HAEMATIN: The effects of this compound are unknown. Handle with care.
EYES - Code 2; SKIN - Code 12; INHALED - Code 14; INGESTED - Code 20

HAEMATOXYLIN: is a natural dye and flammable as a powder and should not be handled close to heat or naked flame. It is a mild irritant to eyes, skin and mucous membranes. Its toxicity has not been quantified. Handle with care.
EYES - Code 2; SKIN - Code 11; INHALED - Code 14; INGESTED - Code 19

HISTOCLEAR: is moderately toxic and a skin, eye and mucous membrane irritant. Dermatitis with sensitisation can develop after prolonged exposure. Inhalation can cause headache and mild disorientation. Haematuria and albuminuria have been reported.
EYES - Code 2; SKIN - Code 12; INHALED - Code 14; INGESTED - Code 21

HISTOLENE: is moderately toxic and a skin, eye and mucous membrane irritant. Dermatitis with sensitisation can develop after prolonged exposure. Inhalation can cause headache and mild disorientation. Haematuria and albuminuria have been reported.
EYES - Code 2; SKIN - Code 12; INHALED - Code 14; INGESTED - Code 21

HYALURONIDASE: is an enzyme which digests certain acid mucins. It will cause irritation to the eyes and skin.
EYES - Code 3; SKIN - Code 9; INHALED - Code 14; INGESTED - Code 22

HYDROGEN PEROXIDE: is a strong oxidising agent and is very corrosive. It is a severe eye and mucous membrane irritant. Exposure of the eyes to the vapour causes irritation whilst a liquid splash causes severe burning with loss of sight. A liquid splash to the skin will burn and bleach but there should not be permanent damage. Inhalation of the vapour will irritate the mucous membranes with coughing and shortness of breath. Ingestion of the liquid will cause localised burning and severe irritation.
EYES - Code 3; SKIN - Code 5; INHALED - Code 15; INGESTED - Code 19

HYDROCHLORIC ACID: is a strong irritant and corrosive and must be handled with great care. It will cause severe burns to exposed skin and eyes. The vapour is also a strong irritant and corrosive. Always use a fume hood when handling this acid. Always add acid to water and never water to acid as the heat generated may cause a violent reaction.
EYES - Code 3; SKIN - Code 9; INHALED - Code 14; INGESTED - Code 22

HYDROQUINONE: is a toxic substance which may cause dizziness, nausea, vomiting, headache, cyanosis, delirium and ultimately collapse. Skin contact may cause dermatitis. It is an eye irritant.
EYES - Code 2; SKIN - Code 11; INHALED - Code 14; INGESTED - Code 20

HYPOCHLORITES: are oxidising agents, corrosives and strong eye irritant which can cause permanent eye damage. In concentrated form hypochlorites can cause skin irritation and burns and will damage mucous membranes. Ingestion leads to abdominal pain, nausea and vomiting.
EYES - Code 3; SKIN - Code 12; INHALED - Code 16; INGESTED - Code 23