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Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are persistent organic pollutants (POPs) that are prohibited from being produced and used. However, they remain in the agricultural environment and are transferred to crops. In addition, PFOA is classified as possibly carcinogenic to humans. To fully understand the exposure and risk of PFOA and PFOS for human in crops, a residue survey and estimation of dietary exposure assessment are needed. Therefore, we investigated the residues of PFOA and PFOS in upland soil and cultivated root crops. The average residues of PFOA and PFOS in the soil were –1 and 0.024–0.111 μg kg–1, and 0.067–0.193 μg kg–1 and –1 in the crops, respectively. The average PFOA residues were higher than PFOS in the soil and crops. The estimated daily intakes of PFOA and PFOS in the crops were 0.284 ng kgbw–1 day–1 and 0.023 ng kgbw–1 day–1, and the estimated hazard quotients were 0.355 and 0.013, respectively. In addition, the excess cancer risk of PFOA was calculated to be 1.99 × 10–8. Thus, the non–carcinogenic and carcinogenic risks of PFOA and PFOS were not notable from the surveyed residues in the crops. However, the risks may be higher when the residues in other food crops are considered.

Endosulfan was widely used as an insecticide in the agricultural sector before its environmental persistence was fully understood. Although its fate and transport in the environment have been studied, the effects of historic endosulfan residues in soil and its bioaccumulation in crops are not well understood. This knowledge gap was addressed by investigating the dissipation and bioaccumulation of endosulfan in ginseng as a perennial crop in fresh and aged endosulfan-contaminated fields. In addition, the effect of granular biochar (GBC) treatment on the bioaccumulation factor (BAF) of endosulfan residue in ginseng was assessed. The 50% dissipation time (DT50) of the total endosulfan was over 770 days in both the fresh and aged soils under mulching conditions. This was at least twofold greater than the reported (6– > 200 days) in arable soil. Among the endosulfan congeners, the main contributor to the soil residue was endosulfan sulfate, as observed from 150 days after treatment. The BAF for the 2-year-old ginseng was similar in the fresh (1.682–2.055) and aged (1.372–2.570) soils, whereas the BAF for the 3-year-old ginseng in the aged soil (1.087–1.137) was lower than that in the fresh soil (1.771–2.387). The treatment with 0.3 wt% GBC extended the DT50 of endosulfan in soil; however, this could successfully suppress endosulfan uptake, and reduced the BAFs by 66.5–67.7% in the freshly contaminated soil and 32.3–41.4% in the aged soil. Thus, this adsorbent treatment could be an effective, financially viable, and sustainable option to protect human health by reducing plant uptake of endosulfan from contaminated soils.

Peptide nucleic acids (PNAs), artificially synthesized DNA analogues, hybridize strongly with DNA and are useful for fluorescence melting curve analyses (FMCA) based on the thermal denaturation of the probe-target duplex. In this study, we developed a PNA-based one-step real-time RT-PCR assay for the differential and qualitative detection of the porcine reproductive and respiratory syndrome virus genotypes PRRSV1 and PRRSV2. The specificity of the assay was analyzed in silico using previously reported primers and probes and was subsequently verified using Korean PRRSV panels and clinical samples. Seven clinical samples showing low curves with high Ct values were confirmed as negative by FMCA. The sensitivities of one-step real-time PCR for PRRSV1 and PRRSV2 were 15 and 11 copies, respectively, and the results were in 100% agreement with those of conventional RT-PCR combined with nested PCR using clinical samples. Therefore, the assay is highly specific for the detection of current PRRSV1 and PRRSV2 without non-specific amplification by FMCA.

The dynamic orbit determination of a low Earth orbiter using global positioning system single-frequency measurements has been implemented. Currently two methods are being applied to eliminate or reduce ionospheric path delay in single-frequency measurement. One is a group and phase ionosphere calibration technique using code pseudorange and L1 carrier phase, and the other is application of total electron content values from an ionospheric model using only L1 carrier phase to determine the orbit. A new method based on the latter has been developed, which estimates the scale factors of total electron content values in the location of a low Earth orbiter once per each measurement time. Orbit determination using actual global positioning system measurements of the TOPEX/POSEIDON and the Challenging minisatellite payload was conducted to verify the accuracy of the new method. It is verified that, if the total electron content's scale factor estimation technique were applied, 1-m level position accuracy (1σ) for low Earth orbit below 500-km altitudes could be achieved using precision orbit determination based on the global positioning system double-differencing method.