| Common phthalates and their uses in industry [7] | ||||||||||||||||||||||||||||
|
Introduction
Plasticizers are substances that are added to a material to increase its plasticity, namely, its flexibility and durability. Phthalates are the most commonly used type of plasticizers and are popular due to their relatively low cost, low volatility, and ability to create very elastic materials. Today, phthalates are the most ubiquitous man-made chemicals found in the environment [1]. However, the global proliferation of the phthalate, polyvinyl chloride (PVC) and the numerous products containing PVC, are known to have caused significant health issues.
The name “phthalate” stems from phthalic acid, which refers to three isomers—ortho-isomer or phthalic acid, tere-phthalic acid, and meta-isomer iso-phthalic acid. Phthalic acid esters are commonly used in PVC production, whereas tere-phthalic acid esters are used in the production of bottles for carbonated drinks. Iso-phthalic acid esters are the least common but are nevertheless used to create resins for numerous products, including foods [2].
The most commonly used phthalates are ortho-phthalates and tere-phthalates. Ortho-phthalates, which will subsequently be referred to as just “phthalates”, are produced by reacting phthalic anhydride with a range of alcohols such as methanol, ethanol, and tridecyl alcohol [3]. The ortho-phthalates are divided into two main categories: high-molecular-weight (HMW) and low-molecular-weight (LMW) ortho-phthalates [4]. HMW phthalates have 7–13 carbon atoms in the backbone of their structure, whereas LMW phthalates have 3–6 backbone carbons. When these molecules are incorporated into polymers, they reduce interactions between adjacent polymer chains. This serves to increase flexibility in the plastic by significantly lowering the glass-transition temperature [5]. The effect that phthalates have on the flexibility and toughness of polymers makes them ideal, in a mechanical sense, for use in many different applications, including wires and cables, flooring, adhesive films, medical equipment, cosmetics, coated fabrics, roofing membranes, synthetic leathers, and automobile plastics [3].
The basic structure of a phthalate is a benzene dicarboxylic acid with two side chains, which can be alkyl, benzyl, phenyl, cycloalkyl, or alkoxy groups. The following figure shows the chemical structure of selected phthalates. The defining characteristics of each phthalate and its decomposition pattern are determined by the length of the dialkyl side chain. If a phthalate is more branched then it has more isomers available and is also more hydrophobic. In other words, it can more easily be integrated into ground water.
HMW ortho-phthalates represent 70% of the plasticizers market, whereas LMW ortho-phthalates comprise about 5% [3]. HMW ortho-phthalates are not yet determined to be endocrine disrupting or carcinogenic, mutagenic, or toxic to reproduction, however, based on studies of rats that show detrimental liver effects, there is reason to be concerned, and there are restrictions on the use of DINP and DIDP for childcare products [3].
LMW ortho-phthalates are classified as dangerous substances by the European Union’s REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) regulation. In particular, LMW ortho-phthalates have been found to be damaging to reproductive health [4].
In the electronics industry, plasticized PVC forms the coatings on wires and various plastic parts in electronic devices. Some of the most common phthalates found in PVC applications include DEHP, DBP, DEP, and DiNP. DEHP was historically the most commonly used phthalate for plasticizing PVC, but in 2015 it was banned in most product applications in Europe due to concerns over its endocrine-disrupting potential. It is likely that all the phthalates will eventually be found to be harmful and banned, since they all have the same foundational composition. The following figure shows the synthetic steps of DEHP [47].
Due to evolving restrictions on phthalates and an increasingly wary public, many electronics companies are seeking replacements for the chemicals traditionally used in their products. Apple has started the Full Material Disclosure program, wherein a company discloses the chemical composition of components used in the manufacturing of their electronics [8]. Before 2013, phthalates were used in Apple’s power cords and headphone cables but since then they have been replaced with more environmentally friendly alternatives such as thermoplastic elastomers. Apple’s current products are claimed to be free of PVC and phthalates with the exception of those manufactured in South Korea and India where Apple is seeking government approval for replacement materials [8]. Furthermore, while Apple claims to have replaced all PVC and phthalates, they do not specify the exact materials used in the production of their devices.
A 2014 update of the Greenpeace 2007 hazardous materials report [9] presented the steps taken by electronics companies over time to reduce phthalates among other hazardous materials. According to the report, as of 2014, 50% of the mobile device market was completely free of PVC. Compared to mobile phones, less progress was made towards removing hazardous chemicals of concern from laptop computers. In particular, while many companies have reduced the amount of PVC in their computers, other phthalates are being used and charging cables are often still made from PVC.
E-Waste
Phthalates in the Electronic Products
Our modern way of life relies heavily on electronic devices. From home, to work, to entertainment, electronics are everywhere and are perpetually being built, replaced, and disposed of. This disposal process is where many of the hazardous materials used in electronics pose the greatest threat. During the disposal process, electronics may go through acid baths, incineration, and landfills [24]. Disposal becomes especially hazardous when done by unskilled workers, often in developing countries, as is the case with much of the world’s e-waste.
Phthalates are commonly found in landfills since, as expected, e-waste is often disposed in these locations. But more interesting is that phthalates are ubiquitous in freshwater and also tend to absorb in sediment. In Taiwanese rivers, there was 0.1 to 18.5 μg/L of DEHP and 0.5 to 23.9 μg/g in sediment. It was also shown that phthalate-degrading organisms are not common in these environments.
Phthalate exposure is significant in electronic waste (e-waste). A 2007 report by Greenpeace [25] measured the amounts of various toxic chemicals found in laptop computers manufactured by companies such as Apple, Dell, Toshiba, Acer, Sony, and HP. The study included a test for nine different phthalates including DBP, BBP, DEHP, DOP, DMP, DEP, DiBP, DiNP, and DiDP. The highest concentrations were found in Acer and HP laptops with 18–29% by weight. Toshiba laptops had concentrations of 13% and Dell and Sony laptops had concentrations of 3.4–9.5%. Apple’s laptops were shown to have total concentration of phthalates ranging from 0.2–0.3% by weight. The phthalate concentrations were dominated by DiNP and DiDP, with a smaller contribution from DEHP. Upon disposal, phthalate plasticizers, which are incorporated into electronic components, can leach out into the ground water [7].
Polypropylene (PP) is a low-cost polymer that is commonly used to produce plastics that have good mechanical properties for manufacturing, including high stiffness and heat resistance. However, PP is reported by the University of Cincinnati [26] [27] to have relatively high concentrations of phthalates such as DnOP, DIBP, and DEHP. PP is found in plastic and rubber materials, adhesives, and sealants that can be components of electronic products.
Concerns with the Disposition of Electronic wastes (E-wastes) in the World
While electronics companies have begun scaling back the use of phthalates under public pressure and increasing regulation, production changes are only part of the solution. The pathways that electronics take when they have reached the end of their life-cycle can have as much effect as the materials used in their construction. Even as companies reduce the levels of toxic materials in their products, large amounts of e-waste are improperly recycled or simply disposed of in poorer and less regulated parts of the world [24].
