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Dibutyl Phthalate an Emerging Contaminant in Water-Based Paints.

Introduction

Many articles have reported the presence of emerging compounds in consumer products such as phthalates, in the human and aquatic environments and wastewaters. Emerging pollutants are new chemicals without regulatory status and which impact on environment and human health are poorly understood (Lioy et al., 2015; USEPA, 2012).

Phthalates are produced in excess of million pounds per year (USEPA, 2012; EPA, 2006). Phthalates are used in several industrial and consumer products, basically as plasticizers (on Earth and NASEM, 2017; Lioy et al., 2015). They are released into the environment from different sources such as industrial releases, the disposal of productions, processing and industrial wastes, municipal wastes, sewage sludge and release from commodities containing phthalates Braun et al. (2013). The exact phthalate or combination of phthalates utilized in a specific product.s formulation relies upon the properties the phthalates impart as well as their cost. Many phthalates can doubtlessly result in excessive exposure, both exclusively and together with other phthalates (Wang et al., 2019; Lioy et al., 2015; USEPA, 2012; Swan, 2008). They can frequently substitute for each other in products. U.S. Environmental Protection Agency.s (EPA.s) cutting-edge management plan considered the toxicity of phthalates, their occurrence in the environment and their considerable use and human exposure on Earth and (NASEM, 2017; CDC, 2005). Eight phthalates were considered: dibutyl phthalate (DBP), di-isobutyl phthalate (DIBP), butyl benzyl phthalate (BBP), di-n-pentyl phthalate (DnPP), di (2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DnOP), di-isononyl phthalate (DINP), and di-isodecyl phthalate (DIDP), USEPA (2012). These phthalates shows adverse effects to aquatic organisms in ecotoxicity studies Oehlmann et al. (2009). Toxic effects were observed at environmentally relevant exposures at the low concentration that is, ng/L to [micro]g/L range Oehlmann et al. (2009). Phthalates exposures can occur from releases that result from the production, processing or industrial use as well as contamination to air, water, food and dust resulting from the use or disposal of commodities containing phthalates (Wang et al., 2019; Lioy et al., 2015; Russo et al., 2015; Shaikh et al., 2012). Exposure sources of phthalates in the order of prevalence is food, cosmetics, consumer products (other than toys) and toys (Zota et al., 2016; Serrano et al., 2014; Hubinger, 2010; HSDB, 2009; Koo and Lee, 2004).

Dibutyl phthalate (DBP) is one of the main sources of indoor semi-volatile organic compounds (SVOCs) and topmost persistent organic contaminants Wang et al. (2010). It is used as softener for better spreadability, flexibility, to retain scents and dispensability (Larsson et al., 2014; Chang et al., 2013; Green et al., 2005) as a solvent and fixative; a suspension agent; a lubricant for aerosol valves; an anti-foamer; a skin emollient, a plasticiser, fingernail elongators (extensions), in medical devices and textiles, as propellants, in food packaging, as dental materials, and in paper production (Wittassek et al., 2011; OSHA, 2009). However, in few illegal food industry applications, phthalates have been used as a low-fee alternative to update palm oil as a clouding agent added to juices, yogurt and drinks Chang et al. (2013). Dibutyl phthalate is one of the most popular phthalates used as clouding agent in drinks, which has been detected by the Taiwan Food and Drug Administration in 2011 (USEPA, 2012; HSDB, 2009).

