bpa bound into resin or plastic. popular uses of thermal paper include receipts, event and cinema tickets, labels, and airline tickets. a swiss study found that 11 of 13 thermal printing papers contained 8 – 17 g/kg bisphenol a (bpa). upon dry finger contact with a thermal paper receipt, roughly 1 μg bpa (0.2 – 6 μg) was transferred to the forefinger and the middle finger. for wet or greasy fingers approximately 10 times more was transferred. extraction of bpa from the fingers was possible up to 2 hours after exposure. further, it has been demonstrated that thermal receipts placed in contact with paper currency in a wallet for 24 hours cause a dramatic increase in the concentration of bpa in paper currency, making paper money a secondary source of exposure. another study has identified bpa in all of the waste paper samples analysed (newspapers, magazines, office paper, etc.), indicating direct results of contamination through paper recycling. free bpa can readily be transferred to skin, and residues on hands can be ingested. bodily intake through dermal absorption (99% of which comes from handling receipts) has been shown for the general population to be 0.219 ng/kg bw/day (occupationally exposed persons absorb higher amounts at 16.3 ng/kg bw/day) whereas aggregate intake (food/beverage/environment) for adults is estimated at 0.36–0.43 μg/kg bw/day (estimated intake for occupationally exposed adults is 0.043–100 μg/kg bw/day). a study from 2011 found that americans of all age groups had twice as much bpa in their bodies as canadians; the reasons for the disparity were unknown, as there was no evidence to suggest higher amounts of bpa in u.s. foods, or that consumer products available in the u.s. containing bpa were bpa-free in canada. according to another study it may have been due to differences in how and when the surveys were done, because "although comparisons of measured concentrations can be made across populations, this must be done with caution owing to differences in sampling, in the analytical methods used and in the sensitivity of the assays." comparing data from the national health and nutrition examination surveys (nhanes) from four time periods between 2003 and 2012, urinary bpa data the median daily intake for the overall population is approximately 25 ng/kg/day and below current health based guidelines. additionally, daily intake of bpa in the united states has decreased significantly compared to the intakes measured in 2003–2004. public attention and governmental action during this time period may have decreased the exposure to bpa somewhat but these studies did not include children under the age of six. according to the endocrine society, age of exposure is an important factor in determining the extent to which endocrine disrupting chemicals will have an effect, and the effects on developing fetuses or infants is quite different than an adult. fetal and early-childhood exposures a 2009 study found higher urinary concentrations in young children than in adults under typical exposure scenarios. in adults, bpa is eliminated from the body through a detoxification process in the liver. in infants and children, this pathway is not fully developed so they have a decreased ability to clear bpa from their systems. several recent studies of children have found levels that exceed the epas suggested safe limit figure. infants fed with liquid formula are among the most exposed, and those fed formula from polycarbonate bottles can consume up to 13 micrograms of bisphenol a per kg of body weight per day (μg/kg/day; see table below). in the u.s. and canada, bpa has been found in infant liquid formula in concentrations varying from 0.48 to 11 ng/g. bpa has been rarely found in infant powder formula (only 1 of 14). the u.s. department of health & human services (hhs) states that "the benefit of a stable source of good nutrition from infant formula and food outweighs the potential risk of bpa exposure". bpa is present in human breast milk, having been found by several studies in 62–75% of breast milk samples. this is presumably due to the mothers being exposed to bpa since it is not naturally produced by the body. children may be more susceptible to bpa exposure than adults (see health effects). a 2010 study of people in austria, switzerland, and germany has suggested polycarbonate (pc) baby bottles as the most prominent role of exposure for infants, and canned food for adults and teenagers. in the united states, the growing concern over bpa exposure in infants in recent years has led the manufacturers of plastic baby bottles to stop using bpa in their bottles. the fda banned the use of bpa in baby bottles and sippy cups (july 2012) as well as the use of epoxy resins in infant formula packaging. however, babies may still be exposed if they are fed with old or hand-me-down bottles bought before the companies stopped using bpa. one often overlooked source of exposure occurs when a pregnant woman is exposed, thereby exposing the fetus. animal studies have shown that bpa can be found in both the placenta and the amniotic fluid of pregnant mice. since bpa was also "detected in the urine and serum of pregnant women and the serum, plasma, and placenta of newborn infants" a study to examine the externalizing behaviors associated with prenatal exposure to bpa was performed which suggests that exposures earlier in development have more of an effect on the behavior outcomes and that female children (2-years-old) are impacted more than males. a study of 244 mothers indicated that exposure to bpa before birth could affect the behavior of girls at age 3. girls whose mother's urine contained high levels of bpa during pregnancy scored worse on tests of anxiety and hyperactivity. although these girls still scored within a normal range, for every 10-fold increase in the bpa of the mother, the girls scored at least six points lower on the tests. boys did not seem to be affected by their mother's bpa levels during pregnancy. after the baby is born, maternal exposure can continue to affect the infant through transfer of bpa to the infant via breast milk. because of these exposures that can occur both during and after pregnancy, mothers wishing to limit their child's exposure to bpa should attempt to limit their