Spatial trends and associated biological responses of organochlorines and brominated flame retardants in hatchlings of north Atlantic kittiwakes (Rissa tridactyla)

Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), some organochlorinated pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecane (HBCD), were analyzed in yolk sacs of kittiwake (Rissa tridactyla) hatchlings from Kongsfjorden at Svalbard (Norwegian Arctic; 79 degrees N) and from Runde, an island on the coast of Norway (62 degrees N). Retinol (vitamin A), retinyl palmitate, and alpha-tocopherol (vitamin E) were measured in plasma and liver of the hatchlings to examine whether these vitamins were associated with the POPs. Higher levels of PCBs and OCPs were found in hatchlings from Kongsfjorden than in hatchlings from Runde. However, HBCD levels were significantly lower in hatchlings from Kongsfjorden compared to those in hatchlings from Runde. No differences between the two populations of kittiwake hatchlings were found regarding levels of PBDEs. In comparison with seabirds from other European waters and the Canadian Arctic, the kittiwakes seemed to have relatively high levels of PBDEs and HBCD. No effects on morphological variables or vitamin levels by the POPs were revealed, but multivariate regression indicated that liver tocopherol levels may be influenced by POPs.     

Yolk PCB and Plasma Retinol Concentrations in Shag (Phalacrocorax aristotelis) Hatchlings

To evaluate the possibilities of applying plasma retinol as a biomarker of response in seabirds exposed to chronic low levels of organochlorines, the relationship between yolk content of polychlorinated biphenyls (PCBs) and plasma retinol levels were studied in newly hatched shag chicks (Phalacrocorax aristotelis) from the coast of central Norway. The mean concentration of 29 PCB-congeners (ΣPCB) in the yolk sac was 1.22 μg/g ww (wet weight basis) (SD = 0.57, n = 10), or 17.99 ng/g lw (lipid weight basis) (SD = 6.26, n = 10). Expressed as TCDD-equivalents (ΣTEQ), the exposure in the yolk sac was 43.9 pg/g ww (SD = 19.5, n = 10), or 637.1 pg/g lw (SD = 240.8, n = 10), considerably lower than the levels that have been associated with clear-cut lethal and sublethal effects such as egg mortality, hatchability, or live deformity in Phalacrocoracidae species. There were significant negative correlations between ΣPCB ww and the variables egg volume, yolk mass, and hatchling mass. We suggest that these relationships are passive causes of a higher lipid concentration in small eggs, rather than the PCB affecting the variables. Analyses showed that there was a borderline significant positive correlation between ΣPCB lw in yolk and plasma retinol concentration. Although the results indicate that plasma retinol level alone is a poor indicator of PCB exposure in shag hatchlings, the result may be related to the low level of contaminant exposure and the low sample size of the study. Received: 19 March 1998/Accepted: 15 October 1998     

Persistent organic pollutants in blood plasma of satellite-tracked adult male loggerhead sea turtles (Caretta caretta)

Risks from persistent organic pollutants (POPs) remain largely a mystery for threatened loggerhead sea turtles (Caretta caretta). The present study examines regional-scale POP differences in blood plasma from adult male C. caretta based on movement patterns. Turtles were captured near Port Canaveral, Florida, USA, in April of 2006 and 2007 and fitted with satellite transmitters as part of a National Marine Fisheries Service-funded project. Residents (n = 9) remained near the capture site, whereas transients (n = 10) migrated northward, becoming established in areas largely from south of Pamlico Sound, North Carolina, to north of Cape May, New Jersey, USA. Blood was sampled from the dorsocervical sinus of each turtle and analyzed using gas chromatography-mass spectrometry for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and toxaphenes. Blood plasma concentrations of OCPs and total PBDEs were elevated in transients (p < 0.05) and in some cases were correlated with turtle size. Migratory adults showed an atypical PBDE congener profile relative to other published studies on wildlife, with PBDE 154 being the dominant congener. Additionally, PCB congener patterns differed between groups, with total PCBs slightly elevated in transients. This supports the idea that foraging location can influence exposure to, and patterns of, POPs in highly mobile species such as C. caretta. Understanding patterns of contamination informs wildlife managers about possible health risks to certain subpopulations. The present study is the first to examine POPs in the rarely studied adult male sea turtle and to couple contaminant measurements with satellite tracking.     

