the stick, the stone and the puddle

based on yesterday’s post, today i’ll spent some time on phthalates. this is a group of chemicals used to soften and make plastics more flexible and durable. they are often called ‘plasticizers’. some quick general information can be found on the following sites: wikipedia, canadian cancer society, environmental working group (seems to me like an activist site), and many more. don’t be afraid to google the word if you want more information. as i said before, this is a group of particular compounds, so there’s more than one type of phthalate. a list of most common types of phthalates used is found on wikipedia. keep in mind though, chemical compounds most often have synonyms (or aliases).

why should we be concerned about these? well, phthalates are known to cause tumors and other abnormalities in livers of rats and mice (see canadian cancer society website). furthermore the EPA (Environmental Protection Agency) has classified some phthalates (Di (2-ethylhexyl)phthalate or DEHP) as ‘probable human carcinogens’. phthalates are known endocrine-disruptors in rodents (animal studies). animal fetal adverse effects have been noticed (specifically to di-butyl phthalate). fetal exposure occured through exposure to the mother. some of the effects on the male fetus include: decreas testosteron production, reduce sperm production and other problems with the reproductive system. other studies have reported association between exposure to some phthalates (monobenzyl- and mono-isobutyl phthalate) and small genital size in male off-springs. other abnormalities have been reported in rodent studies (growth of extra ribs in off-springs due to exposure to the mother) with exposure to higher levels. some human studies have been reported, and for the most part they tend to agree with animal study results, however…keep in mind the data on human exposure and effects is a bit scarced. associations have been noticed between mother levels of phthaltes in urine and effects in off-springs; however, association does not imply causation. there are currently cohort studies going on in the united states in regards to exposure of phthalates to pregnant women; so at some point these results will be available.

exposure of the population occurs to many consumer products, such as, but not limited to: clothing, pharmaceuticals, cosmetics, children’s toys, glow sticks, building materials, lubricants, food packaging, etc. i haven’t placed these in any particular order. keep in mind, you shouldn’t jump off your seat and over-react. these chemicals are present, but you must realize that just because they are in the environment it does not necessarily mean they enter our body. the concern is, when they do enter and which products increase our potential exposure. there are various pathways of exposure, and they include: ingestion, inhalation, skin absorption and potentially intravenous injection.

exposure by injestion occurs if you put them in your mouth, meaning it mostly happens through food. however, these plasticizers are present in children toys…so if you baby likes to place his/her toys in her mouth…this is a potential pathway. food exposure, is reported to probably be the largest pathway of exposure to these compounds, however the levels vary with foods. the united states and canada are looking into exposure, studies are happening and they are looking to regulate it (i’m not sure of europe as i didn’t have time to look into that…).

inhalation exposure is possible if these compounds become airborne (either gas phase, or as part of dust). baking of polymer clays will cause these plasticizers to become airborne…which will increase potential inhalation. there have been reports of phthalates being present in household dust and working environment dust (office). however, there have been some reports that reported no correlation between household dust concentration to one particular phthalate (DEHP) and urine concentration in boys of that particular phthalate or its metabolites.

skin absorption can essentially occur if one comes into contact with these compounds through the skin. that’s where the cosmetics come in. cosmetic products (ranging from: sunscreens, personal care products, make-up, etc.) have been reported to contain phthalates. although in canada manufacturers are required to state the ingredients, this may not happen all the time. products brought in from other countries by the consumer may not meet these regulations. a report from 2005 (from the united states) stated that about 70% of the cosmetic products they purchased from the store contained phthalates, yet this was not identified on the label. the products included in them were: deodorants, fragrances, hair gels, mousses, hair sprays, hand and body lotions, nail polish. however, it’s great to see canada is taking a leader role and pushing for the ingredient list…

absorption depends on the following factors: concentration of phthalates in the product, lenght of time the product is in contact with the skin, solubility of particular phthalate (remember, just because it’s in the same class it does not mean it acts or behaves the same), chemical structure. it also depends on the place where the body comes into contact with the products, as for example the face, axilia and scrotum have an absorption 10 times higher than the absorption rate of the arm skin. some studies have estimated the rate of absorption through skin to phthalates, and overall the permeable rate is low. however…the longer the contact…the more will be absorbed.

furthermore, levels of various phthalates have been detected in the urine of pregnant women as well as in the breast milk (i can just hear one of my profs asking me to state the level and not simply say levels have been found. however…if anyone is interested in levels i’ll be more than happy to state them). at this point, there are still large data gaps: outdated diet exposure levels, a dose-response relationship has not been determined (not to my current knowledge), contribution of dermal exposure to overall exposure is not yet quantified, fetal exposure is known to potentially cause problems, but causation is yet to be established. given all these data gaps, it is quite hard to estimate or guess if the human levels to phthalates reported in humans are of concern, better yet of great concern at this point.

what can you do about if you’re concern about absorption through skin from cosmetics? well…look at the factors that contribute to skin absorbance and see which ones you can control. reduce time you wear the cosmetics, if they are not required, and see how much is need to get the desired effect (soften skin, etc.).

dietary intake, which is thought to be the major pathway of exposure to these compounds…keep an eye on the ingredients (even though given some of the regulations…some products will not have a list of ingredients). phthalates are used in plastic manufacturing…so if you’re afraid of it leaching (similar story to bisphenol A), then reduce usage of plastic containers or bottles…

word of caution, no need to over-react at this point. however, it’s worth it to stay informed and look up information about the products you use.