Antti Huusko

Some comments on spatial variation in arboreal pollen deposition: first records from the Pollen Monitoring Programme (PMP)

Some comments on spatial variations in arboreal pollen deposition: first records from the Pollen Monitoring Programme (PMP).

Standardised regression coefficient as an effect size index in summarising findings in epidemiological studies

Background: a major problem in evaluating and reviewing the published findings of studies on the association between a quantitative explanatory variable and a quantitative dependent variable is that the results are analysed and reported in many different ways. To achieve an effective review of different studies, a consistent presentation of the results is necessary. This paper aims to exemplify the main topics related to summarising and pooling research findings from multivariable models with a quantitative response variable. Methods: we outline the complexities involved in synthesising associations. We describe a method by which it is possible to transform the findings into a common effect size index which is based on standardised regression coefficients. To describe the approach we searched original research articles published before January 2012 for findings of the relationship between polychlorinated biphenyls (PCBs) and birth weight of new-borns. Studies with maternal PCB measurements and birth weight as a continuous variable were included. Results: the evaluation of 24 included articles reveled that there was variation in variable measurement methods, transformations, descriptive statistics and inference methods. Research syntheses were performed summarizing regression coefficients to estimate the effect of PCBs on birth weight. A birth weight decline related to increase in PCB level was found. Conclusions: the proposed method can be useful in quantitatively reviewing published studies when different exposure measurement methods are used or differential control of potential confounding factors is not an issue.

Do moss samples, pollen traps and modern lake sediments all collect pollen in the same way? A comparison from the forest limit area of northernmost Europe

Moss polsters, pollen traps and lake surface sediment samples are commonly used as climate calibration data or as modern analogues for reconstructing vegetation from fossil profiles, but the differences in pollen content between these media have received little attention. This study aims to analyse how the three media differ in reflecting individual vegetation types and spatial differences in vegetation. 119 modern samples (64 moss polsters, 37 lake surface sediment samples and 18 pollen traps from which a collection was made annually) were taken from northern Fennoscandia and the Kola Peninsula as a broad transect crossing the northernmost forest limits of Betula pubescens ssp. czerepanovii (mountain birch),Pinus sylvestris (Scots pine) and Picea abies (Norway spruce). The pollen assemblages from these samples were compared with the surrounding vegetation visually and via PCA (principle components analysis) and cluster analysis. Both comparisons allow a correct distinction between pollen assemblages of arctic/alpine heath, mountain birch dominated areas, and boreal coniferous forests. The differences between the vegetation zones are stronger than the differences between the sampling media. Nevertheless, lake sediment samples from the mountain birch woodland zone tend to overestimate pine and underestimate birch. Pollen traps are biased towards lower tree pollen percentages and higher values of shrubs, herbs and Cyperaceae. This bias is especially strong in traps that have missing years in the data. Irrespective of the vegetation zone, pollen traps tend to have lower Pinus pollen percentages than in the adjacent moss polsters.

Polychlorinated biphenyls (PCBs) in relation to secondary sex ratio – A systematic review of published studies

There is reasonably strong evidence linking reduced secondary sex ratio (proportion of males) and environmental exposures. Polychlorinated biphenyls (PCBs) are persistent contaminants of the environment and several studies have reported an association of PCBs with birth outcomes. A decrease in the male/female sex ratio at birth has been reported in some, but not all studies. The aim of this systematic review was to summarize and pool the research findings about the influence of PCBs on sex ratio. Several article databases and reference lists of identified articles were searched. Studies reporting the proportion of boys and girls born to individuals who were exposed to high PCB concentrations were included. The primary outcome measure was the proportion of males in groups exposed to high or low levels of PCBs. Studies with both direct and indirect surrogate PCB measurements were included. The search and selection resulted in 15 eligible studies on the association between the sex ratio and parental PCB exposures. Analyses of the high exposure groups showed that the sex ratio was not significantly altered from the historical reference range in 13 of the 15 articles. The majority of the exposure studies reported also internal comparisons between high and low PCB exposure levels. The pooled 95% confidence interval estimate for the difference in high and low maternal exposure with direct PCB measure was - 0.048 with 95% CI of (-0.121, 0.026). There was no strong or moderate indication that parental exposure to PCBs alters the sex ratio of the children.

