This study conducted an acute toxicity assessment using Daphnia magna to evaluate the potential for increased toxicity when pharmaceuticals persist in aquatic environments not as single substances but in mixed forms. In single-substance toxicity tests, the antibiotics clarithromycin and sulfamethoxazole showed EC50 values of 22.3 mg L-1 and 61.05 mg L-1, respectively. However, the EC50 for the mixture of the two substances was determined to be 31.1 mg L-1. Based on these findings, applying the Similar Mode of Action (MOA) equation from the QSAR Toolbox, as recommended by OECD non-testing methods, produced an estimated EC50 of 33.7 mg L-1 for the mixture, showing a difference of 8.5% compared to the experimental value. This study confirms that combined exposure to pharmaceuticals can increase toxicity due to synergistic effects, indicating a significant potential risk to aquatic ecosystems. According to the UN-GHS classification criteria, clarithromycin, sulfamethoxazole, and their mixture were all classified as Category 3, indicating potential toxicity to aquatic organisms. These results emphasize the importance of toxicity assessments that consider interactions between multiple contaminants in real environmental settings, contributing to the development of effective toxicity evaluation and management strategies for the protection of aquatic ecosystems.

Abstract
서 론
재료 및 방 법
    1. 시험 및 평가대상 성분 및 특성
    2. 용매 선택 및 시험용액의 조제
    3. 물벼룩 급성독성시험
    4. 단일물질 물벼룩 (D. magna) 급성독성시험
    5. 혼합물질 Similar MOA 계산식
    6. 반수영향농도 (EC50)의 도출
    7. UN-GHS 환경위해성 급성독성 분류 검토
결과 및 고 찰
    1. Clarithromycin+Sulfamethoxazole 혼합독성시험
    2. Similar MOA 계산식 적용
    3. 위해성 UN-GHS 기준에 따른 독성 분류 및 위험성 평가
결 론
적 요
REFERENCES

• 김세현(전남대학교 환경에너지공학과) | Sehyeon Kim (Department of Environment and Energy Engineering, Chonnam National University, Gwangju 61186, Republic of Korea)
• 김지현(전남대학교 환경에너지공학과) | Jihyun Kim (Department of Environment and Energy Engineering, Chonnam National University, Gwangju 61186, Republic of Korea)
• 이권섭(전남대학교 환경에너지공학과) | Kwonseob Lee (Department of Environment and Energy Engineering, Chonnam National University, Gwangju 61186, Republic of Korea)
• 김성준(전남대학교 환경에너지공학과) | Seongjun Kim (Department of Environment and Energy Engineering, Chonnam National University, Gwangju 61186, Republic of Korea) Corresponding author