Organochlorine exposure and colorectal cancer risk

Organochlorine compounds have been linked to increased risk of several cancers. Despite reductions in their use and fugitive release, they remain one of the most important groups of persistent pollutants to which humans are exposed, primarily through dietary intake. We designed a case-control study to assess the risk of colorectal cancer with exposure to these chemicals, and their potential interactions with genetic alterations in the tumors. A subsample of cases (n = 132) and hospital controls (n = 76) was selected from a larger case-control study in Barcelona, Catalonia, Spain. We measured concentrations in serum of several organochlorines by gas chromatography. We assessed point mutations in K-ras and p53 genes in tissue samples by polymerase chain reaction/single-strand conformation polymorphism and assessed expression of p53 protein by immunohistochemical methods. An elevated risk of colorectal cancer was associated with higher serum concentrations of mono-ortho polychlorinated biphenyl (PCB) congeners 28 and 118. The odds ratio for these mono-ortho PCBs for middle and higher tertile were, respectively, 1.82 [95% confidence interval (CI), 0.90-3.70] and 2.94 (95% CI, 1.39-6.20). alpha-Hexachlorocyclohexane, hexachlorobenzene, and pp'-DDE (4,4'-dichlorodiphenyltrichloroethene) showed nonsignificant increases in risk. Risk associated with mono-ortho PCBs was slightly higher for tumors with mutations in the p53 gene but was not modified by mutations in K-ras. Mono-ortho PCBs were further associated with transversion-type mutations in both genes. These results generate the hypothesis that exposure to mono-ortho PCBs contributes to human colorectal cancer development. The trend and magnitude of the association, as well as the observation of a molecular fingerprint in tumors, raise the possibility that this finding may be causal

PAHs associated with the leaves of three deciduous tree species. I - concentrations and profiles.

Results for the concentrations of total polycyclic aromatic hydrocarbons (ΣPAH) and the PAH profile in leaves from three deciduous tree species from the same woodland are presented, and discussed with reference to environmental and leaf-related variables. There were significant differences between oak, ash and hazel leaves in their ΣPAH concentrations (sum of 23 PAHs), and in the relative contribution of individual PAHs to the sum. Leaves exhibiting pubescence (hairiness) were found to have significantly higher ΣPAH concentrations than hairless leaves, regardless of their position in the vegetation strata of the wood. Hazel leaves from the understorey had a PAH profile consisting of a greater proportion of the 4-, 5- and 6-ring PAHs than oak or ash from the canopy. This was concluded to be the result of the filtering effect of the main canopy on the air passing over and through it, with subsequent transfer of particles and attendant PAHs to the understorey below. The proportion of ΣPAH contributed by the 6-ring PAH in hazel leaves was negatively correlated with distance from the southern edge of the canopy. It is proposed that the predominantly windward edges of the woodland, where atmospheric turbulence is likely to be greatest, favoured the deposition of particle-bound PAHs to leaves

PAHs associated with the leaves of three deciduous tree species. II : uptake during a growing season.

Leaves from three species of deciduous tree (oak, ash and hazel) were sampled at intervals through a growing season in a mature, mixed-deciduous woodland. Polycyclic aromatic hydrocarbon (PAH) concentrations remained within a small range for all species between May and September, deviating significantly only when increases in atmospheric concentrations of PAHs (notably from the ‘Bonfire night’ festival in early autumn) have been shown. We concluded that the influence of air concentrations was more important than meteorological conditions (temperature, humidity and rainfall) in determining plant concentrations of PAHs over a growing season. Concentrations of 4-, 5- and 6-ring PAHs were positively correlated with time for all species, but there were significant differences in the PAH profile between species sampled from the canopy (oak and ash) compared with the understorey (hazel). Oak and ash had similar PAH profiles, while hazel leaves had proportionally greater concentrations of the heavier molecular weight (4-, 5- and 6-ring) PAHs, and the ratios of these compounds to 3-ring PAHs was positively correlated with time. This affirms earlier work conducted on the same species in the same woodland, where we concluded that the canopy was filtering particles and attendant PAHs from air passing over or through it, and that these particles were transferred to the understorey and the woodland floor

PAHs in the soils of a mature, mixed-deciduous (Quercus-Fraxinus) woodland and the surrounding pasture.