Phthalates can be released from products and exposure may occur in humans through food, dust, air and direct use of personal care products (Janjua et al., 2008; Wittassek and Angerer, 2008; Wormuth et al., 2006). DBP is very stable and can enter to all primary environmental media. It causes the most lethally to terrestrial organisms, fish, and aquatic invertebrates Staples et al. (1997). Besides its role as endocrine disruptor, DBP has been shown to alter the expression of a number of genes, increased DNA damage in sperm, premature breast development, shortened pregnancy in women, and decrease in anogenital distance among male infants (Zare et al., 2018; Monneret, 2017; Swan et al., 2005; Duty et al., 2003; Colon et al. 2000). It exposure is of potential concern for children.s health Craig et al. (2013). The National Toxicology Program concluded that high levels of di-n-butyl phthalate, may adversely affect human reproduction or development (Monneret, 2017; Sedha et al., 2015; Lin et al., 2011; Jahnke et al., 2005; NTP, 2003). They have also been measured in foods, milk and drinking water. The relative contribution from the various sources and routes of exposure to phthalates is unknown (Schecter et al., 2013; Fierens et al., 2012; Cao, 2010; Kolarik et al., 2008; Wormuth et al., 2006). Despite the enormous health effects, there remain no regulations on DBP in water-based paints manufactured and marketed in Nigeria. The objective of this work was to identify and access the levels of dibutyl phthalate, an emerging contaminants in water-based paints and their associated health effects.

Materials and Methods

Paint sampling. Paint samples of different colours and 14 manufacturers were purchased in popular paint markets in Ibadan and Lagos, Nigeria. A total of 174 paint samples were collected. These samples were stored in air-tight plastic containers and analysed at the Council of Scientific and Industrial Research-National Environmental Engineering Research Institute Laboratory, Nagpur-Maharashtra, India (Idayat Apanpa-Qasim and Adeyi, 2018).

Samples pre-treatment and analysis. Approximately 2.5 mL paint samples were carefully measured into 50 mL polypropylene radiation sterilized centrifuge tubes and 20 mL of ethyl acetate was then added (Idayat Apanpa-Qasim and Adeyi, 2018). The centrifuge tubes were shaken and mixed on a cyclo mixer at 50 cycles (CM 101) for homogeneity of the samples. The tubes were centrifuged at 5000 rpm at 20 [degrees]C for 20 min. The supernatant was filtered with PTFE micro-fibre syringe filter of 13 mm diameter and 0.22 micron pore size before analysis. The extracts were stored in 2 mL maxipense plastic vials analyzed using GC/MS. The internal standard (benzlyl benzoate) was added to all samples, blanks, and calibrators at known concentration.

Instrument operating conditions is presented in Table 1. Recovery study was carried out and DBP recovery was of 86%.

Statistical analysis. All the analyses were done in duplicate and the results were expressed in minimum and maximum values using MS-Excel. The data were also analyzed by using principal component analysis (PCA), cluster analysis (CA) and correlation coefficient using SPSS (Kumar et al., 2016; Trindade et al., 2015; Li et al., 2009).

Results and Discussion

Only 27 out of the 174 paint samples had DBP identified. The chromatogram and mass spectra of DBP are given in Fig. 1a, b. This was confirmed based on the retention times and the molecular formula.

Concentrations of dibutyl phthalate in the different colours of paint samples by manufacturers based on ISO certification. Seven paint manufacturers with at least one sample each of the same colour were involved in this study. Two of the manufacturers were registered with Nigerian Industrial Standard (NIS) and International Organization for Standardization (ISO) and five unregistered manufacturers without NIS-ISO certification, producing different colours of water-based paints. The concentrations of the dibutyl phthalate in the paint samples with respect to manufacturers are presented in Table 2. Variation in dibutyl phthalate concentrations of paint samples with respect to colours produced by manufacturers are shown in Fig. 3.

The range of levels of dibutyl phthalate in all the paint samples with respect to colour was 721 (cream).47,100 ppb (white). The highest concentrations of dibutyl phthalate in all the 27 paint samples was 47,100 ppb in a white coloured paint by manufacturer A, a registered manufacturer. This was followed by 45,100 ppb in a pink coloured paint and 19,400 ppb in a cream coloured paint by the same manufacturer, while the lowest concentration was 721 ppb in a cream coloured paints produced by manufacturer D, an unregistered manufacturer. The order of dibutyl phthalate with respect to paint colours where present is:

DBP: pink > white > orange > green > blue > cream > yellow > chocolate.

