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Dynamic Stocks and Flows Analysis of Bisphenol A (BPA) in China: 2000-2014 Daqian Jiang, Wei-Qiang Chen, Xianlai Zeng, and Linbin Tang Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b05709 • Publication Date (Web): 13 Feb 2018 Downloaded from http://pubs.acs.org on February 13, 2018
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Dynamic Stocks and Flows Analysis of Bisphenol A (BPA) in China: 2000-2014
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Daqian Jiang,1* Wei-Qiang Chen,2,3,4* Xianlai Zeng,5 Linbin Tang2,3,4
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1. Environmental Engineering Department, Montana Tech, Butte, Montana 59701, United States
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2. Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese
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Academy of Sciences, Xiamen, Fujian 361021, China
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3. Xiamen Key Lab of Urban Metabolism, Xiamen, 361021, China
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4. University of Chinese Academy of Science, Beijing, 100049, China
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5. School of Environment, Tsinghua University, Beijing 100084, China
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Correspondence to:
[email protected];
[email protected] 14
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TOC Art
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Abstract
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Bisphenol A (BPA), a synthetic organic chemical, is creating a new category of ecological and
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human health challenges due to unintended leakage. Effectively managing the use and leakage of
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BPA can benefit from an understanding of the anthropogenic BPA cycles (i.e., the size of BPA
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flows and stocks). In this work, we provide a dynamic analysis of the anthropogenic BPA cycles
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in China for 2000-2014. We find that China’s BPA consumption has increased 10-fold since
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2000, to ~3 million tonnes/year. With the increasing consumption, China’s in-use BPA stock has
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increased 500-fold to 14.0 million tonnes (i.e., 10.2 kg BPA/capita). It is unclear whether a
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saturation point has been reached, but in 2004-2014, China’s in-use BPA stock has been
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increasing by 0.8 kg BPA/capita annually. Electronic products are the biggest contributor,
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responsible for roughly one third of China’s in-use BPA stock. Optical media (DVD/VCD/CDs)
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is the largest contributor to China’s current End-of-Life (EoL) BPA flow, totaling 0.9 million
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tonnes/year. However, the EoL BPA flow due to e-waste will increase quickly, and will soon
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become the largest EoL BPA flow. The changing quantities and sources of EoL BPA flows may
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require a shift in the macroscopic BPA management strategies.
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Introduction
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Bisphenol A (BPA), like many other synthetic organic chemicals, is becoming an important part
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of the material basis of the modern society. Currently, the global BPA consumption has
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surpassed seven million tonnes per year,1 and is expected to continue to increase2, 3 due to the
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wide use of BPA in electronics, automobiles, water bottles, and food packaging.4, 5
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Unlike other bulk materials (e.g., minerals), synthetic organic chemicals present unique
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environmental toxicity and persistence challenges. For example, in the case of BPA, it was found
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that BPA monomers could leach out from BPA-containing products,6, 7 and when it does, it is an
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endocrine disruptor to humans and animals.8-10 Due to the wide use and thereby widely
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distributed sources,11, 12 BPA leakage is widespread. BPA has been detected in food or food
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containers globally,13-16 atmospheric aerosols globally,17 surface water in North America and
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Europe,18 virtually all urine samples in the US population,19 and population in southern China
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with dermal exposure to BPA-containing paper.20 Sometimes BPA is detected in high
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concentrations, e.g., exceedance of Canadian predicted no-effect levels for aquatic life was
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reported in Asia, America, and Europe.11
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To properly manage BPA as a material and the associated toxicity risks, it is helpful to develop a
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macroscopic understanding of the BPA flows and “stock” in society. Stock, or in-use material
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stock, is a concept in industrial ecology, defined as the amount of a material that is in active use
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in society. As products are produced, used, and disposed of (i.e., flows), the amount of in-use
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material stock changes (the exercise of depicting the flows and stock of a material is often
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termed as characterizing anthropogenic cycles). Understanding the changes in flows and stocks
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can provide insights into material sustainability and criticality.21, 22 In some cases (e.g., toxic
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metals), it can also furnish useful insights into managing the risks associated with the unintended
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leakage (flows).23-25
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So far, efforts on systemically characterizing the anthropogenic cycle of synthetic organic
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chemicals are only beginning to emerge.26, 27 Specific to BPA, Pivnenko et al. 2016 delineated
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the BPA cycles in the paper industry, which exemplified how stocks and flows analysis could
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provide useful industry-level insights on the most effective strategies for reducing chemical
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contamination.28 However, at the country level, stocks and flows analysis for BPA remains
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unavailable, with current knowledge limited to BPA flows, such as the tonnage of BPA used in
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producing polycarbonate plastics or epoxy resins annually (which are the primary use of BPA),
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and the tonnage of epoxy resins by different products annually.1
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Herein, we characterize the anthropogenic BPA cycles in China. Understanding the
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anthropogenic BPA cycles can identify hotspots of BPA flows on the national and regional
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scales, and provide a basis for understanding how BPA flows might evolve in the future.
