Biomedical subjects

G K Mortensen

Publications and source records attributed to G K Mortensen.

6 recordsLinked to original sources

PubMed2006

Possible impact of phthalates on infant reproductive health.

Phthalates adversely affect the male reproductive system in animals, inducing hypospadias, cryptorchidism, reduced testosterone production and decreased sperm counts. Phthalate effects are much more severe after in utero than adult exposure. Little is known about human health effects. This study discusses two recent studies on perinatal phthalate exposure, which indicated that human testicular development might be susceptible to phthalates. One study analysed phthalate monoesters in breast milk and reproductive hormone levels in infants. Five of six phthalates [monoethyl-(MEP), monobutyl- (MBP), monomethyl- (MMP), mono-2-ethylhexyl- (MEHP) and mono-isononyl phthalate (MiNP)] showed correlation with hormone levels in healthy boys, which were indicative of lower androgen activity and reduced Leydig cell function. MEP and MBP were positively correlated with serum sex hormone-binding globulin (SHBG) levels. MMP, MEP, MBP, MEHP and MiNP were positively correlated with the LH/testosterone ratio. Another study found a reduction of the anogenital index (AGI) in infant boys with increasing levels of MBP, MEP, monobenzyl- and mono-isobutyl phthalate in maternal urine samples during late-pregnancy. Boys with small AGI showed a high prevalence of cryptorchidism and small genital size. Taken together these studies suggest an antivirilizing effect of phthalates in infants. Most of these findings are in line with animal observations. However, the possible effects of MEP appear to be limited to humans. This may be due to differences in exposure routes (inhalation and dermal absorption which circumvents liver detoxification in addition to oral) and metabolism, or this association could be spurious. As phthalates are produced as bulk chemicals worldwide, these new findings raise concern about the safety of phthalate exposure for pregnant women and infants.

Environmental Pollutants↗

PubMed2002

Monitoring the content and intake of trace elements from food in Denmark.

The content of cadmium, lead, nickel, mercury and selenium in 83 foods was monitored from 1993 to 1997. In comparison with similar results from 1988 to 1992, a general decrease in lead levels had occurred, whereas the contents of cadmium, nickel, mercury and selenium were stable or declined only slightly. The distribution in dietary intake of the five trace elements was estimated by combining the mean trace element concentrations with food consumption data from 1837 Danes aged 15-80 years. The lead intake for 1993-97 showed a decrease in comparison with similar estimates from the previous monitoring cycles: 1983-87 and 1988-92. The intake of cadmium and mercury decreased to a lesser extent, whereas the intake of selenium and nickel remained unchanged in the same period. The dietary intake of trace elements was compared with the provisional tolerable weekly intake (PTWI). The 95th percentile of the distribution in cadmium intake amounts to 34% of PTWI, which is relatively high, and therefore calls for a more detailed future risk assessment. The intakes of lead and mercury were 11% of PTWI and, like the intake of nickel, did not cause any health concern in the adult population. The Danes ingest close to 100% of the Nordic Nutrition Recommendation for selenium at 50 microg day(-1), and no individuals had an intake less than the lower limit of 20 microg day(-1).

Adolescent↗

PubMed2001

Degradation of 4-nonylphenol in homogeneous and nonhomogeneous mixtures of soil and sewage sludge.

Sewage sludge is frequently applied as fertilizers to cultivated land. However, municipal sewage sludge often contains organic contaminants including nonylphenol (NP), an intermediate from nonionic surfactant degradation. Knowledge about NP degradation in sludge-amended soil is an important prerequisite for adequate risk assessments. In this study, mineralization of 14C-labeled NP in homogenized and nonhomogenized sludge-soil mixtures was investigated. NP was degraded within 38 days in aerobic homogenized mixtures. In nonhomogeneous mixtures containing sludge aggregates, the degradation of NP was retarded and was generally not completed within 3 months (119-126 days). No detectable amounts of NP were transported from the sludge aggregates to the surrounding soil (detection limit: <0.04 mg of NP/kg dw of soil). Oxygen penetration into sludge aggregates was monitored for 50 days with an oxygen microelectrode. An extrapolation of the oxygen data suggested that more than 1 year was required to obtain fully aerobic conditions in a 2-cm sludge aggregate. Since NP is considered persistent in the absence of oxygen, residual amounts of NP may be present in the anaerobic center of aggregates for prolonged periods. The results demonstrate that sludge aggregate size and thus oxygen availability will be a major controlling factor for NP degradation in soil amended with sewage sludge and that the mobility of NP from sludge aggregates to the surrounding soil is negligible.

Agriculture↗

PubMedDate not supplied

Beverages as a source of toxic trace element intake.

Beverages of different kinds have been investigated for their content of lead, cadmium, nickel, chromium, arsenic and mercury. About a ten times higher lead concentration was found in wine than in most other beverages. Cocoa was high in cadmium and nickel and some vegetable juices contained high levels of nickel. The daily intake of trace elements from beverages was estimated. Wine was still the most significant source of lead even if the bottles did not have lead capsules. By consumption of half a bottle per day the daily intake of lead would be doubled and it would contribute 12% of Provisional Tolerable Weekly Intake. Cocoa is an important source of cadmium and nickel, and consumption of tea as well as vegetable juices could increase the nickel intake significantly. The data are compared to Danish maximum limits on lead and cadmium.

Beverages↗

PubMedDate not supplied

Trace elements in shellfish on the Danish market.

Different kinds of shellfish have been investigated for their contents of the trace elements cadmium, lead, mercury, nickel, chromium, arsenic and selenium. The investigation included shrimps, mussels, lobster, langoustine, crayfish, crab claws and oyster. None of the Danish action levels for cadmium, lead and mercury respectively were exceeded, but the highest concentration of lead was very close to the Danish action levels. Shellfish do not contribute significantly to the intake of the trace elements investigated.

Denmark↗

PubMedDate not supplied

Influence of plant growth on degradation of linear alkylbenzene sulfonate in sludge-amended soil.

Widespread application of sewage sludge to agricultural soils in Denmark has led to concern about the possible accumulation and effects of linear alkylbenzene sulfonate (LAS) in the soil ecosystem. Therefore, we have studied the uptake and degradation of LAS in greenhouse pot experiments. Sewage sludge was incorporated into a sandy soil to give a range from very low to very high applications (0.4 to 90 Mg dry wt. ha(-1)). In addition, LAS was added as water solutions. The soil was transferred to pots and sown with barley (Hordeum vulgare L. cv. Apex), rape (Brassica napus L. cv. Hyola 401), or carrot (Daucus carota L.). Also, plant-free controls were established. For all additions there was no plant uptake above the detection limit at 0.5 mg LAS kg(-1) d.w, but plant growth stimulated the degradation. With a growth period of 30 d, LAS concentrations in soil from pots with rape had dropped from 27 to 1.4 mg kg(-1) dry wt., but in plant-free pots the concentration decreased only to 2.4 mg kg(-1) dry wt. When LAS was added as a spike, the final concentration in soil from planted pots was 0.7 mg kg(-1) dry wt., but in pots without plants the final concentration was much higher (2.5 mg kg(-1) dry wt.). During degradation, the relative fraction of homologues C10, C11, and C12 decreased, while C13 increased.

Agriculture↗