Correlation coefficient. The data obtained in this study was subjected to Pearson correlation coefficient and it was found out that the registration status (registered and unregistered status of the manufacturers) had a positive correlation with manufacturers and dibutyl phthalate versus colour (Table 3). This signifies that the toxicity of dibutyl phthalate should not be underestimated in its usage by manufacturers of paints of different colours.

Principal components analysis (PCA). Two principal components were extracted using the PCA with rotated component matrixes. Corresponding components, variable loadings, and the variances are presented in Table 4.

Only PCs with eigenvalues greater than 1 were considered. PCA of the whole data set yielded 2 data set explaining 86.25 % of the total variance. The first component was responsible for 60.40 % variance and was best represented by the registration status of manufacturers. The second principal component includes all the manufacturers which accounts for 25.85 % of the total variance.

The initial component matrix for dibutyl phthalates indicates that registration status and manufacturers are associated, showing high values in the first principal component (PC1) which explains 52.3% of the total variance and loads heavily on registration status (0.964), manufacturers (0.959). Registration status and manufacturers values are controlled by the producers of paints either registered companies or not. The second principal component (PC2) includes univocally colours and dibutyl phthalates, which accounts for 33.9% of the total variance. Common sources of colours in paints are majorly from pigments, and dibutyl phthalates influences the flexibility of paint produced. The analyzed results are in good accordance with the findings of the correlation coefficient.

Cluster analysis (CA). Cluster analysis (CA) was performed on the data using between-groups linkage method and squared Euclidean distance using the hierarchical clustering with SPSS software (Trindade et al., 2015; Li et al., 2009). Figure 4 shows the CA of dibutyl phthalate in the paint samples as a dendrogram. Two major clusters were obtained. Cluster 1: identified cases 1-3, 8-20, 23-27 and Cluster 2: cases 4 and 5. Cluster analysis revealed a division of the studied parameters into their similar class with respect to their normalized concentration levels.

Conclusion

This study predicts the possible human exposure to dibutyl phthalates in water-based paints, the levels were determined by GC/MS in 27 water-based paint samples. The low levels of DBP in water-based paints coincides with its physico-chemical characteristics (high volatility) that make DBP inappropriate for use in non-plastic products such as paints and probably as plasticizers in PVC found in packing materials. Chemicals such as DBP are used in a wide variety of consumer products (USEPA, 2012) they are suspected endocrine disrupters but their toxicity are poorly understood in paints. Combined exposure may occur through ingestion, inhalation and dermal exposure and their toxic as well as combined effects are poorly understood Larsson et al. (2014). Also, results from multivariate statistical analysis clearly show the use of DBP by all manufacturers for its flexibility and better spreadability in paint production in Nigeria despite its health effects. Hence, a need for stringent regulations to safe-guard public health from occupational exposure to these toxic and prohibited compounds is imperative.

Acknowledgement

Dr Apanpa-Qasim is grateful to The World Academy of Sciences for the Advancement of Science in developing countries and the Council of Scientific and Industrial Research for funding part of this research (FR number: 3240275040). The director of National Environmental Engineering Research Institute, Nehru Marg, Nagpur, India is highly appreciated. Anonymous reviewers are greatly appreciated for their time and contributions in the review of this manuscript.

Conflict of Interest. The authors declare no conflict of interest.

