"The International Agency for Research on Cancer (IARC) has determined that occupational exposure to strong inorganic acid mists containing sulfuric acid is carcinogenic to humans. IARC has not classified pure sulfuric acid for its carcinogenic effects." - cdc.gov.
Plants are not very sensitive to sulfate ions. Sulfuric acid doesn't throw off nute ratios. Sulfuric acid helps the plant "digest" stored nutes. Most commercial growers use sulfuric acid to lower pH. If you choose sulfuric acid or any acid to lower pH wear acid safe gloves, a splash shield, and don't spray (mist) it in the air you breathe (don't use in foliar sprays). And don't use "battery acid" use "sulfuric acid". "Battery acid" is sulfuric acid contaminated with heavy metals. Sulfuric acid is sulfuric acid.