Polybrominated Diphenyl Ethers,Polychlorinated Biphenyls,and Organochlorine Pesticides in Adipose Tissues of Korean Women

Studies on residue levels and accumulation profiles of persistent organic pollutants (POPs) in human adipose tissues of Korean populations are scarce. In this study, concentrations and accumulation features of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) were measured in adipose tissues of Korean women age 40–68 years. The highest concentrations were found for PCBs and DDTs, which were 1–2 orders of magnitude greater than the concentrations of hexachlorocyclohexanes, chlordanes, and PBDEs. The concentrations of PCBs and OCPs were lower than those reported for other countries. However, PBDE concentrations were greater than those reported for other countries, suggesting that ongoing exposure to PBDEs is a concern in Korea. The profiles of PBDEs were characterized by the predominance of BDE 209, followed by nona- and octa-BDEs, which are consistent with the consumption patterns of products containing PBDEs in Korea. The concentrations of PCBs and some OCPs were significantly correlated with each other, whereas PBDEs showed low or moderate correlations with other POPs, suggesting differences in exposure routes and biotransformation potentials of the compounds studied. The concentrations of organochlorines and PBDEs were not correlated with subjects’ age and body mass index. The results of this study provide baseline information on POPs in adipose tissues of the general population in Korea.     

Persistent organochlorine and organobromine compounds in mother's milk from Sweden 1996-2006: Compound-specific temporal trends

High body burdens of persistent halogenated organic pollutants (POPs) among pregnant and nursing women are of concern because of exposure of the growing foetus and breast-feeding infant. We examined the temporal trends of polychlorinated biphenyls (PCBs), dibenzo-p-dioxin (PCDDs) and dibenzofurans (PCDFs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) in milk samples from Swedish women. POPs were analysed in individual mother's milk samples from randomly recruited primiparas (N=335) who lived in Uppsala County and delivered between 1996 and 2006. Results were adjusted for life-style factors that are associated with POP body burdens. PCB levels declined 3.9-8.6% per year. The levels of PCDDs decreased faster (6-9% per year) than the levels of PCDFs (3-6% per year). Temporal trends of PBDEs did not follow any consistent pattern. Concentrations of BDE-47 and BDE-99 decreased, while the concentrations of BDE-153 increased. No change in BDE-100 concentrations was observed. In most samples, concentrations of HBCD were below the quantification limit (<0.20 ng/g lipid). Generally, adjustment of the temporal trends of PCBs and PCDD/Fs for personal characteristics of the mothers (age, body mass index (BMI), weight changes during and after pregnancy) resulted in faster declining rates, with age having the greatest influence. The age of the participating mothers increased during the study period, and since the POP levels increased with increasing age, this counteracted the decreasing temporal trends in the unadjusted model. It is consequently important to include personal characteristics in the analysis of temporal trends of POPs. Compound-specific temporal trends are probably caused by differences in sources of exposure, as well as by differences in persistence between compounds.     

Changes in hepatic parenchymal and nonparenchymal cell vitamin A content during vitamin A depletion in the rat

Levels of total, unesterified and esterified retinol were determined in liver, liver parenchymal cells (PC) and liver nonparenchymal cells (NPC) during vitamin A depletion in rats. Liver vitamin A levels decreased from 113 to 4 micrograms over a 97-d experimental period; plasma retinol concentrations did not change significantly during this time. Initially, greater than 90% of hepatic vitamin A was in the esterified form and most (93%) was localized in NPC. During vitamin A depletion, there were significant declines in retinyl ester content of both PC and NPC, but unesterified retinol levels were not significantly affected. Plasma retinol concentrations were significantly correlated with unesterified retinol mass in PC and NPC, but not with retinyl ester mass. Although 94% of the liver's negative vitamin A balance was due to changes in NPC retinyl ester levels, the fractional rate of retinyl ester loss from PC and NPC was almost identical. Since unesterified retinol levels in plasma, PC and NPC appeared to be conserved even when liver retinyl ester stores were virtually depleted, and since the retinol utilization rate was apparently not decreasing during this stage of vitamin A depletion, these data support the hypotheses that homeostatic mechanisms controlling the three pools of unesterified retinol are linked, and that vitamin A utilization rate is maintained as long as unesterified retinol levels in plasma, PC and NPC are normal.     

