Personal exposure to HBCDs and its degradation products via ingestion of indoor dust

Personal exposures via ingestion of indoor dust to α-, β-, and γ-hexabromocyclododecanes (HBCDs) and the degradation products (pentabromocyclododecenes (PBCDs) and tetrabromocyclododecadienes (TBCDs)) were estimated for 21 UK adults. Under an average dust ingestion scenario, personal exposures ranged from 4.5 to 1851 ng ΣHBCDs day^? 1; while the range under a high dust ingestion scenario was 11 to 4630 ng ΣHBCDs day^? 1. On average, personal exposure to ΣHBCDs via dust ingestion in this study was 35% α-, 11% β-, and 54% γ-HBCD. However, while exposure to β-HBCD (4–18% of ΣHBCDs) was relatively consistent with the proportion of this diastereomer in the HBCD commercial formulation; exposures to α- and γ-isomers (11–58% and 29–82% of ΣHBCDs respectively) showed substantial variation from the commercial formulation pattern. Personal exposures to ΣTBCDs (median = 0.2 ng day^? 1 under an average dust ingestion scenario) and ΣPBCDs (1.4 ng day^? 1) were significantly lower (p < 0.05) than for ΣHBCDs (48 ng day^? 1). Despite this, the exposure of one participant to ΣPBCDs exceeded the exposure to ΣHBCDs received by 85% of the other participants. On average, house dust provided the major contribution to personal exposure via dust ingestion to all target compounds due to the large time fraction spent in houses. In contrast, although participants spent less time in cars than in offices, car dust makes a higher average contribution (17%) to ΣHBCDs exposure than office dust (13%).     

Tri-decabrominated diphenyl ethers and hexabromocyclododecane in indoor air and dust from Stockholm microenvironments 2: indoor sources and human exposure

Data on polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) concentrations from Stockholm, Sweden, indoor microenvironments were combined with information from detailed questionnaires regarding the sampling location characteristics, including furnishing and equipment present. These were used to elucidate relationships between possible flame-retarded sources and the contaminant concentrations found in air and dust. Median concentration ranges of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD from all microenvironments were 19-570, 1.7-280, 29-3200 and < 1.6-2 pg/m³ in air and 22-240, 6.1-80, 330-1400 and 45-340 ng/g in dust, respectively. Significant correlations were found between concentrations of some PBDEs and HBCD in air and/or dust and the presence of electronic/electrical devices, foam furniture, PUF mattresses and synthetic bed pillows in, as well as floor area and construction year of the microenvironment. Car interiors were a source to indoor air in dealership halls. Using median and maximum concentrations of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD in air and dust, adult and toddler (12-24 months) intakes from inhalation and dust ingestion were estimated. Toddlers had higher estimated intakes of ΣPenta-, ΣDecaBDE and HBCD (7.8, 43, 7.6 ng/d, respectively) from dust ingestion than adults (5.8, 38, 6.0 ng/d, respectively). Air inhalation in offices was also an important exposure pathway for ΣPenta-, ΣOcta- and ΣDecaBDE in adults. For ΣPentaBDE and HBCD, air inhalation and dust ingestion play minor roles when compared to previously published Swedish dietary intakes (median exposures). However, in worst case scenarios using maximum concentrations, dust ingestion may represent 77 and 95% of toddler intake for ΣPentaBDE and HBCD, respectively.     

Short and medium chain length chlorinated paraffins in UK human milk fat

Chlorinated paraffins (also called polychlorinated n-alkanes -- PCAs) are a class of industrial chemicals comprising chlorinated straight chain hydrocarbons. They have a wide range of applications and are now found in a range of environmental compartments. We analysed a total of 25 human milk-fat samples, donated by 18 individuals from the urban London and more rural Lancaster areas in the UK, for short chain PCAs (C(10)-C(13) sPCAs) and medium chain PCAs (C(14)-C(17) mPCAs), using gas chromatography-ECNI high-resolution mass spectrometry. Our study confirms that trace quantities of PCAs can reach human milk-fat. sPCAs were detected in all but four samples, while mPCAs were detected in all samples. The median sPCA concentration was 180 ng/g fat (range of 49 to 820 ng/g fat -- detected values only) and the median mPCA concentration was 21 ng/g fat (range of 6.2 to 320 ng/g fat). No differences were noted in ranges of observed values for either sPCAs or mPCAs between samples from London and Lancaster. Most samples also exhibited similar patterns of sPCAs and mPCAs. One sample exhibited a different pattern for sPCAs and mPCAs, an observation that may be related to differences in exposure or biological factors for this individual.     