own exposures during that time period. while the majority of exposures have been shown to come through the diet, accidental ingestion can also be considered a source of exposure. one study conducted in japan tested plastic baby books to look for possible leaching into saliva when babies chew on them. while the results of this study have yet to be replicated, it gives reason to question whether exposure can also occur in infants through ingestion by chewing on certain books or toys. population estimated daily bisphenol a intake (μg/kg body weight/day).table adapted from the national toxicology program expert panel report. infant (0–6 months)formula-fed (lower number assumes weight of 4.5 kg and intake of 700 ml/day with maximum concentration of bpa detected in u.s. canned formula; higher number assumes weight of 6.1 kg and intake of 1060 ml/day from powdered formula in cans with epoxy linings and using polycarbonate bottles) 1–11 infant (0–6 months)breast-fed (lower number assumes weight of 6.1 kg and intake of 1060 ml/day with maximum concentration of bpa detected in japanese breast milk samples; higher number assumes weight of 4.5 kg and intake of 700 ml/day with maximum concentration of free bpa detected in u.s. breast milk samples) 0.2–1 infant (6–12 months) 1.65–13 child (1.5–6 years) 0.043–14.7 adult (general population) 0.008–1.5 adult (occupational) 0.043–100 regulation public health regulatory history in the united states charles schumer introduced a 'bpa-free kids act of 2008' to the u.s. senate seeking to ban bpa in any product designed for use by children and require the center for disease control to conduct a study about the health effects of bpa exposure. it was reintroduced in 2009 in both senate and house, but died in committee each time. in 2008, the fda reassured consumers that current limits were safe, but convened an outside panel of experts to review the issue. the lang study was released, and co-author david melzer presented the results of the study before the fda panel. an editorial accompanying the lang study's publication criticized the fda's assessment of bisphenol a: "a fundamental problem is that the current adi for bpa is based on experiments conducted in the early 1980s using outdated methods (only very high doses were tested) and insensitive assays. more recent findings from independent scientists were rejected by the fda, apparently because those investigators did not follow the outdated testing guidelines for environmental chemicals, whereas studies using the outdated, insensitive assays (predominantly involving studies funded by the chemical industry) are given more weight in arriving at the conclusion that bpa is not harmful at current exposure levels." the fda was criticized that it was "basing its conclusion on two studies while downplaying the results of hundreds of other studies." diana zuckerman, president of the national research center for women and families, criticized the fda in her testimony at the fda's public meeting on the draft assessment of bisphenol a for use in food contact applications, that "at the very least, the fda should require a prominent warning on products made with bpa". in march 2009 suffolk county, new york became the first county to pass legislation to ban baby beverage containers made with bisphenol a. by march 2009, legislation to ban bisphenol a had been proposed in both house and senate. in the same month, rochelle tyl, author of two studies used by fda to assert bpa safety in august 2008, said those studies did not claim that bpa is safe, because they were not designed to cover all aspects of the chemical's effects. in may 2009, minnesota and chicago were the first u.s. jurisdictions to pass regulations limiting or banning bpa. in june 2009, the fda announced its decision to reconsider the bpa safety levels. grassroots political action led connecticut to become the first u.s. state to ban bisphenol a not only from infant formula and baby food containers, but also from any reusable food or beverage container. in july 2009, the california environmental protection agency's developmental and reproductive toxicity identification committee in the california office of environmental health hazard assessment unanimously voted against placing bisphenol a on the state's list of chemicals that are believed to cause reproductive harm. the panel was concerned over the growing scientific evidence showing bpa's reproductive harm in animals, found that there was insufficient data of the effects in humans. critics pointed out that the same panel failed to add second-hand smoke to the list until 2006, and only one chemical was added to the list in the last three years. in september, the u.s. environmental protection agency announced that it was evaluating bpa for an action plan development. in october, the nih announced $30,000,000 in stimulus grants to study the health effects of bpa. this money was supposed to result in many peer-reviewed publications. on 15 january 2010, the fda expressed "some concern", the middle level in its scale of concerns, about the potential effects of bpa on the brain, behavior, and prostate gland in fetuses, infants, and young children, and announced that it was taking reasonable steps to reduce human exposure to bpa in the food supply. however, the fda was not recommending that families change the use of infant formula or foods, as it saw the benefit of a stable source of good nutrition as outweighing the potential risk from bpa exposure. on the same date, the department of health and human services released information to help parents to reduce children's bpa exposure. as of 2010 many u.s. states were considering some sort of bpa ban. in june 2010 the 2008–2009 annual report of the president's cancer panel was released and recommended: "because of the long latency period of many cancers, the available evidence argues for a precautionary approach to these diverse chemicals, which include (…) bisphenol a". in august 2010, the maine board of environmental protection voted unanimously to ban the sale of baby bottles and other reusable food and beverage containers made with bisphenol a as of january 2012. in february 2011, the newly elected governor of maine, paul lepage, gained national attention when he spoke on a