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Subject: Re: [DCHAS-L] LD50 Source Data

Date: Oct 18, 2019 15:52 UTC

Author: Margaret Rakas <mrakas**At_Symbol_Here**SMITH.EDU>

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Subject: Re: [DCHAS-L] LD50 Source Data

Date: Oct 18, 2019 16:39 UTC

Author: Jim Stewart <jhstew36**At_Symbol_Here**GMAIL.COM>

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From: Monique Wilhelm <mwilhelm**At_Symbol_Here**UMICH.EDU>

Subject: Re: [DCHAS-L] Validity of the risk matrix

Date: Oct 18, 2019 15:58 UTC

Reply-To: ACS Division of Chemical Health and Safety

In-Reply-To: Re: [DCHAS-L] Validity of the risk matrix

Demystify: 

I am sticking WITH the use of the matrix for lab safety. I will admit, when it was first taught to me in my undergrad (back in the days of Hugh B Safe) I did not understand risk assessment and thought the whole process was useless. At that time we were asked to add values of 1-100 for the risk. I was probably hung up on assigning that number and hoping to get it "right".

Now, I teach risk assessment using a matrix and values of low, medium, high. I also explain that they will vary from person to person based on their experiences and have them apply it to a before PPE and other controls scenario and after controls to show that the goal is to use the controls to take the risk level down even though they can do nothing about the hazard itself. To me, I do expect to see some variation in what one would call a medium hazard another may call high. But, the point is that these end up benign RELATIVE hazard and risk values and will change with level of experience. (ie Gen Chem is afraid of everything they use and even caLL 0.1m HCl high risk because it has a hazard, but when they get to orgo it falls to be much lower).

Monique

_________________________________________________________

Monique Wilhelm, M.S., NRCC Certified CHO

ACS CHAS Secretary|2017 CERM E. Ann Nalley Award Recipient

Laboratory Manager|Adjunct Lecturer|Chemistry Club Advisor

Department of Chemistry & Biochemistry|University of Michigan-Flint




On Fri, Oct 18, 2019 at 10:08 AM Wright, Mike <mwright**At_Symbol_Here**usw.org> wrote:

This has been a very good discussion. I'm a bit fanatical on this because I=E2=80™ve seen too many accidents where the facility performed a quantitative safety analysis, manipulated the result, assigned it a low priority, and did nothing. Let me add one more comment and then I'll shut up..

There's another reason why we don't try to plug numbers into a risk matrix (although I guess you could say that we're in effect using 1, 2 and 3). The greater the precision of a number, the more it's open to manipulation. It's easier to understand and challenge a 2 vs. a 3, than a 2.85 vs. a 2.87. And people make decisions all the time on numbers with 3 significant digits when the underlying data is precise to less than 1 significant digit.

As an example of manipulated numbers, here's a link to article on the January Brumadinho tailings dam collapse in Brazil that killed at least 272 people.

https://www.ecchr.eu/en/case/the-safety-business-tuev-sueds-role-in-the-brumadinho-dam-failure-in-brazil/

When the firm charged with certifying the dam's safety got numbers the company didn't like, they just changed the method and got different numbers. Whereas, in the qualitative risk matrix the consequence ranking would have been high, and the probability ranking would have been at least medium, given the known instability of the design and the fact that a similar dam - operated by the same company, no less - had failed a couple of years earlier.

Of course it=E2=80™s also easy to cheat on qualitative assessments. But I'd maintain that it's harder to get away with it.

Mike Wright

Michael J. Wright

Director of Health, Safety and Environment

United Steelworkers

412-562-2580 office

412-370-0105 cell

"My friends, love is better than anger. Hope is better than fear. Optimism is better than despair. So let us be loving, hopeful and optimistic. And we=E2=80™ll change the world."

Jack Layton