Developing countries in Africa and parts of Asia lack both the regulations and the systems necessary to cleanly and sustainably recycle e-waste [28]. In many impoverished areas, unskilled workers comb through e-waste and break down old electronics to extract useful and valuable materials. The working conditions in these types of operations often allow direct exposure of workers to chemicals through touch and inhalation during the waste disposal processes of dismantling, shredding, acid baths, and incineration. In addition to heavy metals and other toxins found in e-waste, phthalates such as DEHP, DINP, DBP, BBP, and DIBP can be found, mainly in PVC coatings for wires and cables.
In a study conducted by the Bulletin of Environmental Contamination and Toxicology [29], nine e-waste soils were collected from Fengjiang, Nanshan, and Meishu sites in Taizhou City, China. Because e-waste is a significant problem in Asia, there is more urgency to understand the potentially hazardous effects of phthalates through the environment. Taizhou is located in south China and is one of the largest e-waste disposal centers in the country. Of all the samples recorded, the total concentration of phthalates ranged from 12.566 to 46.669 mg/kg. DEHP had the highest concentration relative to the other commercial phthalates tested (DMP, DEP, DBP, DEHP, and DNOP), constituting 50% of the total phthalate content. Soil tests from e-waste contaminated areas also show that phthalates are likely to seep into the environment, and illustrate the importance of proper e-waste handling.
Increased demand for technology in developing areas obviously leads to larger sales of electronics, but waste also enters through illegal imports as well as donations from other countries [28]. While some shipments of donated electronics to developing nations are legitimate, some of the second-hand electronics brought into countries are already broken or past their usable lifetime, and are only marked as donations as a way to illegally export them from their country of origin [28]. In many developing countries, the demand for technology is booming, and the massive influx of electronics coupled with countries’ inability to fund proper recycling plants has created huge exposure risks. According to a report [30], in 2007, India generated 380,000 tonnes of waste electronics, which included an estimated 50,000 tonnes of donated second-hand electronics from developed countries. While the flow of e-waste between countries is complex, and regulations vary throughout different parts of the world, there is a tendency for used electronics to end up in developing countries.
The governments of developing countries cannot be expected to bear the burden of this problem alone. Manufacturers and suppliers must take responsibility for the final disposition of their products. Saoji [30] asserts, “Recycling of e-waste is beyond the means of a consumer or local government, given its toxic nature. The solution lies with the brand owners or manufacturers of electronic products, which need to bear responsibility for financing the treatment of the own-branded e-waste.” That is, electronics companies not only have a responsibility to manufacture their products with the safest materials possible, but also must work to enable the proper disposal of their products, which entails providing outlets for recycling electronics everywhere that they are available, and not just in developed countries where it is required by law.
Puckett et al. [31] noted that the Basel Action Network (BAN), an environmental watch group, placed tracking devices in 200 old electronic devices such as LCD monitors, CRT monitors, and printers. The electronics were then distributed to several different public e-waste recycling facilities across the U.S. With the assistance of MIT’s Senseable City Lab, a research group that studies the effect of technology on urban growth, the devices’ locations were tracked, and a map was made of their routes. The results showed that 65 of the devices were exported, with 62 (31% of all the devices) exported illegally based on the e-waste laws of the countries where they ended up. The majority of the exported devices were taken to Hong Kong (and likely then sent to mainland China), with the rest going directly to mainland China and Taiwan. Another part of the 200 devices, a subgroup of 28, were dropped off at Goodwill stores that were participating in the Dell Reconnect public e-waste takeback program [31]. Six of these 28 devices (21%) were among those eventually exported to Asian countries. While the authors of the study recognize that the sample size of the experiment is too small to extrapolate to determine patterns in e-waste flow, it is no less troubling that a significant portion of the devices made their way to Asia. Dell’s e-waste recycling policy states that they prevent the export of any e-waste, and were in fact the first company to do so. Thus, the BAN study [31] shows that even in the most developed and trusted recycling programs, there can be implementation challenges.
Degradability of Phthalates into the Environment
To prevent the exposure of phthalates to the environment, safe disposal practices must be adopted. One pathway for eliminating phthalate exposure is to create biodegradable phthalates. However, phthalates with long ester chains, such as DCHP, DHP, DOP, and DEHP, do not biodegrade easily [2]. The biodegradability of longer ester chained phthalates can be due to the spacing of the atoms in the phthalate side ester chain, which inhibits the ester’s ability to bind to the hydrolytic enzymes, thereby impeding the hydrolysis process. Furthermore, biodegradation of each phthalate is different, and while most phthalate-degrading organisms are aerobes (microorganisms that need oxygen in order to grow) some are facultative anaerobes (microorganisms that can grow with or without oxygen).
Microbial absorption of phthalates cannot be performed by a single type of microorganism but instead requires mixed cultures of microorganisms to completely assimilate phthalates into the environment. Aerobic phthalate degradation is shown to be faster than anaerobic degradation through additional studies. Microorganisms have been used to degrade phthalates in multiple environments. Examples of phthalate-degrading organisms are bacteroids/chlorobi, proteobacteria, actinobacteria (or high G + C), and firmicutes (or low G + C) [1].
The discharge from sewage works is a major source of phthalates in the environment. DEP and DEHP were found to be the most common phthalates with ranges of 1–74 and 28–122 μg/L, respectively. Generally, phthalates are not degraded in the wastewater treatment process due to their high hydrophobicity and low solubility. These characteristics cause phthalates to be transferred to settled sludge. Although phthalates are commonly found in wastewater treatment, studies have shown that phthalates can be removed from water by sequencing batch reactors, up-flow anaerobic sludge blanket (UASB) reactors, and packed-bed reactors [2].
Phthalate concentrations in sediment can also be a potential problem due to migration into aquatic environments. According to an article [32] highlighting a study by M. D. Williams and colleagues, the sediment partition coefficients of phthalate esters were investigated. The study found that by using the Freudlich equation to describe the sediment partition coefficients, the partition coefficients decreased as the particle concentration increased. According to the authors, this could have been caused by complexation or particle-induced adsorption. The partition coefficients were shown to be 1 to 3 times the order of magnitude lower than of the octanol-water coefficients. It is shown that sediment pore-water concentration estimates are overstated if the partition coefficients do not take into consideration the effects of solids.
Phthalates can be transported and leached out of a variety of places, some of which are through air and water. In a study conducted by Xie et al. [33], a German research ship called the FS Polarstern gathered air samples from “the Norwegian Sea to the Arctic using a high-volume air sampler equipped with a PUF/XAD-2 column for gas-phase com- pounds and a glass fiber filter”. Furthermore, water samples (500-1000 L) were collected from a stainless steel seawater inlet, which was located at the keel of the ship 11 m in depth. The water samples showed phthalate concentrations are higher in coastal areas than in central areas with water. According to the authors, this could be due to the release of phthalates from melting snow during the polar summer. The results also showed that DnBP and DEHP in the central Arctic had concentrations of 1 to 3 orders of magnitude lower than of the concentrations found in the Gulf of Mexico and German Bight. The results suggested that phthalates can be discharged through rivers and partially transported to open seas through currents. The air samples showed that in the remote Arctic concentrations of DnBP and DEHP were lower by a factor of 2 to 3 than those found in the North Atlantic and North Pacific. Also, urban and rural air had phthalate concentrations 1 to 2 orders of magnitude higher than in northern oceans.
