Nickel and Cobalt Accumulation and Human Health Risk in Guava (Psidium guajava L.) Under Wastewater Irrigation: A Soil–Plant Transfer Assessment - Zafar Iqbal Khan; Kafeel Ahmad; Asma Ashfaq; Sana Anwar; Shahzad Akhtar; Ijaz Rasool Noorka; Muhammad Irfan Ashraf; Ilker Ugulu (Bulletin of Environmental Contamination and Toxicology, 2026)