Vitamin A intake and status influence retinol balance, utilization and dynamics in rats

To study effects of vitamin A status on retinol dynamics, male rats were fed purified diets varying in vitamin A concentration. Group 1 rats had marginal liver vitamin A levels (approximately 500 nmol) and were in a slight positive vitamin A balance; Group 2 had similar liver levels but were in a slight negative balance; Group 3 had lower liver levels (approximately 370 nmol) and were in a slight negative balance; Group 4 had depleted liver reserves (<10 nmol) and were in vitamin A balance. [3H]Retinol-labeled plasma was injected intravenously, and serial plasma samples were collected for 41 d while rats (six per group) consumed approximately 50 nmol retinol/d (Group 1) or -25 nmol/d (Groups 2-4). Plasma retinol was normal in Groups 1-3 (1.9-2.0 micromol/L) and lower in Group 4 (0.96 micromol/L). Plasma tracer data were fit to a three-compartment model. The central plasma retinol compartment (transit time, 1.5-1.7 h) exchanged with a fast turning-over extravascular vitamin A pool (transit time, 3-4.5 h; -40 nmol) and with a larger, slow turning-over extravascular pool (transit time, 5.5-10 d) that was the site of irreversible utilization of vitamin A. Irreversible utilization was 36 nmol/d (Group 1), 29 nmol/d (Groups 2 and 3) and 20 nmol/d (Group 4). The data indicate that in rats with low or marginal vitamin A status, vitamin A intake, vitamin A reserves and plasma retinol concentration all influence vitamin A utilization and other aspects of retinol dynamics.     

Response of plasma levels of vitamin A to a dose of vitamin A as an indicator of hepatic vitamin A reserves in rats.

Rats were fed diets deficient [-A] or sufficient [+A] (3 mg retinol equivalents/kg) in vitamin A, and without [-RA] or with [+RA] (12 mg/kg) retinoic acid supplementation for up to 33 days. Rats with plasma vitamin A levels ranging from 7 to 62 micrograms/dl were studied at intervals during progressive depletion of liver stores of vitamin A (expt. 2) and when liver stores were nearly exhausted (less than 10 micrograms/g) or replete (up to 100 micrograms/g) with vitamin A (expt. 1). A dose of retinyl acetate in corn oil (20 micrograms retinol equivalents) was administered by intubation directly into the stomach. The relative dose response (RDR), expressed as a percentage and defined as the absolute magnitude of the rise in plasma vitamin A levels 5 hours after the dose of retinyl acetate, divided by the plasma level of vitamin A attained after 5 hours, was determined for each rat and correlated over a wide range of vitamin A plasma and liver levels. An RDR above 50% invariably was associated with low plasma levels (10 to 30 micrograms/dl) and low liver stores (less than 10 micrograms/g) of vitamin A, whereas an RDR of less than 40% was associated with plasma levels above 30 micrograms/dl and liver stores ranging from 3 to 100 micrograms/g.     

Effects of retinoic acid on the metabolism of vitamin a in rat liver

Sprague-Dawley male rats with adequate storage of vitamin A were fed vitamin A deficient diet either alone (RA-) or supplemented with retinoic acid (RA+). The rats were sacrificed at different days for the measurement of free retinol and the composition of retinyl esters in liver. At the same time the plasma retinol levels of these rats were also determined. Supplementation of retinoic acid significantly lowered the plasma retinol levels with a concomitant slower depletion of the total vitamin A in the liver of RA+ rats as compared. to RA-rats. The ratio of retinyl esters to free retinol in the liver tissue of RA- rats decreased with time, whereas in RA+ rat livers the ratio remained constant. The percentage distribution of retinyl esters in the liver tissue revealed a significant decrease in saturated retinyl esters with an increase in unsaturated retinyl esters in the RA+ group compared to RA- group. These data support the earlier findings that retinoic acid spares the utilization of retinol and suggest that it may affect the release of retinol from retinyl esters in the liver.     

Long-term exposure of European flounder (Platichthys flesus) to the flame-retardants tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD)

Tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD) are widely used flame retardants that have increasingly been found as contaminants in the aquatic environment. In the present study, European flounder (Platichthys flesus) were chronically exposed to TBBPA; (105 days) and HBCD (78 days), in a wide range including environmentally relevant concentrations. TBBPA was administered via the water, whereas HBCD was administered in food and sediment, or in sediment alone. Chemical analysis of muscle showed an average increase in internal concentrations of approximately two orders of magnitude for both compounds tested. Animals exposed to HBCD via sediment alone (8000 microg/g total organic carbon, TOC) showed a proportional increase of alpha-HBCD in muscle compared to animals exposed via food and sediment. In both studies, exposure to the test compounds did not affect general health and toxicity parameters (behavior, survival, growth rate, relative liver and gonad weight). Hepatic microsomal enzyme activities (TBBPA: EROD; HBCD: EROD, PROD, and BROD) were not induced by any of the tested chemicals. Aromatase activity in male gonads showed a mild increase with rising TBBPA levels. There were no morphological and immunohistochemical indications for increased production of the yolk precursor protein vitellogenin (VTG) in animals exposed to TBBPA and HBCD; immunochemical analysis of plasma VTG levels showed no dose response in animals exposed to TBBPA. In animals exposed to TBBPA, levels of the thyroid hormone thyroxin (T(4)) increased with internal concentrations of the test compound, possibly indicating competition of TBBPA for plasma protein binding. Triiodothyronin (T(3)) levels were not affected and histology showed no signs of altered thyroid gland activity. Other organs investigated (liver, gills, kidney, skin, and gonads) revealed no histological changes related to TBBPA or HBCD exposure. Overall, the present results indicate limited endocrine effects of these widely used flame retardants in a test species representative of European estuaries at environmentally relevant exposure levels and at internal levels up to 4300 ng TBBPA/g wet weight, and 446 microg HBCD/g lipid weight in flounder muscle.     

A retrospective study of PBDEs and PCBs in human milk from the Faroe Islands

Background  

Persistent organic pollutants (POPs) in wildlife and humans remain a cause of global concern, both in regard to traditional POPs, such as the polychlorinated biphenyls (PCBs), and emerging POPs, such as the polybrominated diphenyl ethers (PBDEs). To determine the time related concentrations, we analyzed human milk for these substances at three time points between 1987 and 1999. Polychlorobiphenylols (OH-PCBs), the dominating class of PCB metabolites, some of which are known to be strongly retained in human blood, were also included in the assessment.     

Association between plasma and liver vitamin A levels in the calf; weanling pig, rabbit and rat; and adult goat fed fixed intakes of vitamin A.

To reexamine the relationship between plasma and liver vitamin A levels, data from various species of animals fed fixed intakes of vitamin A ester (expressed as retinol equivalents/kg liver weight/day) were vitamin A ester (expressed as retinol equivalents/kg live weight/day) were studied. The intakes ranging from deficient to toxic were for 48 calves, 4 to 17,600 micrograms; 39 pigs, 17.6 to 19,842 micrograms; 86 rabbits, 4.5 to 287 micrograms; 138 rats, 4 to 16,384 micrograms; and 40 goats, 1 to 17,640 micrograms. Following the feeding of these intakes for periods of between 5 and 133 weeks, blood and liver samples were taken for vitamin A determinations. Plasma vitamin A concentrations reached minimum values at low liver vitamin A levels whereas liver vitamin A levels reached maximum values at high plasma vitamin A concentrations. Upon elimination of data pairs at the extremes, linear regressions of log10 (total liver vitamin A) on plasma vitamin A concentrations and of plasma vitamin A concentrations on log10 (total liver vitamin A) were statistically significant. Therefore it was possible to estimate within limits the log10 (total liver vitamin A) from plasma vitamin A. Applicable limits were for the calf 8 to 46 micrograms/100 ml of plasma, for the pig 14 to 32, for the rabbit 14 to 74, for the rat 5 to 51 and for the goat 22 to 55. Simple correlation coefficients were 0.92, 0.60, 0.93, 0.92 and 0.75.     

Persistent Organochlorine Contaminant Residues in Tissues of Hedgehogs from Turkey

The residues of persistent organochlorinated pollutants (POPs), namely polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) (HCHs, CHLs, HCCPs, DDTs, and dicofol congeners) were investigated in the hair and muscle of road-killed Erinaceus roumanicus and E. concolor in Turkey. Mean residue levels were as follows: in hair, PCBs?=?7.43?±?4.88 ng/g and OCPs?=?9.21?±?1.27 ng/g; in muscle, PCBs?=?30.73?±?2.51 ng/g and OCPs?=?145.04?±?16.59 ng/g. There was no significant difference between species and sex, while there was significant difference between habitats and regions in terms of either total PCB and OCP levels, or POP levels (p?<?0.05). Age was a determinative factor for the bio-accumulation of POPs. The contaminant levels were high in the species, sample areas, and habitats. The data also showed that tissues of hedgehogs are suitable for monitoring and evaluating the bioaccumulation of POP levels in Turkey.     