Phthalate degradation requires specific inocula because each phthalate’s biodegradation process is different. The processes found in water treatment plants are not effective for biodegrading DEHP, and biodegradation only accounts for 20% removal while the remaining percentage is from other processes. Phthalates are found at high concentrations in sludge due to urban runoff, drainage, and domestic and industrial discharges. In composting, high concentrations of DEHP (60 mg/L or more) have been shown to decrease the rate of biodegradation of other phthalates from 48% to 6% due to partial metabolism and the production of 2-ethyl-hexanol, which is toxic to the microorganism that degrades some phthalates. With appropriate conditions (e.g., proper ventilation, moisture, and sunlight), the half-lives of DEHP in lagoon sludge and activated sludge are about 45.4 and 28.9 days, respectively [2].
The degradability of phthalates is also essential to understanding how phthalates can be prevented in various environments. According to a study conducted by Ejlertsson, et al. [34] the degradability and water solubility of phthalates BEHP, DEHP, DBP, DHP, DOP, and DDP, was investigated using a methanogenic butylbenzyl phthalate (BBP) degrading enrichment culture. In addition, resistant PAEs (phthalic acid esters) were investigated to see if the degradability could be stimulated with the addition of a PAE known to be degradable. The results indicated DBP, BBP, BEHP, and DHP, which had higher, water solubilities (ws) (ranging from 11.2 mg/L to 50 μg/L) degraded whereas, DEHP, DOP, and DDP which had lower ws values of 3 μg/L and 0.5 μg/L, did not. These results suggest water solubility is a major factor limiting the degradation of PAEs. In addition, it was found that phthalates with high ws values such as DMP (4 g/L), DEP (1 g/L), DBP, and BBP, BEHP, and DHP were degraded to methane and carbon dioxide, but DEHP and phthalates with hydrophobic properties did not readily degrade. It was also noted in the article, organisms that degrade less resistant phthalates could stimulate anaerobic degradation of persistent PAEs.
Health
There have been growing concerns over the effects of phthalates on human health, especially on the reproductive system. Phthalates pose the biggest threat to infants and children and are passed from a mother to a fetus. Multiple rodent studies have shown that phthalates can be transferred from mother to offspring in utero as well as through breast milk [6]. In humans, breast milk carries the hydrophobic phthalates di-n-butyl phthalate (DBP), and possibly longer-branched DEHP and DiNP as well as their metabolites. Phthalates are split into these monoester metabolites after hydrolysis, which is the first step in the metabolism of phthalates.
Metabolism of phthalates occurs in two steps—hydrolysis and conjugation. During the first step, hydrolysis, diester phthalates are broken down to monoester metabolites by lipase as well as esterase enzymes in the small intestine and parenchyma. Small-branched phthalates are excreted as monoester phthalates through the urine, whereas longer-branched phthalates undergo more biotransformation until they are also excreted through the urine. The second step, conjugation, is catalyzed by the enzyme uridine 59-diphos-phoglucuronyl transferase. Conjugation produces the hydrophilic glucuronide conjugate. This process usually occurs with longer-branched phthalates, and the resulting conjugates are excreted through the urine [6]. Each phthalate has several metabolites that are hydrolyzed and eventually passed through the urine. The following figure illustrates the metabolic pathways of phthalates [6].
In addition to the metabolism of phthalates, migration processes are noteworthy to phthalate exposure. Migration processes have been shown to be significant in infant food. In a study conducted by Gärtner et al. [10], 20 infant food samples packaged in paperboard containers were examined for phthalate concentrations. Migration was tested for two conditions, direct transfer and gas transfer at 40 oC. The results showed DiBP was present in the infant food at a concentration of 20.3 ng/g. In addition, the food samples with the highest concentrations of phthalates were packed with secondary packaging made of paper. In the direct transfer condition, it was shown that paper is incapable of preventing migration of phthalates to food samples. Also, migration of phthalates is dependent on the diffusion coefficients as well as the partition coefficients of the paper and food sample. It was shown that the migration of phthalates was dependent on the porosity of the paper packaging and size of the phthalate molecule. In the gas transfer condition, DiBP and DnBP were shown to migrate in a linear fashion over a period of 60 days. Furthermore, since phthalates are not covalently bound to the plastic matrix, they can leach out to the environment to increase the likelihood of exposure to humans.
Reproductive Defects of the Phthalates
The presence of endocrine-disrupting chemicals during the developmental stages of life can have lasting health effects. Frederiken and Skakkebaek’s studies [6] conducted by Turku University Central Hospital, Finland [11], University Hospital of Toulouse, France [12], the Department of Growth and Reproduction, Rigshospitalet, Denmark [13], and the University of Turku, Finland [14], all noted reproductive defects that may be caused by endocrine disruptors, including hypospadias, cryptorchidism, and testicular cancer. Skakkebæk et al. [15] noted the prevalence of infertility and genital birth defects in several Western countries, as well as decreasing fertility rates associated with the prevalence of endocrine disruptors. Frederiken and Skakkebæk [6] also suggested that there is strong evidence of a link between reductions in human fertility rates and the health effects observed in phthalate experiments with rodents.
In adult men, it was found that higher ratios of MEHP/MEHHP or MEHP/MEOHP (ratio of metabolite to phthalate) resulted in greater DNA sperm damage [6]. The ratio of phthalate metabolites was more significant than the individual contribution of each metabolite in determining the detrimental effects of phthalates on endocrine function. Metabolite concentrations were measured in breast milk through the collection of samples from a group of breast-feeding mothers. The phthalate monoesters MMP, MEP, MBP, MBzP, MEHP, and MiNP were observed in the breast milk samples. The levels of reproductive hormones present in the infants were shown to correlate with the levels of phthalate metabolites in the breast milk [6]. Urine excretion of phthalates showed that children had four times the concentration of phthalates in their bodies than adults. More evidence is still needed on the effects of phthalates on different age groups to understand why children are more at risk than adults.
Dewalque et al. [16] evaluated phthalate concentrations of five different phthalates in Belgium—DEP, DnBP, DiBP, BBzP, and DEHP in urinary pathway analysis. Bisphenol A (BPA) and other pollutants demonstrated anti-androgenic effects (adverse effects on endocrine function), suggesting that there should be a better method of measuring endocrine disruption that could distinguish between phthalates and pollutants. DEHP was found to be the primary contributor of phthalate exposure through food consumption. The other methods of exposure were shown to have lesser contributions as pathways for endocrine disruptors. It was also shown that other exposure pathways besides dietary were more pertinent for the exposure of phthalates in young adults. 6.2% of adults showed a significant level of phthalate exposure, which is considered to be high, and 25% of children showed a significant level of phthalate exposure. This difference demonstrates that children are more susceptible to phthalate exposure than adults. These results of high-level exposure were shown for DEHP, DiBP, and DnBP.
