BASF and McGill Team Clash Again Over DINCH Data

Rats exposed to the plasticiser DINCH while in the womb show apparent symptoms of reproductive toxicity, according to a study by a team from McGill University in Montreal, Canada.

But toxicologists at BASF – which introduced DINCH (1,2-cyclohexane dicarboxylic acid diisonyl ester) to the European market in 2002 – describe the study as "flawed" and have criticised the team's data interpretation.

The European Food Safety authority (Efsa) approved DINCH'S use in food contact applications in 2006. The chemical is also found in inks, adhesives, lubricants, toys and medical devices. It is widely seen as a safe alternative to phthalates, which have been identified as endocrine disruptors.

DINCH is often used as an alternative to diethyl hexyl phthalate (DEHP), a substance of very high concern, which is included in the candidate list for authorisation and has some uses restricted under REACH.

McGill lead researcher Vassilios Papadopoulos, now at the University of Southern California, Los Angeles, has long worked on DEHP, examining its effects on reproduction and metabolism. However, he began to focus on DINCH following what he says were reports of DEHP metabolites falling in human blood and DINCH metabolites appearing.

The McGill researchers say they found that exposing male rats to DINCH while in the womb may affect testosterone-producing Leydig cells and cause testes to age prematurely.

Writing in the peer-reviewed Scientific Reports published by Nature, the researchers call for further studies to determine the long-term consequences of DINCH exposure.

Disagreement

However, Rainer Otter and Angelika Langsch from BASF disagree. They say: "The data presented by the authors of this study perfectly confirm at low dose levels what our data, which have been reviewed by competent authorities around the world, indicate at ten times higher dose levels and significantly longer exposure times, that DINCH is a product that does not interfere with testicular function and metabolism."

Observed effects are either physiologic adaptive responses or "toxicologically not meaningful", they add.

Dr Otter and Dr Langsch also refer to a 2015 McGill study, which suggested that a DINCH metabolite called MINCH may have metabolic disrupting properties, stimulating fat cell growth in a similar way to some phthalate metabolites.

At the time, Dr Otter criticised that study's findings in a letter to the journal Environmental Research. Dr Papadopoulos and Enrico Campioli from McGill then published a detailed response and called for more mechanistic studies on DINCH.

Although, Dr Papadopoulos is calling for more research, Drs Otter and Langsch from BASF say there is enough data supporting the subtance's safety.