Analysis of human milk to assess exposure to PAHs,PCBs and organochlorine pesticides in the vicinity Mediterranean city Mersin,Turkey

Assessment of human exposure to environmental persistent organic pollutants such as organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs) based on the levels in human breast milk provides a reasonable tool not only to assess the contaminant burden in mothers but also to assess potential exposure of breast-fed neonates. There are limited data on levels of PCBs and OCPs in humans but no previous reports from Turkey on chemically determined levels PAHs in human milk. The aim of this study was to report the levels and accumulation profiles of OCPs, PCBs and PAHs in 47 breast milk samples obtained from a Mediterranean city, Mersin. High resolution analyses were performed by a gas chromatography coupled with mass spectrometer (GC–MS). Dichlorodiphenyldichloroethane (4.4′-DDE) was the dominant pollutant. Beta-hexachlorocyclohexane (ß-HCH), dichlorodiphenyltrichloroethane (4.4′-DDT), dieldrin, hexachlorobenzene, oxy-chlordane, cis-heptachlorepoxide were the other main OCPs detected. Mean levels of ΣPCB congeners and WHO_PCB-TEQ were 9.94 and 0.001 ng/g lipid, respectively. PCB 153 showed the highest concentration (3.37 ng/g lipid), followed by PCB 138 and 180. For the dioxin-like PCBs, PCB 118 was the dominant (0.97 ng/g lipid). Naphthalene, phenanthrene, pyrene and fluoranthene were the major PAHs among the 16 PAHs detected. The estimated daily intakes of DDTs, PCBs, HCHs and HCB were not exceeded the tolerable daily intake (TDI) proposed by the Health Canada Guideline. These results indicate that the neonates of Mersin city are exposed to persistent organic pollutants analyzed in this study. However, neonates born in Mersin province are less exposed than the ones born in other regions, considering OCP and PCB levels in breast milk.     

Sources and human exposure implications of concentrations of organophosphate flame retardants in dust from UK cars,classrooms, living rooms,and offices

Concentrations of a number of organophosphate flame retardants (PFRs) were measured in floor dust collected from UK living rooms (n = 32), cars (n = 21), school and child daycare centre classrooms (n = 28), and offices (n = 61). While concentrations were overall broadly within the range of those reported previously for North America, Japan, and other European countries, median concentrations of TCIPP in all UK microenvironments exceeded those reported elsewhere in the world. Moreover, concentrations of TCIPP and TDCIPP in 2 UK car dust samples were – at 370 μg g^− 1 and 740 μg g^− 1 respectively – amongst the highest reported globally in indoor dust to date. Consistent with this, concentrations of TDCIPP in dust from UK cars exceed significantly those detected in the other microenvironments studied. Concentrations of EHDPP were shown for the first time to be significantly higher in classroom dust than in samples from other microenvironments. When compared to concentrations of PBDEs determined previously in the classroom dust samples; concentrations of all target PFRs exceeded substantially those of those PBDEs that are the principal constituents of the Penta- and Octa-BDE formulations. Moreover, while mass-based concentrations of BDE-209 exceeded those of most of our target PFRs, they still fell below those of TCIPP and EHDPP. In line with a previous observation in Sweden that indoor air contamination with TNBP was significantly lower in newer buildings; concentrations of TNBP in classroom dust were significantly higher in older compared to more recently-constructed schools. Consistent with the reported extensive use of TCIPP and TDCIPP in polyurethane foam, the highest concentrations of both TCIPP and TDCIPP in the classrooms studied, were observed in rooms containing the highest numbers of foam chairs (n = 31 and 18 respectively). Exposure to PFRs of both adults and young children via ingestion of indoor dust was estimated. While even our high-end exposure estimate for young children was ~ 100 times lower than one previously reported health-based limit (HBLV) value for TCIPP; the margin of safety was only 5-fold when compared to another HBLV for this contaminant.     

Estimating human exposure to transport noise in central Dublin, Ireland

This paper reports on research conducted to determine estimates of the extent of environmental noise exposure from road transport on residents and workers in central Dublin, Ireland. The Harmonoise calculation method is used to calculate noise values for the study area while a Geographical Information System (GIS) is utilised as a platform upon which levels of noise exposure are estimated. Residential exposure is determined for L(den) and L(night) while worker exposure is determined for L(den). In order to analyse the potential of traffic management as a noise abatement measure, traffic was redirected from the main residential areas to alternative road links and the revised exposure levels were determined. The results show that the extent of noise exposure in Dublin is considerable, and in relative terms, it is worse for the night-time period. In addition, the results suggest also that traffic management measures have the potential to lead to significant reductions in the level of noise exposure provided that careful consideration is given to the impact of traffic flows on residential populations.     