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Understanding the anthropogenic BPA cycles in China also has particular implications in global
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BPA management, as China currently accounts for a quarter of the global BPA consumption, and
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is projected to be the largest BPA consumer, and possibly the largest BPA producer, around
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2020. 29, 30
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Materials and Method
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System Definition
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Figure 1. Framework for the anthropogenic BPA cycle (modified from Chen and Graedel 201221)
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A conceptual framework for the anthropogenic BPA cycle is depicted in Fig 1, which comprises
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five life stages: BPA production, polycarbonate plastics/epoxy resin production, production of
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final products, the use stage, and the EoL management. Each arrow in the diagram represents a
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flow, and each white box represents a stock.
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which are produced directly or indirectly from fossil fuels (particularly petroleum). 31
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BPA production: BPA (Fig S1) is produced via the condensation of acetone and phenol,
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Polycarbonate plastics/epoxy resin production: BPA monomers are often not directly
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used. Globally and in China, over 90% of the BPA monomers are used to synthesize
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polycarbonate plastics (PC) and epoxy resins 1 through the polymerization process (Fig
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S2). Only the BPA contained in PC/epoxy resin flows and stocks are included in this
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study, which is approximately 95% of China’s total BPA consumption. Non-polymerized
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BPA use, such as in thermal paper, is not included.
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Final products: PC and epoxy resins are used in a wide array of products, such as
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automobiles, electronics, and water bottles, among others. Waste flows (e.g., scrap PC)
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are generated in this stage and transferred directly to the EoL management stage.
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Use: The final products that contain BPA are widely used. A portion of the BPA in final
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products will accrue as the in-use stock, and the remaining will be transferred to the EoL
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management. We distinguish between dissipative loss (leakage) and leaching, with
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dissipative loss defined as the material loss in the production process, and leaching
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defined as the unintended release of BPA monomers in the use or EoL phase due to
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chemical reactions (e.g., BPA leaching from PC plastic water bottles7, 16). Only
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dissipative losses are included in this study.
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EoL management: The EoL management includes the landfilling, incineration, and recycling of wastes that contain BPA. Landfilling leads to the accumulation of BPA in
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landfills, and likely, BPA leaching.32 Incineration can destroy BPA completely.33, 34
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Recycling of BPA is also technologically feasible.35, 36
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Data Compilation, Modeling and Analysis
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This section explains the data compilation and modeling methods used in this study. Years 2000-
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2014 are used as the time boundary throughout the analysis. To understand the potential bias
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caused by the truncated time boundary, an initial stock is introduced as part of the uncertainty
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analysis, in which case years 1992-2014 are included.
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BPA production: The BPA flows in the BPA production stage are obtained by harmonizing
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China’s BPA production data from different sources,37, 38 and the customs data,39 which details
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the import and export of BPA in its primary form. The data used are provided in the SI (Table
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S1).
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PC/epoxy resin production: The flows of PC and epoxy resins are obtained by harmonizing the
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customs data,39 and China’s production and consumption data.40-46 The data used are provided in
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the SI (Table S1). The BPA content in PC or epoxy resins is estimated by applying a BPA
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content factor, i.e. kg BPA/kg PC and kg BPA/kg epoxy resin. The BPA content factors are
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primarily based on an industry report,47 which suggests that 0.89 kg BPA/kg PC and 0.7 kg
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BPA/kg epoxy resin are reasonable for PC and epoxy resins, respectively.
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BPA flows to final products: The key final products that require PC or epoxy resin flows are
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identified based on industry report1 and academic publications (Table S2). Optical media
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(CD/VCD/DVDs), construction materials (PC sheets/boards), automobile manufacturing,
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electronic devices/parts, packaging (PC water bottles), and others (medical devices) are the key
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final products that use PC. Paint, electronic parts/devices, construction, and composite materials
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are the key final products that use epoxy resins.
