Week 11 Lecture: MMH2

Question 1

ACGIH TLV for lifting
- purpose
- items considered
- how to use it
- what are its limitations
- validity and reliability

Answer 1

Identifies safe loads (Threshold limit values, TLVs) in lbs for males and females to lift for different conditions
- considers frequency, duration, height of lift, horizontal distance travelled

How to use it
1. Determine task duration (cumulative)
2. <2 hrs/day
3. > 2 hrs/day
4. Determine lifting frequency
5. Use TLV table corresponding to the duration and frequency of the task

• not for one-handed lifts or asymmetric lifts
• not for 2 person lifts
• must be les than 360 lifts per hour
• not for sitting or kneeling postures
• not for high heat or humidity conditions
• not for unstable objects or with poor handles
• not specifically for lowering
• does not consider anthropometry
• low to moderate validity
• moderate reliability

Question 2

MAC tool
- purpose
- limitations
- validity and reliability

Answer 2

• for lifting, carrying, team lifting
• considers many risk factors: Hand distances, vertical lift zones, twisting and side bending, constrained postures, grips, floor surfaces, environmental factors
• not for complex tasks
• requires training
• strong intra- to inter-rater reliability
• valid for risk identification but not risk assessment

Question 3

NIOSH lifting equation
- purpose
- equation
- limitations
- validity and reliability

Answer 3

• predicts recommended weight limit for 90% male population and 75% of female population
• Combines principles for biomechanical and physiological approaches to determine whether a lift or lower is safe

RWL=(LC)(HM)(VM)(DM)(AM)(FM)(CM)

• load constant (23kg)
• horizontal multiplier
• vertical multiplier
• distance multiplier
• asymmetry multiplier
• frequency multiplier
• coupling multiplier

not applicable to asks that involve
- pushing, pulling carrying, one handed lifts, unbalanced loads, slippery surfaces, hot environments, containers larger than 75cm in length

• high validity except at high and low frequencies
• older version is valid for more male dominated industries (even though it doesn’t take into account coupling
• good reliability

Question 4

What is Bakpak

Answer 4

• assessment tool that give you what % of population can do lift. also calculates disc compressive forces
• based on low back pain data collected by Potvin and some epidemiological data

Question 5

LM-MMH EQUATIONS
- developed why
- based on
- pros
- validity and reliability

Answer 5

• developed to replace liberty mutual tables
• based on a meta-analysis of 12 more publications + liberty mutual tables
• easier to use than tables and allows for a wider range of variables and more specific inputs
• good reliability and validity

Question 6

Composite lifting index
- what is it
- what does the index tell you
- limtiations

Answer 6

• cumulative version of NIOSH lifting equation
• estimate of the physical stress associated with overall lifting in work
• NIOSH recommends that the LI or CLI be equal to or lower than 1.0.

only for 2 handed tasks

Question 7

LIFFT
- what is it
- items
- validity and reliability

Answer 7

Cumulative low back loading limits for mono-tasks, multi-tasks and highly variable jobs using engineering principles

Items: weight of load, greatest horizontal distance, number of repetitions

• moderate to good validity for simple lifts
• good reliability

Question 8

How can we assess pushing and pulling tasks?

Answer 8

Liberty mutual equations and mital tables
- worksafebc push/pull calculators
- OHIO push/pull guides
- 3DSSPP

Question 9

How can we assess carrying tasks?

Answer 9

Liberty mutual and mital table
Worksafebc carry calculator
3DSSPP
LM-MMH
MAC