Attitudes to coping with radiologically suspect or contaminated milk in the UK: a dairy industry viewpoint

The attitudes of the UK milk processing industry to a nuclear incident which resulted in milk supplies being suspected of being contaminated, or actually being contaminated, with radioactivity is examined. The factors influencing these attitudes are discussed, together with their implications. In the event of a nuclear incident in which part of the United Kingdom's milk supply is possibly contaminated, the milk processing industry will want to ensure that consumers and retailers maintain complete confidence in dairy products. As a consequence the industry will require that solutions are not adopted merely to avoid wastage of milk, or awkward milk disposal problems. In the early history of the BSE crisis the government wrongly assured consumers that beef was completely safe to eat. It will be necessary to ensure that any assurances that milk is safe, following a nuclear incident, are well founded.     

Fate, behavior and effects of surfactants and their degradation products in the environment

Surfactants are widely used in household and industrial products. After use, surfactants as well as their products are mainly discharged into sewage treatment plants and then dispersed into the environment through effluent discharge into surface waters and sludge disposal on lands. Surfactants have different behavior and fate in the environment. Nonionic and cationic surfactants had much higher sorption on soil and sediment than anionic surfactants such as LAS. Most surfactants can be degraded by microbes in the environment although some surfactants such as LAS and DTDMAC as well as alkylphenols may be persistent under anaerobic conditions. LAS were found to degrade in sludge amended soils with a half-lives of 7 to 33 days. Most surfactants are not acutely toxic to organisms at environmental concentrations and aquatic chronic toxicity of surfactants occurred at concentrations usually greater than 0.1 mg/L. However, alkylphenols have shown to be capable of inducing the production of vitellogenin in male fish at a concentration as low as 5 microg/L. More toxicity data are needed to assess the effects on terrestrial organisms such as plants.     

Concentrations of cyclic volatile methylsiloxanes in European cosmetics and personal care products: Prerequisite for human and environmental exposure assessment

Low molecular weight cyclic volatile methylsiloxanes (cVMSs) are widely employed as emollients and carrier solvents in personal care formulations in order to acquire desired performance benefits owing to their distinctive physicochemical properties. Under current European legislation cosmetic ingredients such as cVMSs are required to be labeled on the product package only qualitatively, while for the assessment of environmental and consumer exposure quantitative information is needed. The aim of this study was therefore to measure concentrations of three cVMSs, namely octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) in 51 cosmetics and personal care products (C&PCPs) that are currently available on the European market. The list of selected articles comprised a variety of hair and sun care products, skin creams and lotions, deodorants including antiperspirants, liquid foundations and a toothpaste. The target compounds were extracted from the products with different organic solvents dependent on the product matrix, followed by gas chromatography analysis with flame ionization detection (GC–FID). D5 was the predominant cVMS with the highest mean and median concentrations in all the C&PCP categories. The median concentrations of D5, D6 and D4 were 142, 2.3 and 0.053 mg/g in deodorants/antiperspirants (n = 11); 44.6, 30.0 mg/g and below the limit of quantification (< LOQ; LOQ for D4 = 0.00071 mg/g) in cosmetics (n = 5); 8.4, 0.32 mg/g and < LOQ in skin care (n = 16); 9.6, 0.18 and 0.0055 mg/g in hair care (n = 10); and, 34.8, 0.53 and 0.0085 mg/g in sun care (n = 8) products, respectively. The calculated median aggregate daily dermal exposure to D4 and D5 from multiple C&PCPs was approximately 100 times lower than the current NOAEL derived from chronic inhalation rat studies.     

Investigating the relationship between air pollution, health and social deprivation in Leeds, UK

This study examines the relationship between air pollution, social deprivation and health in the city of Leeds, UK under a baseline and three distance-based road user charging (RUC) scenarios set at 2 pence, 10 pence and 20 pence/km. Through application of a series of linked models of traffic, emission and pollutant dispersion, air quality was modelled in response to RUC scenarios. The pollutant modelled were NO(2), PM(10), CO, benzene and 1,3-butadiene, though results of NO(2) are used in this study. The RUC scenarios were compared with the 'base' scenario, all set for the year 2005. The RUC initiatives result in the differences in ambient concentrations of NO(2). The study correlates NO(2) concentrations with derived indices of social deprivation and health. The study concludes that positive but weak relationship exists between air quality and social deprivation, and indicates that deprived population groups are disproportionately exposed to higher NO(2) levels. The relationship between air quality and health status of the population is weak. There is a strong relationship between social deprivation and health status of the population. The study concludes that RUC scenarios result in reducing disparity between affluent and deprived populations.     

