Environmental contaminants and human health in the Canadian Arctic.

The third Canadian Arctic Human Health Assessment conducted under the Canadian Northern Contaminants Program (NCP), in association with the circumpolar Arctic Monitoring and Assessment Programme (AMAP), addresses concerns about possible adverse health effects in individuals exposed to environmental contaminants through a diet containing country foods. The objectives here are to: 1) provide data on changes in human contaminant concentrations and exposure among Canadian Arctic peoples; 2) identify new contaminants of concern; 3) discuss possible health effects; 4) outline risk communication about contaminants in country food; and 5) identify knowledge gaps for future contaminant research and monitoring. The nutritional and cultural benefits of country foods are substantial; however, some dietary studies suggest declines in the amount of country foods being consumed. Significant declines were found for most contaminants in maternal blood over the last 10 years within all three Arctic regions studied. Inuit continue to have the highest levels of almost all persistent organic pollutants (POPs) and metals among the ethnic groups studied. A greater proportion of people in the East exceed Health Canada's guidelines for PCBs and mercury, although the proportion of mothers exceeding these guidelines has decreased since the previous assessment. Further monitoring and research are required to assess trends and health effects of emerging contaminants. Infant development studies have shown possible subtle effects of prenatal exposure to heavy metals and some POPs on immune system function and neurodevelopment. New data suggest important beneficial effects on brain development for Inuit infants from some country food nutrients. The most successful risk communication processes balance the risks and benefits of a diet of country food through input from a variety of regional experts and the community, to incorporate the many socio-cultural and economic factors to arrive at a risk management decision that will be the most beneficial in Arctic communities.

Assessment of microbiological quality of drinking water from household tanks in Bermuda.

Bermuda residents collect rainwater from rooftops to fulfil their freshwater needs. The objective of this study was to assess the microbiological quality of drinking water in household tanks throughout Bermuda. The tanks surveyed were selected randomly from the electoral register. Governmental officers visited the selected household (n = 102) to collect water samples and administer a short questionnaire about the tank characteristics, the residents' habits in terms of water use, and general information on the water collecting system and its maintenance. At the same time, water samples were collected for analysis and total coliforms and Escherichia coli were determined by 2 methods (membrane filtration and culture on chromogenic media, Colilert kit). Results from the 2 methods were highly correlated and showed that approximately 90% of the samples analysed were contaminated with total coliforms in concentrations exceeding 10 CFU/100 mL, and approximately 66% of samples showed contamination with E. coli. Tank cleaning in the year prior to sampling seems to protect against water contamination. If rainwater collection from roofs is the most efficient mean for providing freshwater to Bermudians, it must not be considered a source of high quality drinking water because of the high levels of microbial contamination.

Prevalence of asthma in a large group of Israeli adolescents: influence of country of birth and age at migration.

BACKGROUND: The occurrence of asthma has geographic variations and is lower in developing compared with industrialized countries. Both environmental and genetic factors may influence its prevalence. We aimed to evaluate the importance and effect of immigration (country of birth and age at immigration to Israel) on the prevalence of asthma in a large group of Israeli adolescents. METHODS: Computerized medical records of 17-year-old adolescents, who underwent routine examination before military recruitment, were studied. The sample comprised both native-born Israelis (NBI) and immigrants from Ethiopia, the Former Soviet Union (FSU), and Western countries (WC). Asthma was defined as clinical symptoms and signs compatible with the disease accompanied by abnormal spirometry or documented chronic use of inhaled steroids. RESULTS: Our cohort consisted of 1 466 654 adolescents, including 1 317 556 (89.8%) NBI and 149 098 (10.2%) immigrants. The prevalence of asthma at age 17 was higher in NBI compared with Ethiopian immigrants [4.7% (61 921) vs 2.6% (418), respectively, P < 0.0005], lower compared with immigrants from WC [5.6% (2177), P < 0.0005], and similar to immigrants from the FSU. Further analysis of the association between age at immigration and the risk for developing asthma showed that the younger immigrants from the FSU and Ethiopia arrived to Israel, the higher their prevalence of asthma at the age of 17 was. CONCLUSIONS: Both environmental and genetic factors seem to influence the prevalence of asthma in 17-year-old adolescents. However, the higher risk for developing asthma associated with young age of immigration points toward an environmental predominance.

Balancing the risks and the benefits of local fish consumption in Bermuda.

Fish consumption today is widely recognized as highly beneficial since it constitutes a good source of several essential nutrients, such as selenium and polyunsaturated fatty acids (n-3 PUFA). However, fish can also contain contaminants such as mercury, which make the consumer, especially pregnant women, confused about the risk-benefit balance associated with fish consumption. This is particularly true for tropical fish species for which little information is available. We have previously reported that some Bermudian neonates had elevated mercury in their umbilical blood compared with international guidelines. The objective of this study was to give precise and balanced information on the content of mercury, selenium and PUFA in the most consumed fish species in Bermuda. In 2003 and 2006, a total of 307 fish were collected from 43 fish species and 351 samples were analysed (305 flesh samples, 44 liver samples, one roe and one fat sample) by inductively coupled plasma-mass spectrometry (ICP-MS) (metals) and high-resolution gas chromatography (HRGC) (fatty acids). Results show that mercury varies among species from 0.03 to 3.3 microg g(-1) and that it is possible for at-risk groups such as pregnant women to make informed choices concerning fish consumption, e.g. maximizing fish species rich in nutrients and low in mercury.

Non-steroidal anti-inflammatory drugs for the prevention and treatment of cancer.

