2 20 24 1.81(0.80-4.08) 0.91(0.29-2.82) Total fungi 3 28 21 2.80(1.29-6.06)* 1.99(0.77-5.14) 4 34 16 5.17(2.20-12.15)** 2.64 (1.25-5.56)* Trend 1.53 (1.19-1.96)** 1.53(1.13-2.09)** 1 21 31 1.00 1.00 2 24 31 1.15(0.51-2.58) 0.61(0.22-1.71) Pen 3 23 23 1.20(0.58-2.46) 1.13(0.62-3.88) 4 32 15 1.95(1.07-3.58)* 1.79(0.86-3.74) Trend 1.30 (1.03-1.63)* 1.18(0.90-1.55) 1 23 31 1.00 1.00 2 23 25 1.33(0.56-3.15) 1.27(0.44-3.68) Df 3 23 26 1.03(0.50-2.12) 1.60(0.64-3.99) 4 31 18 1.98(1.02-3.87)* 1.43(0.62-3.30) Trend 1.28(0.99-1.65) 1.25(0.90-1.75) 1 21 30 1.00 1.00 2 21 30 1.06(0.44-2.55) 1.22(0.40-3.69) Dp 3 28 23 1.85(0.64-3.62) 2.40(0.92-6.24) 4 30 17 2.23(1.14-4.38)* 2.44(1.08-5.50) * Trend 23 31 1.45(1.10-1.91) * 1.58(1.12-2.24) * *: p<0.05, **: p<0.01 #: Adjusted for exposure to dusts, present smoking and family AR or asthma history There is a large literature demonstrating the relationship between fungal sensitization and AR, as well as a growing literature linking fungal exposure to rhinitis exacerbation (Downs SH, Mitakakis TZ,2001, Halonen M, Stern DA,1997). Other studies also found associations between measures of total fungi and health outcomes (Gent JF, Ren P,2002). The fact that fungal exposure in sensitized individuals may result in histamine and IgE-mediated nasal inflammation (Skoner DP,2001).

(1 3)-D-Glucans-glucose polymers that are structural components of most fungal cell walls-are known to stimulate macrophages and neutrophils (Chew GL, Douwes J,2001, Beijer L, Thorn J,2002). It also indicated in our study that only in a certain high concentration with the mean of 1565 cfu/m 3 (1000 cfu/m 3-3750 cfu/m 3 ) of total fungi could result in AR incidence or exacerbation. Also, the risk of the adults AR would be increased 0.001 times and 0.005 times than before when the bedroom total fungi and Pen concentration increasing each 1cfu/ m 3. The allergen of dust mites is a kind of protein enzyme secreted from dust mites enteron which augments the penetration of the respiration cells and stimulates the immune system to engender allergic reaction, so that results in the inflammation of the nasal mucous membrane (Li Jianlin et al.,2005). Sun Zhenfeng et al. found that Skin prick test (SPT) result was positive for traditional house dust mites (Dp and Df mix) in 85% of patients of allergic rhinitis both in children and adults groups (Sun Zhenfeng, Meng Qinghong, et al, 2003). In addition, there was a definite dose-response relationship between the adults AR and indoor dust Dp, and the OR value had the significant difference when the mean of concentration was more than 1.11 (0.92-1.60)*100 IU/ml. The risk of the adults AR would be 2.44 times comparing with the first rank. Potential study limitations Using 1:1 paired case-control design added the reliability between two groups and the statistic efficiency was enhanced when age and sex were well matched. Furthermore a large sample size (100 pairs) could be better to reflect the general level of indoor pollution in Beijing, while this study does have some limitations. Potential limitations of our work include the indoor pollutants exposure is relatively complex, along with the multiplicity of variables being considered. Our use of the questionnaire and detection altogether approach provides an efficient and appealing method for handling multiplicity issues. Even so, the reality is that some important differences may have been missed. In addition, the air and dust samples were single, short-term samples. Therefore, it is not clear how representative the samples are of long-term household indoor pollutant levels. REFERENCES Beijer L, Thorn J, Rylander R. 2002. Effects after inhalation of(1 3)-β-D-glucan and relation to mould exposure in the home. Mediators Inflamm 11(3):149 153. Chew GL, Douwes J, Doekes G, Higgins KM, Spithoven J, van Strien R et al. 2001.Fungal extracellular polysaccharides,and β (1 3) glucans, and culturable fungi in repeated sampling of house dust. Indoor Air 11(3):171 178. Downs SH, Mitakakis TZ, Marks GB, Car NG, Belousova EG, Leuppi JD, et al. 2001. Clinical importance of Alternaria exposure in children. Am J Respir Crit Care Med 164(3): 455 459. F. Wantke, M. Focke, W. Hemmer, et,al. Exposure to formaldehyde and phenol during an anatomy dissecting course: sensitizing potency of formaldehyde in medical students. Allergy 2000: 55: 84-87. Gent JF, Ren P, Belanger K, Triche E, Bracken MB, Holford TR,et al. 2002. Levels of household mold associated with respiratory symptoms in the first year of life in a cohort at risk for asthma. Environ Health Perspect 110:A781 A786.

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