Sargassum seaweed: limit the exposure of local residents and workers to hydrogen sulphide | handles

Hydrogen Sulfide Toxicity

Individuals are mostly exposed to H₂S by respiratory route. Absorption via the oral and dermal routes is possible, but contributes only slightly to overall exposure.

If the effects in humans related to acute exposure (ie. for a short time) are well known (neurological and respiratory effects of increasing severity with exposure concentration), the effects related to exposure to H₂S over longer durations are less documented. The first effects observed are irritative symptoms of the upper airways and eyes. Neurobehavioral effects and neurological symptoms (headaches, loss of balance and memory) are suspected. Moreover, in the current state of knowledge, given the small number of studies available, no conclusion can be drawn as to the potential carcinogenicity of H₂S. Also note the strong odor nuisance associated with this gas.

In view of the data available, the Agency considers that its prevention recommendations, formulated during a previous expert appraisal concerning workers in contact with decomposing green algae on the coasts of Brittany, should be considered for workers in contact with Sargassum algae.

In addition, the expert report published in 2017 shows that Sargassum seaweed has a strong ability to trap and accumulate heavy metals, in particular arsenic and cadmium, which can pose a risk to human health and the environment.

ANSES’s recommendations

In its opinion “relating to exposure to gaseous fumes from decomposing Sargassum algae in the West Indies and Guyana (PDF)” of March 2017, the Agency indicates:

« L’[agence] emphasizes that current observations and knowledge on emissions/health risks related to the degradation of Sargassum seaweed following stranding are sufficient for the implementation of preventive measures as of now. [Elle] considers that the realization, prior to the implementation of these preventive measures, of an assessment of the health risks linked to the exposure of the inhabitants of the French departments of America to H₂S present in the air and resulting from the decomposition of algae is not relevant.

Thus, considering:

• H concentration measurements₂S already carried out in the ambient air around grounding areas;
• chronic toxicity data for H₂S especially for the upper airways.

it turns out that in the presence of strandings, part of the population is already exposed to concentrations of H₂S higher than the existing chronic TRVs proposed by the US EPA (1.43 ppb – 2 μg.m^-32003) et l’OEHHA (7,14 ppb – 10 μg.m^-32000).

In addition, an increase in the number of medical consultations related to the effects felt by the population of Martinique exposed to H₂S chronically has been reported by the network of sentinel physicians.

These elements therefore justify the immediate implementation of preventive measures in the presence of strandings. »

General recommendations:

• implement the regular and systematic collection of seaweed washed up on the coast ;
• tag the building sites collection of algae, with a Restricted to operators;
• inform the population health risks associated with exposure to H₂S, especially near beaches where seaweed is decomposing. In addition, the population should be informed that seaweed should not be handled.

Recommendations for workers:

During seaweed collection, transport and processing operations, ANSES recommends:

• what each workerincluding in the cabins of mechanical machinery, is fitted with a portable H detector₂Slocated near the respiratory tract;
• that workers wear personal protective equipmentin particular gas-filtering gloves, boots and half-masks, or a power-ventilated hood when the H concentration₂S exceeds 10 ppm;
• to favor a mechanical pickuptaking into account environmental constraints;
• what training and information for workers are provided regularly;
• the implementation of traceability of exhibitor work.

Furthermore, following its expertise published in 2017, the Agency recommends prohibiting the possible use of these algae for human or animal foodpending the completion of more in-depth studies on the contamination of algae by heavy metals.

The Agency also recommends continuing research on:

• exposure related to Sargassum algae stranding situations and the effects on human health;
• the toxicity of H₂S and more particularly on the effects of chronic exposure to low doses of H₂S ;
• the indirect environmental and health impacts linked to the stranding of Sargassum algae (composition of the algae, presence of heavy metals);
• the proliferation and phenomenon of seaweed stranding in the French departments of America.