Vitamins A, E, and carotene: effects of supplementation on their plasma levels

We conducted a randomized, double-blind trial among 59 generally well-nourished adults to determine the effects of vitamin A, vitamin E, and beta-carotene supplements on plasma retinol, alpha-tocopherol, and carotenoid levels. Over a period of 16 wk a daily alpha-tocopherol supplement of 800 IU approximately doubled plasma alpha-tocopherol levels (p less than 0.001), caused a small decrease in plasma carotenoids (p = 0.02), and produced a slight and statistically insignificant reduction in plasma retinol. A daily beta-carotene supplement of 30 mg (5000 retinol equivalents) approximately tripled plasma carotenoid levels (p less than 0.001) but did not affect plasma retinol or alpha-tocopherol. A daily retinyl palmitate supplement of 25,000 IU (13,750 retinol equivalents) did not appreciably affect plasma retinol, alpha-tocopherol, or carotenoid.     

Persistent organic pollutants in coastal sediment off South China in relation to the importance of anthropogenic inputs

Surface sediments collected from the coastal region off South China were analyzed for persistent organic pollutants (POPs), including polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs). The concentrations of BDE-209, Σ(12)PBDE, Σ(15)PAH, Σ(7)PAH, and Σ(11)OCP were 0.22 to 26.3, 0.01 to 0.77, 13.9 to 271, 6 to 133, and 0.9 to 104 ng/g, respectively. The spatial distribution patterns of PBDEs and PAHs suggested that the eastern coastal region was slightly more contaminated than the western coast. In addition, the concentrations of dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDXs) were highly variable, with the highest level found at a site in Zhanjiang Bay, which might have been reflective of the impact of antifouling paints mainly used in boat maintenance in harbor areas. The predominance of BDE-209 in the study region was consistent with the usage pattern of penta-, octa-, and deca-BDEs in China, whereas sediment PAHs appeared to have been derived largely from coal or wood and petroleum combustion. Preliminary assessments indicated that terrestrial inputs, such as atmospheric transport and riverine runoff, may have been the major input pathways for PBDEs and PAHs, respectively, to accumulate in coastal sediment off South China. Conversely, residues of DDT-containing antifouling paints associated with shipping activities and boat maintenance accounted for most of the accumulated sediment DDTs.     

Plasma Vitamin A Homeostasis: The Relative Dose Response As A Measure Of Liver Vitamin A Reserves

Retinol levels in plasma of rats are constant and independent of dietary intake or liver stores above 10 μg per gram. If tissue needs of retinol are decreased by limiting protein intake or by feeding retinoic acid, plasma levels correspondingly decline. A single dose of newly supplied vitamin A leads to a short-term surge in plasma retinol level which may be a measure of liver reserves and vitamin A status.     

Fish as biomonitors of polybrominated diphenyl ethers and hexabromocyclododecane in Czech aquatic ecosystems: pollution of the Elbe River basin

BACKGROUND: Brominated flame retardants (BFRs)--polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD)--belong to the group of relatively "new" environmental contaminants. The occurrence of these compounds in the Czech aquatic ecosystem was for the first time documented within the 3-year monitoring study initiated in 2001. In 2002-2003 HBCD and the major PBDE congeners (28, 47, 49, 66, 85, 99, 100, 153, 154, and 183) were found in 136 freshwater fish samples collected from several sampling sites located at three Czech rivers (Vltava, Elbe, Tichá Orlice). Chub (Leuciscus cephalus), barbel (Barbus barbus), bream (Abramis brama), perch (Perca fluviatilis), and trout (Salmo trutta), representing the most common fish species, were examined by gas chromatography coupled with negative chemical ionization mass spectrometry. RESULTS: The presence of PBDE congeners and HBCD was detected in all analyzed samples (limits of detection for target analyts ranged from 0.015 to 0.1 ng/g lipid weight). Without exception the dominating congener was BDE-47. The most pronounced extent of fish contamination was found in the Vltava river at Klecany, downstream from the industrial agglomeration of Prague. As for fish species, the highest concentrations of PBDEs (sum of congeners) were measured in benthic species, represented by bream and barbel, up to 19.6 ng/g wet weight and 16.5 ng/g wet weight, respectively. The lowest accumulation occurred in predator fish (perch and trout). The highest levels of HBCD were detected in barbel from Srnojedy on the Elbe River (15.6 ng/g wet weight), downstream.     