Aggregate dermal exposure to cyclic siloxanes in personal care products: Implications for risk assessment

Consumers who use personal care products (PCPs) are internally exposed to some of the organic components present of which some may be detected in exhaled air when eliminated. The aim of this study was the quantitative determination of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in end-exhaled air to study dermal absorption of substances in PCPs. We exposed the forearm of fifteen healthy volunteers for 60 min to pure D4 or D5 and to commercial products containing D4 and D5. Inhalation uptake was kept to a minimum by keeping the forearm in a flow cabinet during dermal exposure and supplying filtered air to the breathing zone of the volunteer during the post-exposure period. End-exhaled air was collected using a breath sampler (Bio-VOC), transferred to carbograph multi-bed adsorbent tubes and analyzed by thermal desorption gas chromatography mass spectrometry (TD-GC-MS). In the end-exhaled air of non-exposed volunteers background concentrations of D4 (0.8–3.5 ng/L) and D5 (0.8–4.0 ng/L) were observed. After exposing the volunteers, the level of D4 and D5 in end-exhaled air did not or barely exceed background concentrations. At t = 90 min, a sharp increase of the D4/D5 concentration in end-exhaled air was observed, which we attributed to the inhalation of the substances during a toilet visit without using inhalation protection devices. When this visit was taken out of the protocol, the sharp increase disappeared. Overall, the results of our study indicate that dermal absorption of D4 and D5 contributes only marginally to internal exposure following dermal applications. As in our study inhalation is the primary route of entry for these compounds, we conclude that its risk assessment should focus on this particular exposure route.     

Global genomic methylation levels in the liver and gonads of the three-spine stickleback (Gasterosteus aculeatus) after exposure to hexabromocyclododecane and 17-beta oestradiol

Alteration of DNA methylation is a major epigenetic mechanism associated with the effects of nongenotoxic carcinogens. We evaluated the effects of two environmental pollutants, hexabromocyclododecane (HBCD), 17-beta oestradiol (E(2)) as well as 5-aza 2' deoxycytidine (5AdC) on global DNA methylation levels (5-methyl 2' deoxycytidine) in the liver and gonads of the three-spine stickleback (Gasterosteus aculeatus). HBCD at 30 and 300 ng/L of water did not produce statistically significant differences in global genomic methylation in liver of female stickleback. On the other hand, the methylation inhibitor, 5-aza-2'-deoxycytidine, significantly lowered hepatic global methylation levels in these fish by 14% (P<0.05). The naturally occurring oestrogen, 17-beta oestradiol (E(2)) at 100 ng/L also decreased global DNA methylation levels in female liver but this effect was not statistically significant. In contrast, both E(2) and 5AdC caused statistically significant (P<0.001 and P<0.01 respectively) global genomic hypermethylation in the gonads of male sticklebacks although the increase seen in the female gonads was not statistically significant. The male gonad effect though unexplained may potentially be an indirect response to hypomethylation in other tissues (such as the liver) and may have important implications regarding oestrogenic effects in fish. The contrasting effects of HBCD and E(2) on global DNA methylation in stickleback should contribute to the integrated risk assessment of these environmental chemicals.     

Chlorinated paraffins in indoor air and dust: concentrations, congener patterns, and human exposure

Chlorinated paraffins (CPs) are large production volume chemicals used in a wide variety of commercial applications. They are ubiquitous in the environment and humans. Human exposure via the indoor environment has, however, been barely investigated. In the present study 44 indoor air and six dust samples from apartments in Stockholm, Sweden, were analyzed for CPs, and indoor air concentrations are reported for the first time. The sumCP concentration (short chain CPs (SCCPs) and medium chain CPs (MCCPs)) in air ranged from <5-210 ng m(-3) as quantified by gas chromatography coupled to electron ionization tandem mass spectrometry (GC/EI-MS/MS). Congener group patterns were studied using GC with electron capture negative ionization MS (GC/ECNI-MS). The air samples were dominated by the more volatile SCCPs compared to MCCPs. SumCPs were quantified by GC/EI-MS/MS in the dust samples at low μg g(-1) levels, with a chromatographic pattern suggesting the prevalence of longer chain CPs compared to air. The median exposure to sumCPs via the indoor environment was estimated to be ~1 μg day(-1) for both adults and toddlers. Adult exposure was dominated by inhalation, while dust ingestion was suggested to be more important for toddlers. Comparing these results to literature data on dietary intake indicates that human exposure to CPs from the indoor environment is not negligible.     