Results of transgenerational studies show that the reproductive systems of developing non-human animals are prone to the adverse effects of certain phthalates [17]. Andrade [17] investigated the harmful effects that phthalates have on the male rat reproductive system by interfering with follicle-stimulating hormone action on Sertoli cells. It was also shown that phthalates interfere with the development of androgen-dependent organs, which contribute to conditions such as cryptorchidism, hypospadias, and reduced sperm count.
Non-dietary Effects of the Phthalates
The School of Public Health at the University of Texas, among other research institutions, conducted a study of phthalate concentrations and consumption of 9 phthalates in 72 commonly purchased foods in Albany, New York [18]. The study used gas chromatography and mass spectroscopy to investigate the presence of DEHP, DMP, DEP, BBzP, DBP, DiBP, DnHP, DCHP, and DnOP in those foods. The results showed that DEHP was present in 74% of the tested foods, with the prevalence of the other phthalates ranging from 30-60%. The phthalate with the highest concentration by far was DEHP, with a peak concentration of 300 ng/g (present in pork samples). The study concluded that while the levels of phthalates in food products were far below the EPA’s reference doses, the contributions of non-dietary phthalate absorption must also be considered. Additionally, even with small levels of phthalates present in food, bioaccumulation presents a problem and must be studied further.
A study showing the detrimental effects of phthalates on workers was conducted by the Department of Environmental Science and Engineering at Fudan University, China, and the Nanjing General Hospital, China [19]. In this study, 456 workers from PVC factories were identified, 352 workers from the production department comprised the exposed group, and 104 office workers comprised the control group. The exposed workers ranged from 20 to 45 years old. Blood sampling was performed before and after 3 years of working in the same place. Results showed that increased exposure to DEHP caused illnesses that ranged from minor respiratory problems to neurotoxic diseases. Respiratory and minor problems included headache followed by dizziness, fatigue, nausea, muscle weakness, vomiting, skin rash, shortness of breath, and asthma. Serum PChe (the chemical used for testing health effects) was routinely used to measure the weight of the liver over the course of the 3 years of exposure to DEHP. Decreased liver weight was shown as a potential effect of DEHP exposure along with decreases in PChE levels, increased oxidative stress, and abnormal liver function. Researchers also noted DEHP residue in the plasma of workers [19].
In a study conducted by Rudel et al. [20], the concentrations of phthalates and other compounds were determined in air and dust. The study involved the investigation of indoor air and house dust samples from 120 homes on Cape Cod, MA. The results showed high concentrations in both air and dust. In indoor air it was shown that DEP and DBP had the highest concentration. In dust, DEHP and BBP were the highest in concentration. The results suggest that inhalation is a significant route of phthalate exposure and that there should be extensive research conducted in the future on the effects of indoor exposure of phthalates on health, including in manufacturing facilities.
Why phthalates cause endocrine disruption?
Ritter [21] investigated how phthalate size and shape affected hormone receptor proteins and enzymes involved in the synthesis or activation of hormones. It was found that some hormones such as 27- hydroxycholesterol bind activate estrogen receptors despite having long alkyl side chains. Long side chains are also evident in phthalates, thereby suggesting a possible correlation between the hormone regulation and phthalates through the ability to bind through side chains. Another study [22] by the University of Lille in France found that phthalates interact with PPARs (peroxisome proliferator-activated receptors) via contacts with the aromatic ring and alkyl side chains. DEHP was found to weakly bind to PPARs whereas diisononyl cyclohexane-1,2-dicarboxylate (DINCH), tris(2-ethylhexyl) trimellitate (TOTM), and acetyl tributyl citrate (ATBC) were incapable of binding to PPARs. In an EPA study by Gray et al. [23], pregnant rats were tested to see what effect phthalates had on their testosterone and sexual development. It was revealed that problematic compounds had common alkyl chain length, molecular weight, and ability of digestive enzymes to cleave an alkyl chain to form a monoester.
Alternatives
Over the past decade, environmental groups, consumers, and government legislation have pushed companies to search for phthalate alternatives. Regardless of the alternatives, in order to successfully phase out phthalate plasticized PVC, substitutes must be easy to process with conventional equipment, stand up to the required mechanical properties, and be manufactured at reasonable prices. When selecting an alternative, manufacturers must often make trade-offs by sacrificing some desired material properties for others that are deemed priorities. For example, it is possible to use less environmentally detrimental polymers such as EVA as alternatives to PVC, but they do not provide mechanical properties as desirable as PVC’s [42].
Requirements for Alternatives
The need for alternatives for phthalates has led manufacturers to create alternatives that share many properties of the phthalate plasticizers without creating endocrine disruption. According to one of the studies conducted by Gray et al. [23], di(2-ethylhexyl) terephthalate (DEHT, see the following left figure) is considered to be a phthalate alternative that has no disruption in sexual development in male mice relative to DEHP. This can be due to the structure of DEHT. DEHT is a terephthalate, which has ester groups on opposite sides of the phenyl ring as opposed to the groups being adjacent to each other. This hinders the ability of DEHT to bind hormone receptors and/or metabolize to a monoester [23]. According to Daniel Schmidt of the Department of Plastics Engineering at the University of Massachusetts, Lowell, DINCH (see the following right figure) is another phthalate alternative that can be used as an alternative to DINP and that is commonly used in wires due to its high molecular weight, which makes it less likely to migrate out of plastic. His recommendation for manufacturing plasticizer alternatives was to avoid aromatic rings, which can lead to endocrine disruption.
The trend to find phthalate alternatives has led environmental groups to create guides that assist electronics companies in eliminating hazardous substances from their products. The most commonly sought-after alternatives are thermoplastic elastomers and bio-based plasticizers. In 2010, a new family of phthalate-free plasticizers was used for wire insulation and jacketing. These plasticizers have shown superior performance and are also made from almost completely renewable feedstocks [43]. However, they remain to be widely accepted.
Thermoplastics, unlike phthalates, can be used in injection molding for small geometries (less than 2 mm) and complex shapes. This enables manufacturers to design smaller and lighter-weight hardware. For example, polycarbonate/acrylonitrile butadiene styrene (PC/ABS) blends have been used in electronic enclosures due to their high modulus, ductility, heat resistance, and impact strength, and are relatively inexpensive. Compositions of thermoplastic elastomers (TPEs) include thermoplastic olefins (TPE-O), copolyamides (COPA), copolyesters (COPE), styrenic compounds (TPE-S), thermoplastic polyurethanes (TPE-U), and vulcanizates (TPE-V) [44]. TPE-V is more flexible and more resistant to extreme temperatures, unlike PVC, which shrinks (Sarlink TPE-V).
