Complex sentence: In 1991 they agreed to begin the project by focusing on HPV chemicals, where production volume was used as a surrogate for data on occupational, consumer and environmental exposure (OECD Council Acts, 1991).
Split into simpler sentences: In 1991 they agreed to begin the project by focusing on high production volume (HPV) chemicals. Production volume was used as a surrogate for data on occupational, consumer and environmental exposure (OECD Council Acts, 1991).