Use of pooled samples to assess human exposure to parabens,benzophenone-3 and triclosan in Queensland,Australia

Parabens, benzophenone-3 and triclosan are common ingredients used as preservatives, ultraviolet radiation filters and antimicrobial agents, respectively. Human exposure occurs through consumption of processed food and use of cosmetics and consumer products. The aim of this study was to provide a preliminary characterisation of exposure to selected personal care product chemicals in the general Australian population. De-identified urine specimens stratified by age and sex were obtained from a community-based pathology laboratory and pooled (n = 24 pools of 100). Concentrations of free and total (sum of free plus conjugated) species of methyl, ethyl, propyl and butyl paraben, benzophenone-3 and triclosan were quantified using isotope dilution tandem mass spectrometry; with geometric means 232, 33.5, 60.6, 4.32, 61.5 and 87.7 ng/mL, respectively. Age was inversely associated with paraben concentration, and females had concentrations approximately two times higher than males. Total paraben and benzophenone-3 concentrations are significantly higher than reported worldwide, and the average triclosan concentration was more than one order of magnitude higher than in many other populations. This study provides the first data on exposure of the general Australian population to a range of common personal care product chemical ingredients, which appears to be prevalent and warrants further investigation.     

Human exposure to PCDD/Fs in the UK: the development of a modelling approach to give historical and future perspectives

In order to assess the long-term impact of persistent organic contaminants such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) it is important to be able to quantify historical exposure. An understanding of past exposure is not only important to place our current body burdens in perspective, but is useful in assessing our potential future exposure. Unfortunately, very few direct measurements of our main source of exposure (i.e., food) over the past decades are available. This study attempts to reconstruct the historical exposure of the UK population to PCDD/Fs using a combination of emission estimates, information on environmental temporal trends derived from sediment cores and archived materials, and environmental/human fate modelling. Predicted adipose and blood lipid concentrations for a typical cross section of the population are derived over time (1920-2000), which is compared with measured data. The approach has been tested with two PCDDs and two PCDFs and showed encouraging agreement with measured data. Certain parts of the modelling methodology have been highlighted where there is still poor understanding of the processes governing fate and behaviour. These areas are discussed and recommendations for future improvements are made. The paper thus represents an initial modelling approach which defines both the historical (1920-present) and future (present-2020) fate of PCDD/Fs in the UK population.     

Perfluorooctane sulfonate: A review of human exposure,biomonitoring and the environmental forensics utility of its chirality and isomer distribution

Perfluorooctane sulfonate (PFOS) found extensive use for over 60 years up until its restriction in the early 2000s, culminating in its listing under the Stockholm Convention on Persistent Organic Pollutants (POPs) in 2009. Efforts to minimise human body burdens are hindered by uncertainty over their precise origins. While diet appears the principal source for the majority of western populations (with other pathways like dust ingestion, drinking water and inhalation also important contributors); the role played by exposure to PFOS-precursor compounds followed by in vivo metabolism to PFOS as the ultimate highly stable end-product is unclear. Such PFOS-precursor compounds include perfluorooctane sulfonamide derivates, e.g., perfluorooctane sulfonamides (FOSAs) and sulfonamidoethanols (FOSEs). Understanding the indirect contribution of such precursors to human body burdens of PFOS is important as a significant contribution from this pathway would render the margin of safety between the current exposure limits and estimates of external exposure to PFOS alone, narrower than hitherto appreciated. Estimates derived from mathematical modelling studies, put the contribution of so-called “precursor exposure” at between 10% and 40% of total PFOS body burdens. However, there are substantial uncertainties associated with such approaches. This paper reviews current understanding of human exposure to PFOS, with particular reference to recent research highlighting the potential of environmental forensics approaches based on the relative abundance and chiral signatures of branched chain PFOS isomers to provide definitive insights into the role played by “precursor exposure”.     