TPEs can be extruded, injection-molded, and thermoformed. These are the popular processing techniques that make TPEs easy to use for manufacturing. Medical products made in theblow/fill/seal process can use TPEs for high-temperature manufacturing, whereas for other plastics such as polyethylene there is a temperature limit of around 121 °C. High-performance TPEs can be over-molded (over-molding eliminates failure of parts by creating chemical bonds between the plastic substrate and the TPE) onto rigid parts. This helps increase the longevity of parts and cost efficiency in manufacturing. Some TPEs can stretch up to 10 times their original length without permanent deformation, and while most TPEs can withstand 400 to 1,000 psi in tension, the wide range of TPE formulations allows some to reach tensile strengths of 5,000 psi [45][46].
Health and Environmental Concerns with Alternatives
According to a report from the University of Massachusetts [7], examples of chemical phthalate alternatives include citrates, sebacates, adipates, and phosphates. Like phthalates, chemical alternatives are typically not chemically bound to the plastic they are added to. Therefore, the alternatives can also migrate out and adversely affect the environment and human health. The major health concerns include respiratory illnesses such as asthma as well as skin and eye irritation. However, environmental effects of chemical alternatives can also include adverse effects on aquatic life such as fish, algae, and crustaceans. In addition, several chemical alternatives do not easily biodegrade and accumulate in the environment.
One class of alternative plasticizers to phthalates is bio-based plasticizers. Bio-based alternatives can be made from plant materials such as corn, soy, rice, wheat, and linseed, which makes them much less threatening to animal life. Seven out of the eleven given examples in a report [7] on bio-based alternatives are listed as biodegradable and compostable. Health concerns for these alternatives include skin and eye irritation, respiratory illnesses, and adverse effects on the nervous system. While bio-based alternatives are made from environmentally friendly materials, they are also made from GMOs (genetically modified organisms). Since it is unclear what effects GMOs may have on the environment, it is conceivable that bio-based plasticizers may have unintended effects on the natural environment.
In a study conducted by Benaniba and Massardier-Nageotte [5], epoxidized sunflower oil (ESO) was used as a bio-based co-plasticizer in PVC. The study discussed the effects of ESO when it is used with DEHP on the plasticized material. With 25 wt% of plasticizer, the hardness of the material consisting of DEHP and ESO is lower than the material that uses only DEHP (testing was conducted using the Shore A and D hardness test). In addition, the tensile strength of the plasticized material consisting of both ESO and DEHP was lower than the DEHP plasticized material (tensile strength testing was conducted through a traction test at room temperature at a speed of 20 mm min-1 using a 0.5 KN load cell). Migration was another characteristic that was measured through weight reduction at high temperatures. It was found that compositions consisting of high levels of DEHP and low levels of ESO had higher weight losses. Plasticizer migration was found to be proportional to the concentration, the temperature, the composition, and the nature of the model leachate. Moderate improvements in the measured properties of the plasticized PVC were shown at low levels until ESO was 25% incorporated. The ESO co-plasticizer was shown to be more environmentally friendly than phthalate plasticizers, and with the ideal composition, it can produce improved mechanical properties.
Legislation
Different countries and regions have their own ways of regulating the use of dangerous chemicals in industry. While phthalate use is not controlled in many developing countries, certain entities such as the European Union and the U.S. government have developed legislation, although still limited, to address health concerns over phthalates.
European Commission
The European Delegated Directive (EU) 2015/863 [35,48], published in March 2015, added four new phthalates to the restrictions on plasticizers. DEHP, BBP, DBP, DIBP are limited to less than 0.1% concentration in all cosmetic products, children’s toys, and electronics products. These restrictions are in part due to the reported endocrine-disrupting capabilities found through research and will be enacted starting on July 22, 2019. Medical and monitoring equipment are given two additional years to comply (by July 22, 2021). Applications regarding the usage of these phthalates must be submitted and reviewed. Until the day of enactment, electronics companies can still use DEHP, BBP, DBP, and DIBP.
In 2007, DEHP, DBP, and DINP were restricted and limited in consumption. Entry 51 of Annex XVII to Regulation (EC) No. 1907/2006 specified the restriction of DEHP, BBP, and DBP in toys. For the Directive 2011/65/EU, there is still a need for an adaptation of the regulation due to the fact that companies that may apply for usage of these phthalates in manufacturing may have the ability to cover exemptions of the regulation during the entire life cycle of the electronic component. The phthalates currently included on REACH’s Candidate List include dihexyl phthalate, dipentyl phthalate (DPP), diisopentyl phthalate, N-pentyl-isopentyl phthalate, bis(2-methoxyethyl)phthalate, diisobutyl phthalate, benzylbutyl phthalate (BBP), DEHP, and DBP.
The European United [36] has banned DEHP, DBP, and BBP from all toys and child care products. Also, DINP, DIDP, and DNOP would also be essentially banned with the new restrictions. In 1999, a risk assessment of DINP, DEHP, DBP, and BBP showed that DINP had essentially no reproductive risks associated with it. Even though there is evidence to support the low risk of DINP, the EU has unanimously decided to ban the phthalate from toys. According to Tim Edgar, deputy director of ECPI, "We are faced with a purely political decision, ignoring the scientific risk assessment."[36]
In 2007, DEHP, DBP, and DINP were restricted and limited in consumption. Entry 51 of Annex XVII to Regulation (EC) No. 1907/2006 specified the restriction of DEHP, BBP, and DBP in toys. For the Directive 2011/65/EU, there is still a need for an adaptation of the regulation due to the fact that companies that may apply for usage of these phthalates in manufacturing may have the ability to cover exemptions of the regulation during the entire life cycle of the electronic component. The phthalates currently included on REACH’s Candidate List include dihexyl phthalate, dipentyl phthalate (DPP), diisopentyl phthalate, N-pentyl-isopentyl phthalate, bis(2-methoxyethyl)phthalate, diisobutyl phthalate, benzylbutyl phthalate (BBP), DEHP, and DBP.
The European United [36] has banned DEHP, DBP, and BBP from all toys and child care products. Also, DINP, DIDP, and DNOP would also be essentially banned with the new restrictions. In 1999, a risk assessment of DINP, DEHP, DBP, and BBP showed that DINP had essentially no reproductive risks associated with it. Even though there is evidence to support the low risk of DINP, the EU has unanimously decided to ban the phthalate from toys. According to Tim Edgar, deputy director of ECPI, "We are faced with a purely political decision, ignoring the scientific risk assessment."[36]
Consumer Product Safety Commission
The U.S. Consumer Product Safety Commission (CPSC) has published toxicity reports highlighting the adverse effects associated with BBP, DBP, DEHP, DIDP, DINP, and DnOP [37]. As a result, these phthalates were banned in the Consumer Product Safety Improvement Act (CPSIA) of 2008 for children’s toys and products. The Commission relied upon the Chronic Hazard Advisory Panel (CHAP) and their own health sciences staff to investigate the potential health effects on humans, focusing particularly on infants, children, and pregnant women. In addition, reports from independent institutions were considered for assessing the adverse effects of phthalates.
