Monika Filipsson

Metal uptake by homegrown vegetables : the relative importance in human health risk assessments at contaminated sites

Risk assessments of contaminated land often involve the use of generic bioconcentration factors (BCFs), which express contaminant concentrations in edible plant parts as a function of the concentration in soil, in order to assess the risks associated with consumption of homegrown vegetables. This study aimed to quantify variability in BCFs and evaluate the implications of this variability for human exposure assessments, focusing on cadmium (Cd) and lead (Pb) in lettuce and potatoes sampled around 22 contaminated glassworks sites. In addition, risks associated with measured Cd and Pb concentrations in soil and vegetable samples were characterized and a probabilistic exposure assessment was conducted to estimate the likelihood of local residents exceeding tolerable daily intakes. The results show that concentrations in vegetables were only moderately elevated despite high concentrations in soil, and most samples complied with applicable foodstuff legislation. Still, the daily intake of Cd (but not Pb) was assessed to exceed toxicological thresholds for about a fifth of the study population. Bioconcentration factors were found to vary more than indicated by previous studies, but decreasing BCFs with increasing metal concentrations in the soil can explain why the calculated exposure is only moderately affected by the choice of BCF value when generic soil guideline values are exceeded and the risk may be unacceptable.

A risk assessment perspective of current practice in characterizing uncertainties in QSAR regression predictions

The European REACH legislation accepts the use of non‐testing methods, such as QSARs, to inform chemical risk assessment. In this paper, we aim to initiate a discussion on the characterization of predictive uncertainty from QSAR regressions. For the purpose of decision making, we discuss applications from the perspective of applying QSARs to support probabilistic risk assessment. Predictive uncertainty is characterized by a wide variety of methods, ranging from pure expert judgement based on variability in experimental data, through data‐driven statistical inference, to the use of probabilistic QSAR models. Model uncertainty is dealt with by assessing confidence in predictions and by building consensus models. The characterization of predictive uncertainty would benefit from a probabilistic formulation of QSAR models (e.g. generalized linear models, conditional density estimators or Bayesian models). This would allow predictive uncertainty to be quantified as probability distributions, such as Bayesian predictive posteriors, and likelihood‐based methods to address model uncertainty. QSAR regression models with point estimates as output may be turned into a probabilistic framework without any loss of validity from a chemical point of view. A QSAR model for use in probabilistic risk assessment needs to be validated for its ability to make reliable predictions and to quantify associated uncertainty.

Variability and uncertainty in Swedish exposure factors for use in quantitative exposure assessments.

Information of exposure factors used in quantitative risk assessments has previously been compiled and reported for U.S. and European populations. However, due to the advancement of science and knowledge, these reports are in continuous need of updating with new data. Equally important is the change over time of many exposure factors related to both physiological characteristics and human behavior. Body weight, skin surface, time use, and dietary habits are some of the most obvious examples covered here. A wealth of data is available from literature not primarily gathered for the purpose of risk assessment. Here we review a number of key exposure factors and compare these factors between northern Europe--here represented by Sweden--and the United States. Many previous compilations of exposure factor data focus on interindividual variability and variability between sexes and age groups, while uncertainty is mainly dealt with in a qualitative way. In this article variability is assessed along with uncertainty. As estimates of central tendency and interindividual variability, mean, standard deviation, skewness, kurtosis, and multiple percentiles were calculated, while uncertainty was characterized using 95% confidence intervals for these parameters. The presented statistics are appropriate for use in deterministic analyses using point estimates for each input parameter as well as in probabilistic assessments.

Climate change - an uncertainty factor in risk analysis of contaminated land

Metals frequently occur at contaminated sites, where their potential toxicity and persistence require risk assessments that consider possible long-term changes. Changes in climate are likely to affect the speciation, mobility, and risks associated with metals. This paper provides an example of how the climate effect can be inserted in a commonly used exposure model, and how the exposure then changes compared to present conditions. The comparison was made for cadmium (Cd) exposure to 4-year-old children at a highly contaminated iron and steel works site in southeastern Sweden. Both deterministic and probabilistic approaches (through probability bounds analysis, PBA) were used in the exposure assessment. Potential climate-sensitive variables were determined by a literature review. Although only six of the total 39 model variables were assumed to be sensitive to a change in climate (groundwater infiltration, hydraulic conductivity, soil moisture, soil:water distribution, and two bioconcentration factors), the total exposure was clearly affected. For example, by altering the climate-sensitive variables in the order of 15% to 20%, the deterministic estimate of exposure increased by 27%. Similarly, the PBA estimate of the reasonable maximum exposure (RME, defined as the upper bound of the 95th percentile) increased by almost 20%. This means that sites where the exposure in present conditions is determined to be slightly below guideline values may in the future exceed these guidelines, and risk management decisions could thus be affected. The PBA, however, showed that there is also a possibility of lower exposure levels, which means that the changes assumed for the climate-sensitive variables increase the total uncertainty in the probabilistic calculations. This highlights the importance of considering climate as a factor in the characterization of input data to exposure assessments at contaminated sites. The variable with the strongest influence on the result was the soil:water distribution coefficient (Kd).