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Ajoke Fehintola Idayat and Apanpa-Qasim (ab*)

(a) Department of Chemistry, University of Ibadan, Ibadan-Nigeria

(b) CSIR-National Environmental Engineering and Research Institute, Nagpur, India

(received July 22, 2018; revised October 19, 2019; accepted November 14, 2019)

(*) Author for correspondence; E-mail: ajoketola@gmail.com
Table 1. Instrument operating conditions
Operating condition     GC-MS                   GC-MS
                                                Monitoring  ions
                                                (m/z) used for
                                                the identification
Analytical column       DB 5 (30mx              149, 150, 41
                         0.25mm * 0. 25[micro]m)

Carrier gas             Helium
Gas flow rate           1.2mL/ min

Injection volume        l[micro]L
Injection temperature   200[degrees]C
Detector temperature    280[degrees]C
Column temperature      l80[degrees]C (0.5 min)
                        -20[degrees]C/min-280[degrees]C
                        7 mins)
Inlet source
temperature             300[degrees]C
Injection mode          split
Solvent delay           4.2 mins
Detector gain mode      relative

Table 2. Concentrations (ppb) of dibutyl phthalate in paint samples with
respect to manufacturers
Colour grouping  Manufacturer codes   NIS-ISO        Primary colours in
                                      registration   the paint samples
NG 01            A                    RG             blue
NG 03            A                    RG             yellow
NG 04            A                    RG             white
NG 05            A                    RG             pink
NG 06            A                    RG             cream
NG 07            A                    RG             green
NG 08            B                    RG             white
NG 09            B                    RG             blue
NG 10            C                    RG             cream
NG 11            D                    WRG            cream
NG 12            E                    WRG            green
NG 14            E                    WRG            orange
NG 15            E                    WRG            cream
NG 17            E                    WRG            green
NG 18            E                    WRG            blue
NG 19            E                    WRG            cream
NG 20            E                    WRG            blue
NG 22            E                    WRG            white
NG 23            F                    WRG            chocolate
NG 24            F                    WRG            blue
NG 25            F                    WRG            green
NG 27            G                    WRG            cream

Colour grouping
                 Sample 1            Sample 2
NG 01            4900                5120
NG 03            4880                -
NG 04            47100               -
NG 05            45100               -
NG 06            19400               -
NG 07            17600               -
NG 08            3400                -
NG 09            8910                -
NG 10            2140                -
NG 11            721                 -
NG 12            5660                -
NG 14            8190                7340
NG 15            4080                -
NG 17            6120                5850
NG 18            8860                -
NG 19            3920                -
NG 20            8050                -
NG 22            15500               15100
NG 23            1470                -
NG 24            3220                -
NG 25            1550                -
NG 27            2610                4190

where RG means registered, WRG means without registration.

Table 3. Correlation coefficient of dibutyl phthalate in the
paint samples
                     Manufacturers   Dibutyl     Colours   Registration
                                     phthalate             status
Manufacturers        1                -0.492**    -0.186        0.923**
Dibutyl phthalate                    1            0.429*        -0.479*
colours                                          1               -0.161
Registration status                                        1

Note:** = significant at 0.01,  * = significant at 0.05.

Table 4: Total variance and component matrixes extracted by PCA
                      Total variance explained
     Initial eigen         Extraction sums        Rotation sums of
     values                of squared loadings    squared loadings
Component             Total    % of       Cumulative   Total    % of
                               Variance   %                     Variance
Registration status    2.416      60.40        60.40    2.416      60.40
manufacturers          1.034      25.85        86.25    1.034      25.85
colours                0.473      11.83        98.09
Dibutyl phthalates     0.077      1.914       100.00

Component             Cumulative   Total   % of variance  cumulative %
                      %
Registration status        60.40    2.094        52.342        52.342
manufacturers              86.25    1.356        33.911        86.254
colours
Dibutyl phthalates
Extraction method: principal component analysis
                   (b) Component matrixes
Component matrix        Rotated component matrix   Compound
                        PC1      PC2               PC1       PC2
Registration status      0.901    0.362             0.964    -0.118
manufacturers            0.910    0.336             0.959    -0.145
colours                 -0.451    0.818          -0.00005     0.934
Dibutyl phthalates      -0.758    0.347            -0.496     0.670
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Author:Idayat, Ajoke Fehintola; Apanpa-Qasim
Publication:Pakistan Journal of Scientific and Industrial Research Series A: Physical Sciences
Geographic Code:9INDI
Date:Sep 1, 2020
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