According to the CPSC’s health staff, in order for a substance to be considered hazardous, it must be determined toxic under the Federal Hazardous Substances Act (FHSA), which suggests that it is a high-risk substance and the method of exposure is of concern. Companies are given guidelines to abide by the FHSA. In one study [38], phthalates such as BBP, DBP, DEHP, and DiBP were administered to rats to see the effects of exposure. The results showed that testosterone production decreased with 20% of the top dose, and when 40% of the top dose was administered, researchers noticed significant changes in maternal body weight gain, total resorptions, and fetal mortality [38]. However, even though there are several reports about the toxicity and high exposure of phthalates in rats, there are no reports that conclusively show health effects on humans.
The CPSC [39] has restricted five phthalates from teething rings and pacifiers to 0.1%. Di-n-hexyl phthalate, di-n-pentyl phthalate, dicyclohexyl phthalate, diisobutyl phthalate, and diisononyl phthalate (DINP) are the phthalates that were under question for endocrine disruption. In response to the ban, the American Chemistry Council (ACC) stated, “This vote to ban DINP is arbitrary and capricious and proves CPSC isn’t interested in acting based on valid scientific standards.”[39] This response demonstrates that the evidence supporting the ban of DINP is not substantial. According to the ACC in an article by Erickson [40] the risk assessment used by the CPSC relies on bio monitoring data from 2005 to 2006, which shows higher phthalate exposure data than is shown in more recent data. Also, the restrictions of phthalates by the CPSC are created based on antiandrogenic effects. Even if a phthalate is below a level of concern, it is still considered to be contributing to the overall risk of antiandrogenic health effects.
According to the CPSC’s health staff, in order for a substance to be considered hazardous, it must be determined toxic under the Federal Hazardous Substances Act (FHSA), which suggests that it is a high-risk substance and the method of exposure is of concern. Companies are given guidelines to abide by the FHSA. In one study [38], phthalates such as BBP, DBP, DEHP, and DiBP were administered to rats to see the effects of exposure. The results showed that testosterone production decreased with 20% of the top dose, and when 40% of the top dose was administered, researchers noticed significant changes in maternal body weight gain, total resorptions, and fetal mortality [38]. However, even though there are several reports about the toxicity and high exposure of phthalates in rats, there are no reports that conclusively show health effects on humans.
The CPSC [39] has restricted five phthalates from teething rings and pacifiers to 0.1%. Di-n-hexyl phthalate, di-n-pentyl phthalate, dicyclohexyl phthalate, diisobutyl phthalate, and diisononyl phthalate (DINP) are the phthalates that were under question for endocrine disruption. In response to the ban, the American Chemistry Council (ACC) stated, “This vote to ban DINP is arbitrary and capricious and proves CPSC isn’t interested in acting based on valid scientific standards.”[39] This response demonstrates that the evidence supporting the ban of DINP is not substantial. According to the ACC in an article by Erickson [40] the risk assessment used by the CPSC relies on bio monitoring data from 2005 to 2006, which shows higher phthalate exposure data than is shown in more recent data. Also, the restrictions of phthalates by the CPSC are created based on antiandrogenic effects. Even if a phthalate is below a level of concern, it is still considered to be contributing to the overall risk of antiandrogenic health effects.
U.S. FDA Stance on Phthalates
According to the U.S. Food and Drug Administration (FDA) website, the agency is mainly concerned with the use of phthalates in cosmetic products such as make-up, hair spray, nail polish, soap, perfume, and aftershave. The main phthalates in cosmetics have historically been DBP, DMP, and DEP [41]. However, due to the lack of evidence linking phthalates to human reproductive health, the FDA does not have a legal foundation to restrict phthalate use and currently only monitors the levels of phthalates in products and provide feedback to companies.
In a 2012 report [41], the FDA provided a recommended course of action for members of the cosmetics industry regarding phthalate use, focusing on the use of DBP and DEHP as inactive ingredients in consumer products. Based on the large amount of research connecting these phthalates to developmental problems and reproductive toxicity in rodents, the agency recommended that companies avoid using DBP or DEHP in any cosmetics. The report also highlighted that there are safer alternatives to phthalates and urged companies to consider using them.
In a 2012 report [41], the FDA provided a recommended course of action for members of the cosmetics industry regarding phthalate use, focusing on the use of DBP and DEHP as inactive ingredients in consumer products. Based on the large amount of research connecting these phthalates to developmental problems and reproductive toxicity in rodents, the agency recommended that companies avoid using DBP or DEHP in any cosmetics. The report also highlighted that there are safer alternatives to phthalates and urged companies to consider using them.
The followings are the summary about the known phthalate restrictions in articles and consumer products in EU, USA, and other countries.
|
Country |
Substance |
Limit (by weight) |
Conditions of restriction |
|
European Union: |
DEHP DBP BBP DIBP |
DEHP+DBP+BBP<=0.1% |
The plasticized material in toys and childcare articles. (DIBP can be used only with Authorization.) |
|
European Union: |
DINP DIDP DNOP |
DINP+DIDP+DNOP<=0.1% |
The plasticized material in toys and childcare articles which can be placed in the mouth by children. |
|
European Union: |
DEHP DBP BBP DIBP |
DEHP<=0.1% |
All electrical and electronic equipment: 22 July 2019. Category 8 (medical devices) and Category 9 (monitoring and control equipment): 22 July 2021. |
|
USA: |
DEHP DBP BBP |
DEHP<=0.1% |
Children's toys and childcare articles for children under 3. |
|
DINP
DIDP DNOP |
DINP<=0.1% |
All three phthalates are interim banned, so the restriction is applied to children's toy that only can be placed in a child's mouth and childcare articles. |
|
|
Japan: |
DEHP DBP BBP |
DEHP<=0.1% |
Synthetic resin, mainly composed of PVC, for children’s toys. |
|
DINP DIDP DNOP |
DINP<=0.1% |
Synthetic resin, mainly composed of PVC, for children’s toys are intended to contact with mouth (excluding pacifiers and teething rings) and the toys intended for children under three. Pacifiers and teething rings without using PVC as raw material. |
|
|
Canada: |
DEHP DBP BBP |
DEHP<=0.1% |
The vinyl in toys and childcare articles. |
|
DINP DIDP DNOP |
DINP<=0.1% |
The vinyl in any part of toys and childcare products that can be placed in mouth for children under 4. |
|
|
Brazil |
DEHP DBP BBP |
DEHP<=0.1% |
All children’s toys and childcare articles for children under 3. |
|
DINP DIDP DNOP |
DINP<=0.1% |
All children’s toys and child care articles that can be placed in children’s mouth. |
|
|
Argentina |
DEHP DBP BBP DINP DIDP DNOP |
DEHP+DBP+BBP<=0.1% |
All children’s toys and childcare articles for children under 3. |
|
DINP+DIDP+DNOP<=0.1% |
All children’s toys and child care articles that can be placed in children’s mouth under 3. |
||
|
Australia/ New Zealand: |
DEHP |
DEHP<=0.1% |
All children’s toys and child care articles that can be placed in children’s mouth under 3. |
Notes:
DEHP: Bis (2-ethylhexyl) phthalate; DBP: Dibutyl phthalate; BBP: Benzyl butyl phthalate; DINP: Di-‘isononyl’ phthalate; DIDP: Di-‘isodecyl’ phthalate; DNOP: Di-n-octyl phthalate;
DIBP: Diisobutyl phthalate
Childcare article: Any product intended to facilitate sleep, relaxation, hygiene, the feeding of children or sucking on the part of children.