Lung retinyl ester is low in young adult rats fed a vitamin A deficient diet after weaning, despite neonatal vitamin A supplementation and maintenance of normal plasma retinol

Although it is understood that plasma retinol concentration is not proportional to the concentration of vitamin A stored in liver, plasma retinol still is often used as an indicator of vitamin A status. An aim of vitamin A supplementation strategies is to maintain plasma retinol concentration in a range considered adequate, generally >1.05 micromol/L in humans, with some adjustment for age. In the present study in rats, we addressed the following question: Does lung vitamin A increase postnatally, as is observed in rats fed a vitamin A-adequate diet, if plasma retinol is maintained at approximately 1 micromol/L by supplementation at neonatal age, but the weaning diet is deficient in vitamin A? We treated rats on postnatal d 6, 7, and 8 with placebo (oil), vitamin A, retinoic acid (RA), and a nutrient-metabolite combination of vitamin A and RA, VARA, after which tissues were analyzed on d 9. Other rats treated identically as neonates were fed a vitamin A-deficient diet from 3-9 wk of age, and in parallel, another group of rats was fed a vitamin A-adequate diet. Although supplementation with vitamin A or VARA elevated liver and lung retinyl esters (RE) on d 9 (P < 0.0001), and prevented the fall in plasma retinol to <1 micromol/L by 9 wk of age, when the diet was vitamin A-deficient, lung RE fell to 28% of the concentration present in the lungs of rats fed the vitamin A-adequate diet (P < 0.0001). We infer that the lungs depend, at least in part, on the uptake of dietary vitamin A, probably from chylomicrons, to develop RE stores in the postweaning growth period.     

Vitamin A and β-carotene supply of women with gemini or short birth intervals

Background An adequate supply of vitamin A during pregnancy and breastfeeding plays an important role for development of foetus and neonate, especially in lung development and function. Aim of the study Aim of this pilot study was to analyze vitamin A and β-carotene status and to investigate the contribution of nutrition to the vitamin A and β-carotene supply in mother–infant pairs of gemini or births within short birth intervals. Methods Twenty-nine volunteers aged between 21 and 36 years were evaluated for 48 h after delivery. During this time frame a food frequency protocol considering 3 months retrospective was obtained from all participants. In order to establish overall supply retinol and β-carotene levels were determined in maternal plasma, cord blood and colostrum via HPLC analysis. Results Regardless of the high to moderate socio-economic background, 27.6% of participants showed plasma retinol levels below 1.4 μmol/l which can be taken as borderline deficiency. In addition, 46.4% showed retinol intake <66% of RDA and 50.0% did not consume liver at all although liver contributes as a main source for preformed retinol. Despite high total carotenoid intake of 6.9 ± 3.6 mg/d, 20.7% of mothers showed plasma levels <0.5 μmol/l β-carotene. Retinol and β-carotene levels were highly significantly correlated between maternal plasma versus cord blood and colostrum. In addition, significantly lower levels were found in cord blood (31.2 ± 13.0% (retinol), 4.1 ± 1.4% (β-carotene) compared with maternal plasma. Conclusions Despite the fact that vitamin A and β-carotene rich food is generally available, risk groups for low vitamin A supply exist in the western world.     

Secretion of vitamin A and retinol-binding protein into plasma is depressed in rats by N-(4-hydroxyphenyl)retinamide (fenretinide).

In clinical trials the cancer preventive drug N-(4-hydroxyphenyl)retinamide (HPR) markedly lowers plasma concentrations of retinol and retinol-binding protein (RBP). Five hours after injection of HPR (51 mumol/kg), serum concentrations of retinol and RBP were 33 and 42% lower, respectively, than control values in rats. Because the mean transit time for retinol disappearance from serum of HPR-treated rats (1.9 h) was similar to that for radiolabeled retinol in control rats in previous studies, plasma retinol turnover is apparently not accelerated by HPR treatment. To study the effects of HPR on the secretion of the retinol-RBP complex from liver, control or HPR-treated rats were injected with chylomicrons containing [3H]vitamin A and [14C]triglycerides. Both labels were rapidly cleared from plasma in the two groups. In control rats [3H]retinol concentrations began to increase in plasma after 30 min due to liver secretion of retinol bound to RBP. In HPR-treated rats, secretion was apparently inhibited because the amount of [3H]retinol bound to RBP at 4.66 h was only 2.6% of the control level. We conclude that HPR partially blocks the secretion of the retinol-RBP complex from liver and other tissues, and thus depresses plasma concentrations of vitamin A and RBP.