A survey of PAHs in the soils of a mature,mixed-deciduous woodland and the surrounding pasturewas conducted along two transects. PAH `profiles'were not significantly different in the woodland soilcompared with the pasture. PAH concentrations in thewoodland soil were significantly higher than soil fromthe surrounding pasture by a factor of 1.5–3 (P < 0.01), indicating enhanced deposition of PAHs to thesoil under the canopy via leaf litter, stemflow and/or through-fall. A deposition `edge effect' was onlyobserved at the windward edge of the canopy where thenumber and density of aerial and basal stems washighest (P < 0.05). The influence of predominantwest/south-westerly winds was observable in the lackof an edge effect at the leeward edges, and the higherPAH concentrations in the predominantly leewardpasture compared to the windward pasture (P < 0.05)

Further developments in the use of semi-permeable membrane devices as passive air samplers : issues concerning their use for PCBs.

There are several incentives for developing passive air sampling techniques for persistent organic pollutants (POPs). This paper reports on studies to further calibrate and optimize semipermeable membrane devices (SPMDs) for use as “integrated” air samplers of gas-phase POPs. These samplers are deployed over weeks/months/years. Polychlorinated biphenyls (PCBs) were used as the test compounds in this study, with three specific objectives: (i) to determine whether ambient wind speed limits the rate of uptake during typical deployment conditions; (ii) to monitor uptake and SPMD−air equilibrium for a range of compounds; and (iii) to assess the application of performance reference compounds (PRCs) in air sampling, to “correct” for site-specific differences in uptake rates. When deployed in Stevensons screens under ambient conditions, wind speed did not significantly affect uptake rates. Rather, differences in summer/winter uptake rates reported previously, using the same deployment devices as here, are due to temperature affecting compound permeability through the membrane. Results from the use of PRCs indicate that SPMDs should be spiked prior to exposure with a range of compounds that are not present in the atmosphere, so that uptake rates can be estimated from depuration rates during a particular deployment. Short-term deployments (e.g. days; few weeks) would need to use compound(s) with a low octanol:air partition coefficient (KOA) (e.g. 13C12 labeled PCB-28); long-term deployments (of many months to years) would need to use intermediate KOA compounds (e.g. 13C12 PCB-101; 13C12 PCB-153)

Seasonal patterns of cadmium accumulation in Arrhenatherum elatius (Poaceae): Influence of mycorrhizal and endophytic fungal colonisation

International audienceWe investigated the influence of arbuscular mycorrhizae (AM) and dark septate fungi (DSF) colonisation on cadmium (Cd) accumulation in Arrhenatherum elatius from heavy metal-contaminated sites. AM colonisation disappeared when Cd concentrations in soil increased, while DSF infection was weak but constant throughout the experiment indicating that soil heavy metals are toxic to AM but not to DSF. AM colonisation was greatest when plant Cd concentrations were highest providing evidence that AM colonisation may influence Cd accumulation. In addition, the disappearance of AM and the concomitant reduction of Cd in shoots during seed maturation result in our suggestion that seasonal variation in AM may play a role in protecting developing seeds from soil pollution

Blood and urinary levels of metals and metalloids in the general adult population of Northern France: The IMEPOGE study, 2008–2010

International audienc

Further developments in the use of semipermeable membrane devices (SPMDs) as passive air samplers for persistent organic pollutants: field application in a spatial survey of PCDD/Fs and PAHs.

Semipermeable membrane devices (SPMDs) were deployed at 19 sites in northwest England to test their efficacy as passive atmospheric samplers for polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs). SPMDs were found to be efficient samplers for vapor phase species in the atmosphere, with good reproducibility between samplers. Species which are partially or completely particle associated under ambient U.K. conditions were also sampled by the SPMDs but with poorer reproducibility. It is suggested that SPMDs could be used to indicate “hot-spots” of particulate associated species, however. Differences in absolute and relative concentrations of all PCDD/Fs and PAHs sequestered by the SPMDs were observed between sites. High amounts were sequestered in SPMDs at sites where previous active monitoring has indicated relatively high atmospheric concentrations, confirming the potential of SPMDs as a tool for semiquantitative spatial monitoring of atmospheric species. SPMDs also respond to differences in the mixture of compounds present in the atmosphere, thereby aiding source apportionment studies

1-Hydroxypyrene and 3-hydroxybenzo[a]pyrene as biomarkers of exposure to PAH in various environmental exposure situations

International audienc