The DIOXIN2018 conference was held in Krakow, Poland, 26-31 August, 2018 with about 1000 participants from all over the World. The event included the 38th International Symposium on Halogenated Persistent Organic Pollutants and the 10th International PCB Workshop.
A few brief notes
There was a plenary every day and six parallel oral sessions. In addition, hundreds of poster presentations were exposed during the event.
All the plenary speeches were very good; however, I was especially happy with the update on legacy and emerging perfluoralkyl substances (PFAS) made by two of the pioneers in the area: Kannan from USA and Yamashita from Japan. They explained toxicity the historical development of the science before and after the first PFAS paper by Giesy and Kannan published in 2001, showing the occurrence of PFOS a. o. in polar bears. The research was paid by 3M Company and resulted in a phase-out of that chemical by 3M.
Another very exciting plenary was “The effect of fire retardants on smoke toxicity” by Richard Hull from UK. He showed that plastics with added flame/fire retardants in a fire will form more of the toxic gasses emitted from a fire and kill more people.
Standing lunch in Krakow with among others Richard Hull (right)
Some PFAS presentations:
Swedish scientists detected known and unknown fluorinated compounds in 31 cosmetic products (cream, foundation, pencil, powder and shaving cream) and made fluorine mass balance calculations and human exposure scenarios. In the ingredient lists of 24 products fluorinated compounds were listed. s. Identification and quantification of 47 targeted PFAS was carried out by UPLC-MS/MS. In addition extractable organic fluorine (EOF) and total fluorine (TF) were determined. The highest PFAS concentrations in powder and foundation were respectively 679 and 480 µg/g. PFHxA and PFHpA as well as monoPAPs (6:2 and 8:2) and diPAPs (6:2/6:2, 6:2/8:2 and 8:2/8:2) were amongst the major PFASs detected in the samples. Whereas PAPs are added intentionally as active ingredients to some the products, PFAAs are more likely to be impurities and/or degradation products from other telomer-based PFASs, as they are not listed as ingredients in any of the samples. Several of the (supposedly) fluorine-free samples contained quantifiable levels of TF (3 products) and EOF (5 products). The estimated serum concentrations of PFOA and PFHpA after five years of exposure to foundations and powders were 2.20 and 1.36 ng/mL for the high exposure scenario and 0.0011 and 0.0013 ng/mL for the intermediate scenario.
In a municipal wastewater treatment plant (WWTP) in China, PFASs were not degraded. The annual average concentrations of PFASs in influents were 46.4 ng/L; while in effluents are 38.5 ng/L. Perfluorobutanoic acid (PFBA) were the predominant compound of PFASs in wastewater, while perfluorooctanesulfonic acid (PFOS) were the major PFAS in sludge.
PFAS was also studied by a Swedish research group in some WWTP in Nordic countries. The sum of up to 63 identified PFAS and a fraction of unidentified extractable organic fluorine were measured. The fraction of unidentified was more than 40%. The total concentrations of PFASs in effluents were between 34 ng/L and 109 ng/L and between 36 ng/g and 143 ng/g dw in sludge samples. The highest levels of PFAS in effluents were in samples from Sweden and the highest levels in sludge were observed in samples from Denmark.
A Swedish study of the mass flow and fate of 28 per- and polyfluoroalkyl substances in a landfill found PFAS concentrations in leachate of up to 1800 ng/L. That was lower than in many other countries. Overall, PFAS was ubiquitously present in leachate, drainage, sludge, groundwater and receiving water samples at the landfill. In the aqueous phase, the shorter chain PFAS dominated over the longer chain PFAS.
In 2017, some scientists from Hamburg with HPLC-MS/MS measured 36 PFAS in surface waters and sediments along the German coastline. . In general, the sum of PFASs in the Baltic Sea was two to three times lower than in the North Sea (2.5 vs. 5.9 ng/L in average). The spatial distribution of PFAS in sediment samples was more varying than for water samples in terms of concentration levels and distribution pattern.
Some Flame retardant presentations:
German scientists have measured 43 halogenated flame retardants in biota samples from the German North Sea and Baltic Sea coast with GC-MS analysis. Samples were eelpout fillet and liver, blue mussels and eggs from herring gulls taken in 2015. In most samples the 7 main PBDE and BDE-209 dominated, and ΣPBDE levels in herring gull eggs were highest and up to 250 ng/g lw in a North See sample. In eelpout fillet from the Baltic and mussels in the North Sea the max values were 4 ng/g lw and 52 ng/g lw, respectively. In the last 30 years the PBDE levels in mussels have decreased about ten times.
In samples of surface sediments from the River Thames in UK BDE-209 was determined in all 45 samples and accounted for 95% of all PBDEs. The maximum and average concentrations of BDE-209 were respectively 540 and 173 µg/kg dw. The maximum and average concentrations of the sum of the other BDEs were 29 and 5.9 µg/kg dw.
A curious study determined POP chemicals in paprika spices from around the World. The highest concentration found was of 4.5 ng/g PBDE in paprika from China.
In general, there were many new studies of organic phosphorus flame retardants, alternatives to the halogenated.
Some PCB presentations:
Newer animal experiments seems to indicate that PCB-126 is more toxic than previously thought. Therefore, it was suggested in the EFSA session by the Dutch toxicologist Hoogenboom to lower the tolerable weekly intake (TWI) from 14 to 2 pg TEQ/kg bw.
There were several nice Danish presentations related to polychlorinated biphenyls (PCB) in buildings, an issue very much studied in Denmark in recent years.
A large Danish study of PCB measurements in indoor air in 1758 buildings (homes, offices, institutions, etc.) was presented by Majbrith Langeland from SWECO. In addition, there were measured 7.346 samples of building materials from different sources. Paint, capacitors and sealants were the primary sources of PCBs in indoor air. It was found that more than 21% of the buildings from the period 1950 – 1977 had indoor PCB concentrations above 300 ng/m3. The PCB levels in offices, storehouses, workshops, schools and other institutions were an order of magnitude higher than in homes.
On behalf of ten other scientists, Marie Frederiksen from the National Research Centre for the Working Environment in Copenhagen, presented a study of PCB in blood, air, dust, wristbands, hand and surface wipes after PCB exposure in contaminated dwellings in a large housing estate at Brøndby Strand, a suburb to Copenhagen. The indoor PCB levels in the apartments ranged from 300-5000 ng/m3. The wristband was made from silicone, and it was used as a passive, personal sampler of PCB exposure during 7 days.
Efficient Incineration of POPs
A Japanese study showed that until 14% polychlorinated paraffins (SCCP) in wasted consumer products were completely destroyed with an efficiency of 99.99999%, when combusted in a pilot-scale incinerator at 840-900 oC.
In a study from Korea, waste contaminated with hexachlorobutadiene (HCBD) was incinerated in the laboratory at 840 and 1100 oC. At the lower temperature the destruction efficiency was >99.848 % but dioxins were formed. At the high temperature also dioxins were destroyed.