this to be established, the polymer must be heated in the presence of the plasticizer, first above the tg of the polymer and then into a melt state. this enables an intimate mix of polymer and plasticizer to be formed, and for these interactions to occur. when cooled, these interactions remain and the network of pvc chains cannot reform (as is present in unplasticized pvc, or pvc-u). the alkyl chains of the phthalate then screen the pvc chains from each other as well. they are blended within the plastic article as a result of the manufacturing process. because they are not chemically bonded to the host plastics, phthalates are released from the plastic article by relatively gentle means. for example, they can be removed by heating or by extraction with organic solvents. alternatives market trend in decreasing use of low orthophthalates including dehp being inexpensive, nontoxic (in an acute sense), colorless, noncorrosive, biodegradable, and with easily tuned physical properties, phthalate esters are nearly ideal plasticizers. among the numerous alternative plasticizers are dioctyl terephthalate (deht) (a terephthalate isomeric with dehp) and 1,2-cyclohexane dicarboxylic acid diisononyl ester (dinch) (a hydrogenated version of dinp). both deht and dinch have been used in high volumes for a variety of products used in contact with humans as alternative plasticizers for dehp and dinp. some of these products include medical devices, toys, and food packaging. deht and dinch are more hydrophobic than other phthalate alternatives such as bis(2-ethylhexyl) adipate (deha) and diisodecyl adipate (dida). since alternative plasticizers such as deht and dinch are more likely to bind to organic matter and airborne particles indoors, exposure occurs primarily through food consumption and contact with dust. many bio-based plasticizers based on vegetable oil have been developed. they can be substituted for dehp. environmental impact phthalates are easily released into the environment. in general, they do not persist due to rapid biodegradation, photodegradation, and anaerobic degradation. outdoor air concentrations are higher in urban and suburban areas than in rural and remote areas. they also pose no acute toxicity. because of their volatility, dep and dmp are present in higher concentrations in air in comparison with the heavier and less volatile dehp. higher air temperatures result in higher concentrations of phthalates in the air. pvc flooring leads to higher concentrations of bbp and dehp, which are more prevalent in dust. a 2012 swedish study of children found that phthalates from pvc flooring were taken up into their bodies, showing that children can ingest phthalates not only from food but also by breathing and through the skin. diet is believed to be the main source of dehp and other phthalates in the general population. fatty foods such as milk, butter, and meats are a major source. studies show that exposure to phthalates is greater from ingestion of certain foods, rather than exposure via water bottles as is most often first thought of with plastic chemicals. low-molecular-weight phthalates such as dep, dbp, bbzp may be dermally absorbed. inhalational exposure is also significant with the more volatile phthalates. another study, conducted between 2003 and 2010 analysing data from 9,000 individuals, found that those who reported that they had eaten at a fast food restaurant had much higher levels of two separate phthalates—dehp and dinp—in their urine samples. even small consumption of fast food caused higher presence of phthalates. "people who reported eating only a little fast food had dehp levels that were 15.5 percent higher and dinp levels that were 25 percent higher than those who said they had eaten none. for people who reported eating a sizable amount, the increase was 24 percent and 39 percent, respectively." in a 2008 bulgarian study, higher dust concentrations of dehp were found in homes of children with asthma and allergies, compared with healthy children's homes. the author of the study stated, "the concentration of dehp was found to be significantly associated with wheezing in the last 12 months as reported by the parents." phthalates were found in almost every sampled home in bulgaria. the same study found that dehp, bbzp, and dnop were in significantly higher concentrations in dust samples collected in homes where polishing agents were used. data on flooring materials was collected, but there was not a significant difference in concentrations between homes where no polish was used that have balatum (pvc or linoleum) flooring and homes with wood. high frequency of dusting did decrease the concentration. in general, children's exposure to phthalates is greater than that of adults. in a 1990s canadian study that modeled ambient exposures, it was estimated that daily exposure to dehp was 9 μg/kg bodyweight/day in infants, 19 μg/kg bodyweight/day in toddlers, 14 μg/kg bodyweight/day in children, and 6 μg/kg bodyweight/day in adults. infants and toddlers are at the greatest risk of exposure, because of their mouthing behavior. body-care products containing phthalates are a source of exposure for infants. the authors of a 2008 study "observed that reported use of infant lotion, infant powder, and infant shampoo were associated with increased infant urine concentrations of , and this association is strongest in younger infants. these findings suggest that dermal exposures may contribute significantly to phthalate body burden in this population." although they did not examine health outcomes, they noted that "young infants are more vulnerable to the potential adverse effects of phthalates given their increased dosage per unit body surface area, metabolic capabilities, and developing endocrine and reproductive systems." infants and hospitalized children are particularly susceptible to phthalate exposure. medical devices and tubing may contain 20–40% di(2-ethylhexyl) phthalate (dehp) by weight, which "easily leach out of tubing when heated (as with warm saline / blood)". several medical devices contain phthalates including, but not limited to, iv tubing, gloves, nasogastric tubes, and respiratory tubing. the food and drug administration did an extensive risk assessment of phthalates in the medical setting and found that neonates may be exposed to five times greater than the allowed daily tolerable intake. this finding led to the conclusion by the fda that, "hildren undergoing certain medical procedures may represent a population at increased risk for the effects of dehp". in 2008, the danish environmental protection agency (epa) found a variety of phthalates in erasers and warned of health risks when children regularly suck and chew on them. the european commission scientific committee on health and environmental risks (scher), however, considers that, even in the case when children bite off pieces from erasers and swallow them, it is unlikely that this exposure leads to health consequences. phthalates are also found in medications, where they are used as inactive ingredients in producing enteric coatings. it is not known how many medications are made using phthalates, but some include omeprazole, didanosine, mesalamine, and theophylline. a recent study found that urinary concentrations of monobutyl phthalate, the dbp metabolite, of asacol (a particular formulation of mesalamine) users was 50 times higher than the mean of nonusers. the study showed that exposures from phthalate-containing medications can far exceed population levels from other sources. dbp in medications raises concern about health risks due to the high level of exposures associated with taking these medications, especially in vulnerable segments of the population, including pregnant women and children. in 2008, the united states national research council recommended that the cumulative effects of phthalates and other antiandrogens be investigated. it criticized u.s. epa guidances, which stipulate that, when examining cumulative effects, the chemicals examined should have similar mechanisms of action or similar structures, as too restrictive. it recommended instead that the effects of chemicals that cause similar adverse outcomes should be examined cumulatively. thus, the effect of phthalates should be examined together with other antiandrogens, which otherwise may have been excluded because their mechanisms or structure are different. health effects toy dolls manufactured in china and seized by u.s. customs and border protection in 2013 due to high phthalate levelsa study in the peer-reviewed journal environmental pollution published october 12, 2021 found that high phthalate levels are weakly correlated with a greater risk of dying from any cause and with a stronger correlation to dying from heart problems, but the calculated hazard ratios were below 2 in both cases. the study estimated that phthalates may contribute to 91,000–107,000 premature deaths each year among people aged 55–64 in the united states. endocrine disruption further information: endocrine disruptor § phthalates phthalates enter the bloodstream and disrupt sex hormone production, interfering with sexual development in infants and sexual behaviour in adults. levels of phthalates have been dose-dependently linked to reduced anogenital distance decreased sexual desire and satisfaction in women, and malformed genital development in rats. phthalates act by mimicking the female hormone estrogen, which in turn inhibits production of the male hormone testosterone. as such, phthalates are considered to be endocrine disruptors—a substance that interferes with the normal hormonal mechanisms that allow a biological organism to interact with its environment, and has sparked demands to ban or restrict its use in baby toys. endocrine disruptors exhibit numerous behaviors that can make studying them a challenge. there can be a lag between when someone is exposed to an endocrine disruptor and any symptoms manifesting themselves–in particular fetal and early childhood exposure may have consequences later in adulthood. many studies refer to this period of fetal and postnatal development as particularly important to development, but studying this is difficult; it is obviously a huge challenge to measure endocrine disruptor exposure during fetal development and then decades later diagnosing any health problems. additionally, endocrine disruptor exposure can transmit epigenetically to one's offspring without them being directly exposed to the endocrine disruptors. finally, particularly low levels of exposure may still have significant effects, and exposure to multiple endocrine disruptors across a variety of compounds (not just phthalates) may synergistically combine to cause a greater effect. evaluating the actual effects of a specific compound such as a particular phthalate requires examining cumulative exposure across multiple compounds, rather than evaluating one compound in isolation. a widespread concern about phthalate exposure is the possibility (though not conclusive) that it is the cause of a worldwide drop in male fertility. studies have shown that phthalates cause abnormalities in the reproductive systems of animals, with the greatest effects when the animal is exposed during gestation and immediately thereafter. numerous studies on adult male humans show the similar result that phthalate exposure correlates with worsening metrics of male fertility, such as semen quality, the quantity of damaged dna in sperm, decreased sperm motility, decreased semen volume, and other metrics. phthalates causing harm to the male reproductive system is plausible, and continues to be researched. the effect of phthalates on the female reproductive system is also not fully understood yet. current studies indicate phthalates have negative effects on folliculogenesis and steroidogenesis. early research also shows phthalate exposure may be associated with diabetes and insulin resistance, breast cancer, obesity, metabolic disorders, and immune function. there are possible (though not conclusive) associations between phthalate exposure and adverse child neurodevelopment, including the development of adhd and autistic behaviors and lower cognitive and motor development. most common associations found in medical reports link the phthalates exposure to hyperactivity, aggression, and other adverse behaviors. some studies have found the childhood exposure to be as early as in utero. in many cases, there are studies that show connections between phthalates and these negative outcomes, as well as studies that show no connection; this is likely due to the research challenges outlined above, and when resolved, could show that phthalate exposure does not cause health effects, or even that they have a much greater effect than currently predicted. in all cases, larger studies are needed to demonstrate incontrovertibly what effect phthalate exposure has on human health. a nature reviews endocrinology review paper from 2017 gives some advice for avoiding exposure to phthalates for concerned people; while they make pains to state that there is no evidence that shows this advice will positively affect one's health, they suggest (1) eating a balanced diet to avoid ingesting too many endocrine disruptors from a single source, (2) eliminating canned or packaged food in order to limit ingestion of dehp phthalates leached from plastics, and (3) eliminating use of any personal product such as moisturizer, perfume, or cosmetics that contain phthalates. eliminating personal products containing phthalates can be particularly difficult or impossible due to some countries such