Exposure to contaminated sediments during recreational activities at a public bathing place

More and more time is spent on recreational activities, but few risk assessments focus specifically on these situations and exposure factor data are often scarce. To assess exposure to contaminants at a public bathing place in an urban environment, we have compiled literature data, conducted observation studies, and analyzed water and sediment samples. The levels of anthropogenic contaminants are high in urban environments and traffic frequently plays an important role. In this study, to characterize variability and uncertainty, the deterministic exposure calculations for metal pollutants were supplemented by a probability bounds analysis for the polycyclic aromatic hydrocarbons (PAH). The results from these calculations show that oral intake is the major exposure route for metals, while skin absorption, with present assumptions, is more important for the PAH. The presently measured levels of contaminants, at this public bathing place, cannot be anticipated to cause any significant adverse influence on public health. This assessment methodology is easy to adapt and can be used routinely in other situations with more heavily contaminated surface sediments and lake water.

Gender differences in risk management of contaminated land at a Swedish authority

Any risk analysis process leading to the remediation of contaminated land will be affected by individual judgements. Many contaminated land risk assessments in Sweden are reviewed by the County Administrative Board (CAB), a regional government authority. The cost for risk assessments and eventually remediation is funded by whichever operator is legally responsible; however, when the responsible party is unknown, the cost can be met by government grants. A questionnaire was sent to all employees working with contaminated land at each of Sweden’s CABs to investigate whether gender, age and work experience, as well as funding source, affect the reviewing of risk assessments, and the employees’ perception of knowledge gained from the Sustainable Remediation (Hållbar Sanering) research programme. It was found that gender was the most significant factor, but also age and experience of the employees influenced the respondent’s answers. The reviews of risk assessments also varied depending on funding source.

Challenges in assessing the health risks of consuming vegetables in metal-contaminated environments

A great deal of research has been devoted to the characterization of metal exposure due to the consumption of vegetables from urban or industrialized areas. It may seem comforting that concentrations in crops, as well as estimated exposure levels, are often found to be below permissible limits. However, we show that even a moderate increase in metal accumulation in crops may result in a significant increase in exposure. We also highlight the importance of assessing exposure levels in relation to a regional baseline. We have analyzed metal (Pb, Cd, As) concentrations in nearly 700 samples from 23 different vegetables, fruits, berries and mushrooms, collected near 21 highly contaminated industrial sites and from reference sites. Metal concentrations generally complied with permissible levels in commercial food and only Pb showed overall higher concentrations around the contaminated sites. Nevertheless, probabilistic exposure assessments revealed that the exposure to all three metals was significantly higher in the population residing around the contaminated sites, for both low-, median- and high consumers. The exposure was about twice as high for Pb and Cd, and four to six times as high for As. Since vegetable consumption alone did not result in exposure above tolerable intakes, it would have been easy to conclude that there is no risk associated with consuming vegetables grown near the contaminated sites. However, when the increase in exposure is quantified, its potential significance is harder to dismiss - especially when considering that exposure via other routes may be elevated in a similar way.

Risk perception and worry in environmental decision-making – a case study within the Swedish steel industry

Sustainable development is an important issue for the industry in order to fulfil legislation requirements and to be able to use green marketing as a competitive advantage. The Swedish steel industry has implemented a large number of environmental improvements, for example, within energy efficiency, raw materials and recyclability. Technical improvements can help the industry decrease its environmental impact; however, in order to reach sustainable development, more factors need to be considered: an effective environmental decision-making process, for example. This process may be influenced by personal factors such as risk perception and worry, which are factors that will not contribute to an effective decision-making process. The aim of this study was to investigate if personal worry and risk perception influenced environmental decision-making within the Swedish steel industry. Thirty-eight interviews were performed at 10 Swedish steelworks using the Q-methodology. The major perceived environmental risks with the facility and personal worry were assessed, compared to the day-to-day work. It was concluded that the major perceived risks were emissions of carbon dioxide, use of non-renewable energy and emissions of particulate matter. The decision-makers were mainly worried about emissions of carbon dioxide, emissions of dioxin and use of non-renewable energy. The environmental issues that were prioritised in practice (day-to-day work) were emissions of carbon dioxide, emissions of particulate matter and emissions of metals. Even though emissions of carbon dioxide were given the highest priority in the Q-sorts, there was in general no clear relationship between risk perception and personal worry with the prioritised environmental issues at the steelworks. The quantitative analysis of the Q-sorts and the qualitative interviews both showed that the day-to-day work was unaffected by personal worry and risk.