Occurrence of parabens in foodstuffs from China and its implications for human dietary exposure

Parabens are alkyl esters of p-hydroxybenzoic acid and are used as antimicrobial preservatives in a range of consumer products, including cosmetics, pharmaceuticals, and foodstuffs. Despite their widespread use, prior to this study, paraben concentrations in foodstuffs from China and human dietary exposure to these chemicals have been unknown. In this study, concentrations of six parabens were determined in 13 categories of food samples (n = 282), including cereals and cereal products, meat, fish and seafood, eggs, dairy products, bean products, fruits, vegetables, cookies, beverages, cooking oils, condiments, and others, collected from nine cities in China. Almost all (detection rate: 99%) food samples contained at least one of the parabens analyzed, and the total concentrations (ΣParabens; sum of six parabens) ranged from below limit of quantification (LOQ) to 2530 ng/g fresh weight, with an overall mean value of 39.3 ng/g. Methyl paraben (MeP), ethyl paraben (EtP), and propyl paraben (PrP) were the major paraben analogs found in foodstuffs, and these compounds accounted for 59%, 24%, and 10%, respectively, of ΣParaben concentrations. Although the mean concentrations of ΣParabens varied among different categories of food items (from 0.839 ng/g in beverages to 100 ng/g in vegetables), the concentrations were not statistically significant among the 13 food categories, including canned foodstuffs. Estimated daily intake (EDI) of parabens was based on the measured concentrations in foods and the corresponding daily food ingestion rates. The mean and 95th percentile values for EDI were 1010 and 3040 ng/kg body weight (bw)/day for adult men and 1060 and 3170 ng/kg bw/day for adult women, respectively.     

Doses of external exposure in Jordan house due to gamma-emitting natural radionuclides in building materials

The use of building materials containing naturally occurring radionuclides as ⁴⁰K, ²³²Th, and ²³⁸U and their progeny results in external exposures of the residents of such buildings. In the present study, indoor dose rates for a typical Jordan concrete room are calculated using Monte Carlo method. Uniform chemical composition of the walls, floor and ceiling as well as uniform mass concentrations of the radionuclides in walls, floor and ceiling are assumed.Using activity concentrations of natural radionuclides typical for the Jordan houses and assuming them to be in secular equilibrium with their progeny, the maximum annual effective doses are estimated to be 0.16, 0.12 and 0.22 mSv a⁻¹ for ⁴⁰K, ²³²Th- and ²³⁸U-series, respectively. In a total, the maximum annual effective indoor dose due to external γ-radiation is 0.50 mSv a⁻¹. Additionally, organ dose coefficients are calculated for all organs considered in ICRP Publication 74. Breast, skin and eye lenses have the maximum equivalent dose rate values due to indoor exposures caused by the natural radionuclides, while equivalent dose rates for uterus, colon (LLI) and small intestine are found to be the smallest. More specifically, organ dose rates (nSv a⁻¹ per Bq kg⁻¹) vary from 0.044 to 0.060 for ⁴⁰K, from 0.44 to 0.60 for radionuclides from ²³⁸U-series and from 0.60 to 0.81 for radionuclides from ²³²Th-series.The obtained organ and effective dose conversion coefficients can be conveniently used in practical dose assessment tasks for the rooms of similar geometry and varying activity concentrations and local-specific occupancy factors.     

Nonylphenol and octylphenol in human breast milk

Human milk is the most important form of nourishment for newborn children. Its consumption is strongly recommended by health authorities also for other important advantages. Unfortunately, in the last three decades a great number of investigations have shown the occurrence of several environmental contaminants in human milk, especially those with lipophilic properties. This study investigates the presence of nonylphenol, octylphenol (OP), nonylphenol monoethoxylate (NP1EO) and two octylphenol ethoxylates (OPEOs) (namely OP1EO and OP2EO), in human breast milk of Italian women. NP was the contaminant found at the highest levels with mean concentrations of 32 ng/mL, about two orders of magnitude higher than OP (0.08 ng/mL), OP1EO (0.07 ng/mL) and OP2EO (0.16 ng/mL). In the group of study a positive correlation among fish consumption and levels of NP in the milk was observed, in accordance with the evidence that seafood represents one of the most important sources of exposure to this group of contaminants in Italy. On the basis of the concentrations found in the breast milk samples, a maximum NP daily intake of 3.94 mug/kg/day can be calculated, which is close to the Tolerable Daily Intake (TDI) of 5 mug/kg body weight (bw) proposed by the Danish Institute of Safety and Toxicology. In the cases of OP no TDI is available, but its intake is at least six orders of magnitude lower than the NOAEL of 10 mg/kg/day derived from a two generation study on rats.