Reproductive and developmental toxicity of phthalates

Analysis of phthalic acid diesters, monoester, and other plasticizers in polyvinyl chloride household products in Japan

The aim of this study was to determine the concentrations of six phthalic acid diesters (PAEs) [di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), diisononyl phthalate (DINP), di-n-octyl phthalate (DNOP), and diisodecyl phthalate (DIDP)], two non-phthalic plasticizers [di(2-ethylhexyl) adipate (DEHA), 2,2,4-trimethyl-1,3-pentanediol diisobutylate (TMPDIB)], and mono 2-ethylhexyl phthalate(MEHP) in polyvinyl chloride (PVC) household products that children often places in their mouths and/or contact with their skin (41 products, 47 samples) in Japan. The detection frequencies of the studied compounds were as follows: DEHP (79 %), DINP-2 (13 %), DINP-1 (11 %), DBP (8.5 %), DEHA (8.5 %), DIDP (4.3 %), and DNOP (2.1 %). Concentrations of these compounds ranged from 0.021 % to 48 %. BBP and TMPDIB were not detected in the all samples. Most samples contained DEHP and DINP at high concentrations over 0.1 %. High concentrations of PAEs were detected in PVC household products that appear appealing to children and can possibly be licked and chewed by them. Di(2-ethylhexyl) terephtalete, diisononyl 1,2-cyclohexanedicarboxylic acid, acetyl tributyl citrate, and di(2-ethylhexyl) 4-cyclohexene-1,2-dicarboxylate used as substitute plasticizers were also detected in several samples. MEHP was present in 70 % of the samples, with concentrations ranging from trace amounts to 140 μg/g. The ratios of MEHP against DEHP were 6.2 × 10(-4) to 1.6 × 10(-1) %. MEHP in the household products investigated in this study was most probably an impurity in DEHP. The high concentrations of PAEs detected in products that children often place in their mouth reveal the importance of replacing plasticizers in common household products, and not just children's toys, with safer alternatives.

Prenatal exposure to phthalate esters and PAHs and birth outcomes

The purpose of this study was to investigate the relationship between the levels of prenatal exposure to phthalate ester and PAHs and birth outcomes among 149 Japanese pregnant women. Urinary concentrations of 9 phthalate ester metabolites, mono methyl phthalate (MMP), mono ethyl phthalate (MEP), mono-n-butyl phthalate (MnBP), mono benzyl phthalate (MBzP), mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), mono-iso-nonyl phthalate (MINP) and mono-n-octyl phthalate (MnOP) and PAHs metabolite (1-hydroxypyrene, 1-OHP) were analyzed in spot urine samples collected from pregnant women. Correlation analysis and multiple regression analysis were conducted between the concentrations of maternal urinary metabolites and birth outcomes such as birth weight, birth length, head circumference and gestational age. Creatinine-corrected concentration (geometric mean; microg/g cre) was 9.14 (MMP), 9.76 (MEP), 51.6 (MnBP), 5.62 (MBzP), 5.45 (MEHP), 10.6 (MEHHP), 11.3 (MEOHP), 0.031 (MINP), 0.025 (MnOP) and 0.121 (1-OHP). These concentrations are comparable with literature value. The relationships between prenatal exposure to phthalate esters and birth outcomes were not significant. Statistically significant negative correlation was observed between 1-OHP and birth weight, birth length and head circumstances although the correlation was insignificant when only non-smokers were included in multiple regression analysis. In conclusion, we found that prenatal exposure to phthalate esters or PAHs did not affect birth outcomes at the exposure level of the present subjects.

An assessment of the ability of phthalates to influence immune and allergic responses

It has been suggested that one possible contributor to the increasing prevalence of atopic (IgE-mediated) allergic diseases and asthma in Europe and the US is exposure to chemicals that may act as adjuvants. Certain commonly used phthalate plasticisers, such as di-(2-ethylhexyl) phthalate, have been implicated in this regard. The evidence for the ability of phthalates to impact on immune and allergic responses has been examined, encompassing epidemiological investigations and results deriving from studies using experimental animals and from analyses in vitro. The epidemiological data provide some evidence that exposure to phthalates may be associated with increased risk of development of allergies and asthma, however, the lack of objective exposure information limits the interpretation. A variety of studies have been performed in mice to examine the influence of phthalate (delivered via various routes of exposure) to impact on immune responses. Measurement of antibody responses is the commonest read out, although other parameters of inflammation such as eosinophil infiltration and cytokine production have been used also. Although certain phthalates, when delivered at appropriate doses, and via an appropriate route, have been reported to impact on immune and inflammatory function in rodents, as yet no consistent pattern has emerged. Results ranged from potentiation of immune or inflammatory responses, to the absence of any effect, to inhibitory or immunosuppressive activity. In addition, comparatively low doses of phthalates have been associated with immune effects only when routes of administration (subcutaneous or intraperitoneal) are used that do not reflect, and are much less relevant for, opportunities for human contact with phthalates. There is clearly a case to be made for the design of more definitive animal studies that will allow development of a more detailed understanding of whether and to what extent, and under what conditions, phthalates are able to effect meaningful changes in immune function that may in turn impact on human health.