A bit of a wonky blog I’m afraid, but having seen relatively little on the recently introduced Safe Chemicals Act of 2010 and its relevance to engineered nanomaterials on the web, I thought I would post something short and sweet here.

Just over a week ago, Senator Lautenberg introduced a bill in the US Senate aimed at a long-overdue reform of toxic substances regulation in the United States – the Safe Chemicals Act of 2010.  At the same time, Congressmen Rush and Waxman released a discussion draft in the House – The Toxic Chemicals Safety Act of 2010 – covering much of the same ground.  Both documents aim to update substantially the Toxic Substances Control Act, or TSCA – which has been the mainstay of US chemicals regulation since 1976.

Both the 169-page Safe Chemicals Act of 2010 and the slightly shorter 119 page long Toxic Chemicals Safety Act of 2010 aim to bring US chemicals safety regulation into the 21st century.  Richard Denison at EDF has already posted a comprehensive overview of proposed changes to the regulation that I would recommend reading if you are into this stuff.  But here, I thought I would highlight what the proposed changes mean for the engineered nanomaterials – a class of substances that have been a bit of a thorn in TSCA’s side for the past few years.

The problem with TSCA (the old version) is that it is built on a chemicals world-view – substances are regulated based on their unique “molecular identity” – how they are described as chemicals. This works well for substances that do what they do because of their chemistry.  But it runs into problems where something behaves in a certain way because of its physical form, as well as its chemical makeup.  In other words, where you have stuff that is more harmful that molecular identity would suggest because of how the constituent atoms and molecules are put together, you have a problem.

There are workarounds to this within TSCA – a new substance that is chemically identical to an existing one can be regulated under the “Significant New Use Rule” for instance – but it’s a bit of a bootstrap.  And with the emergence of an increasing number of engineered nanomaterials where functionality – and possibly toxicity – depend on physical form as well as molecular identity, this bootstrap has been stretched to breaking point.

So there’s been considerable interest in how the new-look TSCA will handle this.

Fortunately, things are looking good at this stage.  The Senate bill has language that is in effect a substance “get out of jail free” card for EPA.  Section 4 of the bill proposes amending section 3(2) of the original Toxic Substances Control Act with

“Notwithstanding molecular identity, the Administrator may determine, under section 5(a)(6), that a variant of a chemical substance is a new chemical substance.” (page 6)

In other words, EPA can decide when something with the same molecular identity as an existing substance should be treated as a new substance.

And the determiners of when this is justified? The bill proposes that section 3(13) of the 1976 TSCA act is amended with

“(C) SPECIAL SUBSTANCE CHARACTERISTICS.—The term ‘special substance characteristics’ means, such physical, chemical, or biological characteristics, other than molecular identity, that the Administrator determines, by order or rule, may significantly affect the risks posed by substances exhibiting those characteristics. In determining the existence of special substance characteristics, the Administrator may consider—

(A) size or size distribution;

(B) shape and surface structure;

(C) reactivity; and

(D) any other properties that may significantly affect the risks posed.” (page 13)

In other words, the new bill allows many of the characteristics that potentially lead to engineered nanomaterials presenting novel risks to trigger them being treated as new substances.

The House draft document is a little more explicit.  It recommend amending section 3(2) of the original act with:

“(C) For purposes of this Act, such term may include more than 1 form of a substance with a particular molecular identity as described in sub-paragraph (A) if the Administrator has determined such forms to be different substances, based on variations in the substance characteristics. New forms of existing chemical substances so determined shall be considered new chemical substances.” (page 6)

with the clarification that

“The term ‘substance characteristic’ means, with respect to a particular chemical substance, the physical and chemical characteristics that may vary for such substance, and whose variation may bear on the toxicological properties of the chemical substance, including—

(A) chemical structure and composition

(B) size or size distribution

(C) shape

(D) surface structure

(E) reactivity; and

(F) other characteristics and properties that may bear on toxicological properties” (page 11)

Both the Senate bill and the House discussion document provide EPA with the authority to regulate any substance that presents a new or previously unrecognized risk to human health as a new substance.  This is critical to ensuring the safety of engineered nanomaterials, where risk may depend on more than just the chemistry of the substance.  But it also creates a framework for regulating any new material that presents a potential risk – whether it is a new chemical, a relatively simple nanomaterial, a more complex nanomaterial – possibly one that changes behavior in response to its environment, or a novel material that has yet to be invented.  In other words, these provisions effectively future-proof the new regulation.

Of course there’s a long way to go yet.  The final details of the new legislation have to be hashed out between the Senate and the House before they are finally signed off on.  Then the process of interpreting and enacting the new regs starts – including working out how exactly to determine when something should be considered new for regulatory purposes.

But at least things seem on the right track as far as enabling the safe development and use of engineered nanomaterials goes.

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The two documents can been downloaded here:

The Safe Chemicals Act of 2010 (US Senate)

The Toxic Chemicals Safety Act of 2010 (US House of Representatives)