Non-steroidal anti-inflammatory drugs (NSAIDs), both cyclooxygenase-2 (COX-2) selective and nonselective inhibitors, are amongst the most popular medications worldwide. Whilst their anti-inflammatory effect is well known, recent studies have demonstrated an unexpected effect in both the prevention and treatment of several types of cancer. The anticancerous effect of NSAIDs is believed to be mainly due to the inhibition of COX-2, which is overexpressed in many types of cancer and may play a major role in tumourigenesis. In this review, we will describe the possible mechanisms for NSAIDs anticancer effect and summarize the major clinical studies in cancer prevention and treatment. We will also discuss the effect of the recent reports of adverse cardiovascular effects on anticancer research of the selective COX-2 inhibitors.

Distribution and macromolecular binding of benzo[a]pyrene and two polychlorinated biphenyl congeners in female mice.

PCBs are complete rodent carcinogens and their potent tumor promoting activity has been reported, but their tumor-initiating activity remains controversial. Macromolecular binding of PCB metabolites has been demonstrated in vitro, but this issue remains unclear in vivo. The purpose of this study was to determine the binding affinity of 4-chlorobiphenyl and 3,3',4,4'-tetrachlorobiphenyl to proteins and DNA in vivo. C57/BL6 female mice were treated intraperitoneally with hepatic enzyme inducers (phenobarbital and beta-naphthoflavone) and then with 14C-labelled polychlorinated biphenyls or benzo[a]pyrene. The short-term distribution of labeled compounds into liver, lungs and kidneys and into different sub-cellular fractions of these tissues was assessed and the DNA and proteins from the 700 x g pellet were further purified to assess covalent binding. All compounds were distributed in low amounts into the liver, kidneys and lungs, with the greatest accumulation in the liver, and the lowest in lungs. In all tissues, test compounds were mostly found in cytosols and organellar pellets (10,000 x g), and lower amounts were present in nuclear pellets (700 x g) and microsomes. In lungs and kidneys, only benzo[a]pyrene showed significant covalent binding to proteins. In the liver, protein binding indices were significant for all compounds (P<0.05), but no significant binding of the test compounds to DNA could be demonstrated with this approach. Our results suggest that at the 24 h time point, all compounds were activated to electrophilic intermediates prone to macromolecular binding. Hepatic proteins apparently act as a sink for PCB-derived electrophiles, thus preventing detectable levels of covalent binding to hepatic DNA or to proteins in less metabolically active tissues.

[Thrombolytic therapy or primary coronary angioplasty in acute myocardial infarction? Israel Thrombolytic Survey Group].

There has been continuous debate over the superiority of primary percutaneous, transluminal, coronary angioplasty (PTCA) over thrombolysis for acute myocardial infarction (AMI). It was questioned whether this advantage of primary PTCA reported in selected populations by experienced centers can be replicated in our clinical practice. We compared demographic and clinical variables, therapies and outcome in AMI treated with primary PTCA vs thrombolytic therapy. Clinical and demographic variables of 1,678 unselected AMI patients (admitted January/February and May/July 1996) were analyzed in 16 cardiac care units with on-site catheterization facilities and ability to perform PTCA. Of these 803 (48%) were treated by thrombolysis and 99 (6%) by primary PTCA. The prevalence of adverse prognostic variables, such as anterior wall MI, heart failure on admission or during hospital stay, pulmonary edema, and ventricular tachycardia or fibrillation, was higher in the PTCA group. The 7-day, 30-day and 1-year mortality rates were similar in the 2 groups: 4%, 7.2% and 12.8%, respectively, in the PTCA group and 5%, 7.2% and 11.1% in the thrombolysis group. There was a trend toward lower mortality in subgroups of high-risk patients: those with heart failure on admission (Killip class > 1), the elderly (> 65 years), and those with previous MI treated with PTCA. After adjusting for confounders, treatment with primary PTCA was not found to be associated with lower mortality. Only a small proportion of AMI patients in Israel were treated with primary PTCA in 1996. The frequency of adverse prognostic factors among them was higher but their short and long term outcomes were similar to those of high risk patients treated with thrombolysis.

Cytochrome P450 CYP1A1 enzyme activity and DNA adducts in placenta of women environmentally exposed to organochlorines.

Organochlorine compounds bioaccumulate in fishing and hunting products included in the daily diet of many coastal populations. Prenatal and perinatal exposure to large doses of PCBs and PCDFs was shown to be deleterious on fetal and neonatal development, but information is scarce regarding possible effects of chronic low-dose exposure. This study investigates biomarkers of early effects in newborns from women exposed to organochlorines through the consumption of species from marine food chains, in two remote coastal regions of the province of Quebec (Canada). A CYP1A1-dependent enzyme activity (EROD) and DNA adducts were measured in placenta samples obtained from 30 women living on the Lower-North-Shore of the St. Lawrence River and 22 Inuit women from Nunavik (Arctic Quebec). These biomarkers were also assessed in 30 women from a Quebec urban center (Sept-Iles) as a reference group. Prenatal organochlorine exposure was determined by measuring these compounds in umbilical cord plasma. The amount of bulky polycyclic aromatic hydrocarbon (PAH)-related DNA adducts was significantly greater in the Lower-North-Shore group than in the reference group. Placental EROD activity and the amount of less bulky (OC-related) DNA adducts were significantly higher in the Nunavik group than in the reference group. For both biomarkers, smoking was found to be an important confounding factor. Organochlorine exposure was significantly associated with EROD activity and DNA adduct levels when stratifying for smoking. This study confirms that CYP1A1 enzyme induction and DNA adducts in placental tissue constitute useful biomarkers of early effects induced by environmental exposure to organochlorines.