Estimation of health risk by using toxicokinetic modelling: A case study of polychlorinated biphenyl PCB153

To assess potential PCB153-associated human health effects and risks, it is necessary to model past exposure. PCB153 blood concentrations, obtained from the AMAP biomonitoring programme, in Inuit women covering the years 1994-2006 at Disko Bay, 1999-2005 at Nuuk, and 1992-2007 at Nunavik were used to extrapolate body burden and exposure to the whole lifespan of the population by the one-compartment toxicokinetic model. By using risk characterisation modelling, calculated Hazard Quotients were higher than 1 between the years 1955 and 1987 for the 90th population percentile and during 1956-1984 for the 50th population percentile. Cancer risk for overall exposure of PCB153 ranged from 4.6×10(-5) to 1.8×10(-6) for the 90th percentile and 3.6×10(-5) to 1.4×10(-10) for the 50th percentile between 1930 and 2049, when central estimates or upper-bound slope factors were applied. Cancer risk was below 1×10(-6) for the same time period when a lower slope factor was applied. Significant future research requirements to improve health risk characterisation include, among others, larger sample sizes, better analytical accuracy, fewer assumptions in exposure assessment, and consequently, a better choice of the toxicity benchmark used to develop the hazard quotient.

Role of Winter Weather Conditions and Slipperiness on Tourists’ Accidents in Finland

(1) Background: In Finland, slippery snowy or icy ground surface conditions can be quite hazardous to human health during wintertime. We focused on the impacts of the variability in weather conditions on tourists’ health via documented accidents during the winter season in the Sotkamo area. We attempted to estimate the slipping hazard in a specific context of space and time focusing on the weather and other possible parameters, responsible for fluctuations in the numbers of injuries/accidents; (2) Methods: We used statistical distributions with graphical illustrations to examine the distribution of visits to Kainuu Hospital by non-local patients and their characteristics/causes; graphs to illustrate the distribution of the different characteristics of weather conditions; questionnaires and interviews conducted among health care and safety personnel in Sotkamo and Kuusamo; (3) Results: There was a clear seasonal distribution in the numbers and types of extremity injuries of non-local patients. While the risk of slipping is emphasized, other factors leading to injuries are evaluated; and (4) Conclusions: The study highlighted the clear role of wintery weather conditions as a cause of extremity injuries even though other aspects must also be considered. Future scenarios, challenges and adaptive strategies are also discussed from the viewpoint of climate change.

Quantitative estimation of mercury intake by toxicokinetic modelling based on total mercury levels in humans

Mercury is a toxic metal that can be disseminated into the environment from both natural and anthropogenic sources. Human exposure to the metal stems mainly from food, and more particularly from the consumption of fish and other seafoods. Examining dietary exposure and measuring mercury levels in body tissues are two ways of estimating exposure to mercury. In this study, we utilized a modelling system consisting of three linear toxicokinetic models for describing the fate of methyl mercury, inorganic mercury, and metallic mercury in the body, in order to estimate daily intake of mercury as measured through total mercury concentrations in the blood. We then compared the results stemming from our modelling system to those of the detailed semi-quantitative food frequency questionnaire (FFQ) of the Norwegian Fish and Game (NFG) Study, a project that focused on dietary mercury exposure. The results indicate that toxicokinetic modelling based on blood levels gave higher daily intake values of mercury compared to those of the FFQ. Furthermore, the former had a wider range of estimates than the latter. The properties of the toxicokinetic model or limitations in the dietary exposure assessment could be posited as reasons for the differences between the respective methods. Moreover, the results may have been influenced by sources of mercury exposure that cannot be described as dietary, such as amalgam fillings.