References
Most phthalates used in electronics are low-molecular weight ortho-phthalates that have been shown to have serious health effects, and as a result are becoming regulated. CALCE has been being interested in the performance and reliability of newly alternative materials, which are aligned to the legislations, and proposed potential alternatives to phthalate plasticizers, including bio-based substitutes and thermoplastic elastomers.
CALCE has been working on the health and environement concerns as well as the Legialation related to electronic materials for many years. Some researches on the compliance in safety- and reliability-critical electronics as well as the exemption from RoHS restrictions are published by Professor Michael Pecht. This website is built mainly by the recent paper published by Prof. Pecht, which is “Phthalates in electronics: The risks and the alternatives”. To find more information about the aforementioned publications and other related articles, please refer to the following summarized references.
- M. Pecht, I. Ali, and A. Carlson,"Phthalates in electronics: The risks and the alternatives," IEEE Access, Vol. PP, No. 99, pp. 1-13, 2017.
- E. George and M. Pecht, “RoHS compliance in safety and reliability critical electronics,” Microelectronics Reliability, Vol. 65, pp. 1-7, 2016.
- M. Pecht, T. Shibutani, and L. Wu, “A reliability assessment guide for the transition planning to lead-free electronics for companies whose products are RoHS exempted or excluded,” Microelectronics Reliability, Vol. 62, pp 113-123, 2016, DOI:10.1016/j.microrel.2016.03.020.
- S. Menon, E. George, M. Osterman, and M. Pecht, “High lead (over 85 %) solder in the electronics industry: RoHS exemptions and alternatives,” Journal of Materials Science: Materials in Electronics, Vol. 26, No. 6, pp. 4021-4030, 2015, DOI: 10.1007/s10854-015-2940-4
- M. Pecht, Y. Fukuda and S. Rajagopal, “The impact of lead-free legislation exemptions on the electronics industry,” IEEE Transactions on Electronics Packaging Manufacturing, Vol. 27, No. 4, pp. 221-232, 2004, DOI: 10.1109/TEPM.2004.843150.
Many articleas have been addressing the concerns with phthalates on the health and environment because some phthalates have been considered to affect hormone receptor proteins and enzymes, which are involved in the synthesis or activation of hormones. Some of the articles addressed on the concerns with health and environments about the leakage of phthalates Others were focused on the migration from phthalates-contained to non-phthalates and updating restrictions on the phthalates. The articles are categorized by various topics, and the number in the square bracket ahead the authors for each article represents the reference number cited in this website.
Studies on the migration and new restrictions on the phthalates
[4] P. Ventrice, D. Ventrice, E. Russo, and G. De Sarro, "Phthalates: European regulation, chemistry, pharmacokinetic and related toxicity. Environmental Toxicology and Pharmacology," Vol. 36, No. 1, pp. 88-96, 2013.
[10] S. Gärtner, M. Balski, M. Koch, and I. Nehls, “Analysis and migration of phthalates in infant food packed in recycled paperboard,” Journal of Agricultural and Food Chemistry, Vol. 57, No. 22, pp. 10675-10681, 2009.
[39] C. Hogue, “U.S. to restrict five phthalates in children’s products,” Chemical & Engineering News Global Enterprise, Vol. 95, No. 43, p. 13, 2017.
[48] B. E. Erickson, “European Union further restricts four phthalates,” Chemical & Engineering News Global Enterprise, Vol. 95, No. 26, p. 15, 2017.
Studies on the concerns with health and environments about the phthalates
[2] D. Liang, T. Zhang, H. Fang, and J. He, "Phthalates biodegradation in the environment," Applied Microbiology and Biotechnology, Vol. 80, No. 2, pp. 183-198, 2008.
[6] H. Frederiksen, N. Skakkebaek, and A. Andersson, "Metabolism of phthalates in humans," Molecular Nutrition & Food Research, Vol. 51, No. 7, pp. 899-911, 2007.
[11] K. Boisen, M. Kaleva, K. Main, H. Virtanen, A. Haavisto, I. Schmidt, M. Chellakooty, I. Damgaard, C. Mau, M. Reunanen, N. Skakkebaek, and J. Toppari, "Difference in prevalence of congenital cryptorchidism in infants between two Nordic countries," The Lancet, Vol. 363, No. 9417, pp. 1264-1269, 2004.
[12] E. Huyghe, P. Plante, and P. Thonneau, "Testicular Cancer Variations in Time and Space in Europe," European Urology, Vol. 51, No. 3, pp. 621-628, 2007.
[13] R. Preikša, B. Žilaitienė, V. Matulevičius, N. Skakkebæk, J. Petersen, N. Jørgensen, and J. Toppari, "Higher than expected prevalence of congenital cryptorchidism in Lithuania: a study of 1204 boys at birth and 1 year follow-up," Human Reproduction, Vol. 20, No. 7, pp. 1928-1932, 2005.
[14] K. Boisen, M. Chellakooty, I. Schmidt, C. Kai, I. Damgaard, A. Suomi, J. Toppari, N. Skakkebaek, and K. Main, "Hypospadias in a Cohort of 1072 Danish Newborn Boys: Prevalence and Relationship to Placental Weight, Anthropometrical Measurements at Birth, and Reproductive Hormone Levels at Three Months of Age," The Journal of Clinical Endocrinology & Metabolism, Vol. 90, No. 7, pp. 4041-4046, 2005.
[15] N. Skakkebaek, N. Jorgensen, K. Main, E. Meyts, H. Leffers, A. Andersson, A. Juul, E. Carlsen, G. Mortensen, T. Jensen, and J. Toppari, "Is human fecundity declining?" International Journal of Andrology, Vol. 29, No. 1, pp. 2-11, 2006.
[16] L. Dewalque, C. Charlier, and C. Pirard, "Estimated daily intake and cumulative risk assessment of phthalate diesters in a Belgian general population," Toxicology Letters, Vol. 231, No. 2, pp. 161-168, 2014.
[17] A. Martino-Andrade and I. Chahoud, "Reproductive toxicity of phthalate esters," Molecular Nutrition & Food Research, Vol. 54, No. 1, pp. 148-157, 2010.
[18] A. Schecter, M. Lorber, Y. Guo, Q. Wu, S. H. Yun, K. Kannan, L. S. Birnbaum, "Phthalate Concentrations and Dietary Exposure from Food Purchased in New York State," Environmental Health Perspectives, Vol. 121, No. 4, pp. 473-479, 2013.
