SEGH Articles

Emerging Contaminants in the environment – is there a risk to health?

12 August 2012
In Europe and North America, there has been a gradual decrease in common environmental contaminants (heavy metals such as lead, cadmium; persistent organic pollutants such as DDT, Dioxin, PAH’s) in the environment. Common environmental contaminants, however, remain a public health concern in developing countries and newly industrialised countries.

 

In Europe and North America, there has been a gradual decrease in common environmental contaminants (heavy metals such as lead, cadmium; persistent organic pollutants such as DDT, Dioxin, PAH’s) in the environment. This improvement is largely due to a concerted effort of stricter regulations with improved monitoring, cleaner industrial processes and increased public awareness. Common environmental contaminants, however, remain a public health concern in developing countries and newly industrialised countries.

As we experience a decline in the levels and point sources of common chemicals, the focus has now been on the chemicals which were previously not considered as contaminants. They are not geogenic or air-born but are mainly synthetic by nature and produced to offer a range of societal benefits. Unlike common contaminants, ‘emerging chemical contaminants’ mostly find their way to the environment via diffuse sources i.e. domestic, commercial, and industrial uses. In addition, the development of more sensitive and new analytical capabilities that allows scientist to identify contaminants which are typically present in ultra-low concentrations (parts per billion to parts per trillion). The low concentrations combined with a lack of toxicological evidence make hazard characterisation technically challenging and thus the regulatory standards, where available, tend to be less rigorous and are advisory rather than prescriptive. In some cases (e.g. flame retardants) there are difficulties in identifying safer alternatives even when new evidence emerges about the health risk from the currently used materials.

Some examples of emerging contaminants include: perfluorocarbons ((e.g. perfluorooctane sulfonate (PFOS)), perfluorooctanoic acid (PFOA)), pesticides residues/metabolites (e.g. metaldehyde), pharmaceuticals and personal care products (e.g. steroids and antibiotics, fragrances, cosmetics), nanomaterials (e.g. buckeyballs or fullerenes; carbon nanotubes). These chemicals or their parent products are being manufactured to improve the quality and safety or to increase the efficiency in industrial processes. By nature, they are intended to last long or be resistant to microbial degradation in the environment. For example, PFCs contains only carbon and fluorine bonded together in strong carbon­-fluorine bonds which made them chemically inert and thermally stable. When these chemicals (e.g. PFOS, antibiotics, steroids) are released to the public sewer system, conventional water treatment processes can do little to render them harmless and go unabated to enter the wider environment and biotic food chain as a pollutant.

Our knowledge to relate the presence of emerging chemicals in the environment with public health significance is still at its infancy. Bioassays with animal models indicate the potential for toxicity to humans if exposed to a very high doses but such high dose exposure is unrealistic when compared to typical environmental concentrations. Uncertainty, however, remains over the potential health impacts from a low level chronic exposure due to their persistence and bioaccumulative nature. Studies with ecological receptors e.g. with fish in streams contaminated by steroids have shown evidence of hormone disruption. There is also concern that elevated exposure to antibiotics in water could lead to disease-resistant strains of bacteria, reducing the effectiveness of the current class of drugs. For the human population, the limited data available suggests that there is a need for more “prospective cohort” type study to characterise the association between environmental exposure to these substances, appropriate biomarkers and measurable health outcomes.

 

Emerging chemicals should be a source of concern to ecological and public health in all parts of the world. In this era of financial constraint and interdependent/connected economies, there is a need for shared research programme and data-sharing to enhance analytical capacity to determine their environmental occurrence, fate and transport.  There is also a need for improved risk assessment tools to characterise the exposure and extrapolation of ecological risk to public health if relevant and appropriate. Regulatory policy should encompass emerging chemicals in their monitoring regime, and encourage safer alternatives, increased awareness and risk reduction programme. Societies like the SEGH can facilitate research consortia or a task force drawing from its international expertise to influence the relevant public policy and apply for research funding. Further information on emerging chemicals can be found in websites of various regulatory and public health organisations such as European Chemicals Agency, US EPA, ATSDR.    

 

Sohel Saikat, Health Protection Agency, UK.

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Spatial variability and geochemistry of rare earth elements in soils from the largest uranium–phosphate deposit of Brazil 2018-02-22

    Abstract

    The Itataia uranium–phosphate deposit is the largest uranium reserve in Brazil. Rare earth elements (REEs) are commonly associated with phosphate deposits; however, there are no studies on the concentrations of REEs in soils of the Itataia deposit region. Thus, the objective of the research was to evaluate the concentration and spatial variability of REEs in topsoils of Itataia phosphate deposit region. In addition, the influence of soil properties on the geochemistry of REEs was investigated. Results showed that relatively high mean concentrations (mg kg−1) of heavy REEs (Gd 6.01; Tb 1.25; Ho 1.15; Er 4.05; Tm 0.64; Yb 4.61; Lu 0.65) were found in surface soils samples. Soil properties showed weak influence on the geochemical behavior of REEs in soils, except for the clay content. On the other hand, parent material characteristics, such as P and U, had strong influence on REEs concentrations. Spatial distribution patterns of REEs in soils are clearly associated with P and U contents. Therefore, geochemical surveys aiming at the delineation of ore-bearing zones in the region can benefit from our data. The results of this work reinforce the perspective for co-mining of P, U and REEs in this important P–U reserve.

  • 2017 Outstanding Reviewers 2018-02-21
  • Seasonal occurrence, source evaluation and ecological risk assessment of polycyclic aromatic hydrocarbons in industrial and agricultural effluents discharged in Wadi El Bey (Tunisia) 2018-02-13

    Abstract

    Polycyclic aromatic hydrocarbons are of great concern due to their persistence, bioaccumulation and toxic properties. The occurrence, source and ecological risk assessment of 26 polycyclic aromatic hydrocarbons in industrial and agricultural effluents affecting the Wadi El Bey watershed were investigated by means of gas chromatographic/mass spectrometric analysis (GC/MS). Total PAHs (∑ 26 PAH) ranged from 1.21 to 91.7 µg/L. The 4- and 5-ring compounds were the principal PAHs detected in most of 5 sites examined. Diagnostic concentration ratios and molecular indices were performed to identify the PAH sources. Results show that PAHs could originate from petrogenic, pyrolytic and mixed sources. According to the ecotoxicological assessment, the potential risk associated with PAHs affecting agricultural and industrial effluents ranged from moderate to high for both aquatic ecosystem and human health. The toxic equivalency factor (TEF) approach indicated that benzo[a]pyrene and benz[a]anthracene were the principal responsible for carcinogenic power of samples.