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Statistics on the PC and epoxy resin flows to final products are only available for some years
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(detailed in Table S2). Briefly, PC consumption by final product categories is available for years
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2005, 2007, 2012, and 2014. Epoxy resin consumption by final product categories is available
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for years 2004, 2010, and 2012.
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For years without reported statistics, the PC and epoxy resin flows to final products are estimated
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by multiplying an intensity factor, defined as the PC or epoxy resin content per physical unit of
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the final product (e.g., kg PC per unit of cars), with the production volume of the final product.
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For example, using available statistics, the PC intensity is estimated as 8.0 and 8.6 kg BPA per
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car in 2007 and 2012 respectively. Then the PC intensity for cars in 2008-2011 is estimated as
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(8.0+8.6)/2 = 8.3 kg BPA per car, which is then multiplied by the production volume of
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automobiles in 2008-2011 to obtain the PC flows to auto manufacturing in those years. The
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estimated PC/epoxy resin flows are finally converted to BPA flows using the BPA content
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factors (0.89 and 0.70 kg BPA/kg PC and epoxy resin respectively).
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The parameters used to estimate the PC/epoxy resin intensity factor for each final product are
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detailed in Table 1 in the “Production Volume” column. For example, the PC used in packaging
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is estimated using the PC content per tonne of bottled drinking water produced, while the epoxy
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resins used in electronic products is estimated using the epoxy resin content per tonne of
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electronic products produced (Table 1). The intensity factors for final products with reported
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statistics are provided in Table S1. Imported products are assumed to have identical PC/epoxy
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resin intensity as domestically produced products. The production, import and export data for the
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final products are obtained from China’s Statistical Yearbook,39 and trade data.39, 48
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Table 1. The parameters used to estimate the PC/epoxy resin flows to different final products Type of Parameter
Sector GDP (RMB)
Production Volume (physical units)
PC
Optical media
units of CD/VCD/DVDs
printing and recording media production
Construction materials (PC boards)
tonnage of PC boards
construction
Automobiles
units of passenger cars
auto manufacturing
tonnage of bottled drinking water total weight of electric appliances/devices
wholesale and retail of beverages manf. electrical machinery/equipment; manf. wholesale and retail of electric electronic/communication equipment household appliances wholesale of construction total area under construction materials
Packaging Electronic devices/parts
Epoxy Resins
Wholesale and/or Retail (RMB) retail of audio/video/epublications wholesale of construction materials wholesale and retail of autos
food, beverage, tabacco production
Paint
tonnage of paint
Electronic devices/parts
total weight of electric appliances/devices
manf. electrical machinery/equipment; manf. wholesale and retail of electric electronic/communication equipment household appliances
Construction
finished area under construction
construction
wholesale of construction materials
Auto & composite materials
units of passenger cars
auto manufacturing
wholesale and retail of autos manf. stands for "manufacturing of"
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In-use BPA stock: The in-use BPA stock is the accumulation of BPA in the final products that
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are in active use. For each final product, the BPA accumulated in in-use stock is calculated as
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follows:
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= + ∆
(Equation 1)
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, ∆ = ∑( , − )
(Equation 2)
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, =
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, =
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where is the in-use stock at the end of year t+1; is the in-use stock at the end of year t;
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∆ is the change of in-use stock in year t+1; , is the input to the BPA stock through
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product i in year t+1, which is the sum of domestic production ( , ) and import
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!"#$ , ( +1 ); , is the output from BPA stock through product i in year t+1, which is the
,
,
,
+
(Equation 3)
+ ,
(Equation 4)
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%#&, , sum of export ( , ) and EoL flow ( +1 ). , , and ,
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are estimated using the method explained in the previous section. The estimation of , is
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described in the next section.
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EoL BPA flows: EoL BPA flows are estimated using lifetime models. For optical media,
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construction media, automobiles, packaging, and paint, the generation of EoL BPA flows
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( , ) is estimated based on the normal lifetime model (assuming that the lifespan of a
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product in in-use stock follows the normal distribution):
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, = ∑(+,--- ' (, − (
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(, = .
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where , is the EoL BPA flow (contained in product i) in year t+1; (, is the
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probability for product i that was produced in year j to reach EoL in year t+1;