[19] W. Wang, X. Xu, and C. Fan, "Health hazard assessment of occupationally di-(2-ethylhexyl)-phthalate-exposed workers in China," Chemosphere, Vol. 120, pp. 37-44, 2015.
[20] R. A. Rudel, D. E. Camann, J. D. Spengler, L. R. Korn, and J. G. Brody, “Phthalates, alkylphenols, pesticides, polybrominated diphenyl ethers, and other endocrine-disrupting compounds in indoor air and dust,” Environmental Science & Technology, Vol. 37, No. 20, pp. 4543-4553, 2003.
[21] S. K. Ritter, “Phthalates’ structural truths,” Chemical & Engineering News Archive, Vol. 93, No. 25, pp. 19-20, 2015.
[23] L. Gray, J. Ostby, J. Furr, M. Price, D. N. Veeramachaneni, and L. Parks, "Perinatal exposure to the phthalates DEHP, BBP, and DINP, but Not DEP, DMP, or DOTP, alters sexual differentiation of the male rat," Toxicological Sciences, Vol. 58, No. 2, pp. 350-365, 2000.
[24] S. Sivaramanan, "E-Waste Management, Disposal and Its Impacts on the Environment," Universal Journal of Environmental Research & Technology, Vol. 3, No. 5, pp. 1-7, 2013.
[25] K. Brigden, J. Webster, I. Labunska, and D. Santillo, "Toxic Chemicals in Computers Reloaded," Greenpeace, 2007.
[26] L. Patton, "CPSC Staff toxicity review of 17 phthalates," United States Consumer Product Safety Commission, 2016.
[27] U.S. Food and Drug Administration, "Ingredients – Phthalates," Center for Food Safety and Applied Nutrition, 2016.
[28] S. Nordbrand, "Out of Control: E-waste trade flows from the EU to developing countries," SwedWatch, 2009.
[29] W. Liu, C. Shen, Z. Zhang, and C. Zhang, "Distribution of Phthalate Esters in Soil of E-Waste Recycling Sites from Taizhou City in China. Bulletin of Environmental Contamination and Toxicology," Vol. 82, No. 6, pp. 665-667, 2009.
[30] A. Saoji, "E-waste management: an emerging environmental and health issue in India," National journal of medical research, Vol. 2, No. 1, pp. 107-110, 2012.
[32] American Chemical Society, “Phthalates in Sediments,” Environmental Science & Technology, Vol. 29, No. 12, p. 535A, 1995.
[33] Z. Xie, R. Ebinghaus, C. Temme, R. Lohmann, A. Caba, and W. Ruck, “Occurrence and air−sea exchange of phthalates in the arctic,” Environmental Science & Technology, Vol. 41, No. 13, pp. 4555-4560, 2007.
[34] J. Ejlertsson, M. Alnervik, S. Jonsson, and B. H. Svensson, “Influence of water solubility, side-chain degradability, and side-chain structure on the degradation of phthalic acid esters under methanogenic conditions,” Environmental Science & Technology, Vol. 31, No. 10, pp. 2761-2764, 1997.
[36] B. Hileman, “Phthalates in toys,” Chemical & Engineering News Archive, Vol. 82, No. 40, p. 11, 2004.
[40] B. Erickson, "Regulators and Retailers Raise Pressure on Phthalates," Chemical & Engineering News, Vol. 93, No. 25, p. 11-15, 2015.
[47] G. Sadeghi, E. Ghaderian, and A. O'Connor, "Determination of Dioctyl phthalate (DEHP) concentration in polyvinyl chloride (PVC) plastic parts of toothbrushes," The Downtown Review, Vol. 1, No. 2, n/a, 2015.
Studies on the possible alternatives for the phthalates
[5] M. Benaniba and V. Massardier-Nageotte, "Evaluation effects of biobased plasticizer on the thermal, mechanical, dynamical mechanical properties, and permanence of plasticized PVC," Journal of Applied Polymer Science, Vol. 118, No. 6, pp. 3499-3508, 2010.
[7] Lowell Center for Sustainable Production, "Phthalates and Their Alternatives: Health and Environmental Concerns," University of Massachusetts, 2011.
[22] N. Kambia, A. Farce, K. Belarbi, B. Gressier, M. Luyckx, P. Chavatte, and T. Dine, "Docking study: PPARs interaction with the selected alternative plasticizers to di(2-ethylhexyl) phthalate," Journal of Enzyme Inhibition and Medicinal Chemistry, Vol. 31, No. 3, pp. 448-455, 2016.
[42] A. Lindström and M. Hakkarainen, "Environmentally friendly plasticizers for poly(vinyl chloride)—Improved mechanical properties and compatibility by using branched poly(butylene adipate) as a polymeric plasticizer," Journal of Applied Polymer Science, Vol. 100, No. 3, pp. 2180-2188, 2006.
[43] J. Kuczynski and D. Boday, "Bio-based materials for high-end electronics applications," International Journal of Sustainable Development & World Ecology, Vol. 19, No. 6, pp. 557-563, 2012.
[44] Teknor Apex, "Thermoplastic Elastomers: The Softest Materials Solving Your Hardest Problems," Teknor Apex, 2016.
[45] J. Kutka, "Thermoplastic Elastomer (TPE) Market Growth Continues," Machine Design, 2009.
[46] Y. Chen, A. Kushner, G. Williams, and Z. Guan, "Multiphase design of autonomic self-healing thermoplastic elastomers," Nature Chemistry, Vol. 4, No. 6, pp. 467-472, 2012.
Environmental health reports from the companies and international institutes
[1] Greenpeace, "The dangerous chemicals in electronic products," Greenpeace, 2016.
[3] ECPI, "Orthophthalates," 2014.
[8] Apple, "Environmental Responsibility Report: 2016 Progress Report," Covering Fiscal Year 2015. Apple, 2016.
[9] M. Cobbing and T. Dowdall, "Green Gadgets: Designing the Future-The path to greener electronics," Greenpeace International, 2014.
[31] J. Puckett, E. Hopson, and M. Huang, "Disconnect: Goodwill and Dell, Exporting the Public’s E-Waste to Developing Countries," Basel Action Network, 2016.
[35] European Commission, "RoHS Amendment adding Phthalates to Restricted Substances is Published," European Commission, 2016.
[37] L. Patton, "Toxicity Review of two less common phthalates and one phthalate alternative for the CHAP," United States Consumer Product Safety Commission, 2011.
[38] L. Patton, "CPSC Staff toxicity review of 17 phthalates," United States Consumer Product Safety Commission, 2011.
[41] U.S. Food and Drug Administration, "Guidance for industry limiting the use of certain phthalates as excipients in CDER-regulated products," The Administration, 2012.
Contact
For questions or concerns regarding phthalates or CALCE's research into phthalate safety and alternatives, contact Professor Michael Pecht:
301-405-5323 | pecht@calce.umd.edu
Top