Cyclic Volatile Methylsiloxane Bioaccumulation in Flounder and Ragworm in the Humber Estuary

Abstract

Cyclic volatile methylsiloxanes are being subjected to regulatory scrutiny as possible PBT chemicals. The investigation of bioaccumulation has yielded apparently contradictory results, with high laboratory fish bioconcentration factors on the one hand and low field trophic magnification factors on the other. In this study, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were studied along with polychlorinated biphenyls (PCBs) in sediments, ragworm, and flounder from six sites in the Humber Estuary. Bioaccumulation was evaluated using multimedia bioaccumulation factors (mmBAFs) which quantified the fraction of the contaminant present in the aquatic environment that is transferred to the biota. PCB 180, a known strongly bioaccumulative chemical, was used as a benchmark. The mean mmBAF of D5 was about twice that of PCB 180 in both polycheates and flounder, while for D4 it was 6 and 14 times higher, respectively. The mmBAF of D6 was a factor 5-10 lower than that of PCB180. The comparatively strong multimedia bioaccumulation of D4 and D5, even in the absence of biomagnification, was explained by both compounds having a >100 times stronger tendency to partition into lipid rather than into organic carbon, while PCB 180 partitions to a similar extent into both matrices.

Methyl Siloxanes in Environmental Matrices around a Siloxane Production Facility, and Their Distribution and Elimination in Plasma of Exposed Population

“…Because of their wide use, these methyl siloxanes are present in many environmental matrices. 4−7 Furthermore, some methyl siloxanes bioaccumulate in some biota, such as fish and ragworm, 8 due to their high octanol−water partition coefficients. Recently, the toxicity of methyl siloxanes to the reproductive, immune, and nervous systems of animals and humans has become a public health concern.…”

Problemas en el análisis de metilsiloxanos volátiles (VMS): origen y soluciones

“…Así mismo, se ha utilizado grasa de cerdo homogeneizada como blanco de muestreo para la determinación de D4, D5 y D6 en hígado de peces y grasa de focas, 39,48 y el adsorbente Isolute ENVI+ (~60 mg) se ha empleado como blanco de muestreo en el análisis de D4, D5 y D6 en zooplancton y peces. 2,41 Debe decirse que todas estas alternativas pueden ser aceptables para la preparación de muestras blancas para el análisis de VMS, siempre y cuando las mismas permitan simular de manera suficientemente adecuada el comportamiento de las muestras reales durante el muestreo y el análisis.…”

“…Dentro de esta familia de compuestos los metilsiloxanos de cadena corta conocidos como metilsiloxanos volátiles (VMS), han recibido una especial atención en los últimos años debido a su elevada capacidad de bioacumulación, [1][2][3][4][5][6][7] potencial cancerogenicidad [8][9][10] y amplia distribución ambiental. [11][12][13][14][15][16][17][18][19][20][21] Estos compuestos se presentan en conformaciones lineales o cíclicas tal y como se ilustra en la Figura 1, y se caracterizan principalmente por presentar una elevada presión de vapor (2.3 -5620 Pa a 25 o C) y baja solubilidad en agua (0.07 -1560 µg L -1 a 25 o C).…”

The potential of methylsiloxanes as solvents for synthetic chemistry applications

“…[50][51][52] However, further studies are clearly needed on the bioaccumulative effects of VMSs as not all studies are in agreement (see for example, ref. 40). This current study does not attempt to review in detail the environmental aspects of siloxanes, however, they do need to be borne in mind.…”