Endocrine Variation : A natural alteration in endocrine activity (either circulating hormone levels or changing response levels) such as that which occurs with ageing, pregnancy or during the menstrual cycle
The Association of Petrochemicals Producers in Europe (APPE), The European petrochemical industry, Glossary of Terms on Chemical Safety for Use in IPCS Publications, van Nieuwenhuyse, Brussels 2006. http://www.petrochemistry.eu/glossary.html, (Petrochem Ind - Brit) {473}