Lynas’ waste as harmless as table salt? Really?

ARCHIVES 2012

By admin-s On May 9, 2012

Lee Wee Tak

A very well researched and written article by Mr Soo Jin Hou which was denied publication elsewhere….for what reason, I do not know.

In a highly publicized press conference on 3 April 2012, Lynas demonstrated that their WLP waste is lower in radioactivity than table salt [1] [2]. The implication of this experiment is very detrimental to the stop Lynas campaign. One of the main rebuttal against the IAEA review is that its International Commission on Radiological Protection (ICRP) model has underestimated the risk of internal emitters, which are radioactive particles that are ingested or inhaled. If the common salt has higher radioactivity than Lynas’ wastes, the entire argument on internal emitters will be void.

Fortunately, Mr. Tan Sek Choong, feature writer from Merdekareview.com found out that Lynas has been misleading the public in their experiment [3]. He found out that the salt used is not the typical sodium chloride (NaCl) type used in Malaysian households, but a low-sodium substitute containing potassium chloride (KCl). The brand of the substitute is Diet Rite Lite Salt and it is imported from Australia (see picture). High sodium intake can lead to hypertension, and the substitute is thought to be a healthier alternative, although KCl is toxic when consumed in excess [4].

The radioactive isotope potassium-40 (K-40) constitutes 0.012% of all potassium. It is the source of elevated radioactivity of the experimental salt. By the omission of its real content, Lynas sought to create the false impression that typical Malaysians are already exposed to this source of radiation.

The table below compares the radioactivity of household salt, Diet Rite Lite Salt as well as the WLP waste:

	Household Salt (NaCl)	Diet Rite Lite Salt (NaCl+KCl)	WLP Waste
Radioactive composition	Negligible	27.6% K [5] x 0.012% = 0.00331% K-40	0.1455% Th-232 (in 0.1655% ThO2), 0.0019% U-238 (in 0.00225% U3O8)
Decay rate per gram	Negligible	7.1×10-6 Ci/g [6] x 3.7×1010 Bq/Ci x 3.31×10-5 = 8.7 Bq/g	6.1 Bq/g
Radiation dosage measured during press conference		1.1 µSv/hour	0.7 µSv/hour

In theory, Diet Rite Lite Salt has higher decay rate than the WLP waste. The radiation dosage taken during the press conference also shows higher reading. Since the former is edible, does it mean that the WLP waste is safe?

K-40 is generally regarded as relatively safe within the medical community, despite its radioactivity [7]. The reasons are:

a) K-40 is distributed mostly in cancer resistant muscle tissue, whereas thorium (Th-232) is deposited mostly in leukemia prone bone tissue,

b) K-40 is easily excreted and it has a biological half-life of 30 days, compared to 22 years for Th-232 lodged in the bone,

c) Alpha radiation from Th-232 is 20 times more damaging than beta and gamma radiation from K-40.

d) The lifetime cancer mortality risk for the inhalation of Th-232 is 200 times greater than inhalation of K-40, and nearly 2000 times greater than ingestion of K-40 [6].

As a result, dosage for dosage, the Diet Rite Lite Salt poses much smaller threat compared to the WLP waste.